II.CHEMICALSCIENCE.◊1.On the Specific Heat of Gases, byMM. de la RiveandMarcet.—The principle on which these philosophers proceeded in their researches, was, to expose equal volumes of different gases to an equal source of heat during equal times, and to judge, by the augmentation of elastic force in each gas, the temperature which it had acquired. The apparatus was a kind of manometer, and consisted of a glass balloon to retain the gas, and a bent tube attached to it, which, descending into a vessel of mercury, served to show, by the column of metal within it, what was the elasticity of the gas. This method was adopted, because, i. The gas was not altered in volume by the change of temperature, its elasticity only changing: ii. The temperature was indicated by the gas itself, and not by a thermometer: iii. Water was easily separated previously from the gases, and excluded from the apparatus: iv. All the gases were placed in exactly the same circumstances, so as to render it unnecessary to refer to any calculation for the purpose of comparison.Two methods of applying heat were resorted to: in one the balloon, containing the gas at a certain temperature, was placed in water at a higher but constant degree, for a certain time (generally4′),and the elevation of temperature noticed: in the other, the balloon with the gas was inclosed in a larger copper balloon, blackened inside, and the space between the two exhausted as much as possible of air; the apparatus being then immersed in warm water, the heat gained access slowly to the gas, and the time of each experiment was increased, at the same time that certain sources of error were avoided.The gases experimented with were, atmospheric air, oxygen, azote, hydrogen, carbonic acid, olefiant gas, oxide of carbon, nitrous oxide, nitrous gas, sulphuretted hydrogen, ammonia, sulphurous acid, muriatic acid, and cyanogen. Great care was taken in their preparation. The result of the experiment was very unexpected; for, during the five minutes allotted for each, all had acquired the same temperature,—a circumstance which proves that they all have thesame specific heat. The equal volumes of gas at the pressure of 65 centimeters (15.59 inches) and the temperature of20° C.,being exposed to a source of heat at30° C.,acquired a mean temperature of 6.32 degrees in five minutes, the extreme difference, in any of the experiments, not being more than 0.04 of a[p201]degree. One gas only forms an exception to the above statement, namely, hydrogen, which was always heated more than the others, namely, to 6.6 degrees in the five minutes. This effect is considered as due not to any difference in specific heat, but to a difference in conducting power.Experiments were then made with dilated gases, to ascertain whether dilatation caused any change in capacity, and it was found to diminish slowly but regularly with the diminution of pressure. These results, with a third which is also interesting, have been thus generally expressed by the authors at the end of their memoir.i. All gases in equal volumes, and at the same pressure, have the same specific heat.ii. Other circumstances being the same, the specific heat of gases diminishes with diminution of pressure, and equally for all the gases: the progression converges slightly and in a ratio much less than that of the pressures.iii. Each gas has a different conducting power,i.e., all the gases have not the some power of communicating or receiving heat.—Ann. de Chimie, xxxv. 5.2.On the Incandescence and Light of Lime.—The experiments made by Lieutenant Drummond upon the light of lime and other earths when highly ignited, with the highly interesting application which he has made of that emitted from lime, to the purpose of geodesical surveys, has induced M. Pleischel to repeat and vary the results. He states that the utmost light is given by lime; the earth being pulverised and exposed on burning charcoal to the heat excited by a jet of oxygen falling upon it. He endeavours to account for the effect, by supposing a kind of pulverulent atmosphere disengaged from the lime at the high temperature used, and considers that the substances which are competent to emit molecules only in the gaseous state, cannot produce this intense light.—Zeitschrift für Physik, &c.3.Evolution of Heat during the Compression of Water. May 14, 1827.—M. Arago announced to the Academy of Sciences, that M. Despretz had ascertained experimentally, that the compression of water by a force equal to 20 atmospheres, caused the disengagement of one sixty-sixth part of a degree of heat.4.On Electrical Excitation.—M. Walcker affirms positively from experiments made with great care, that three bodies of different exciting power are necessary, in every case of excitation of electricity by contact, and that all the phenomena of this kind are subject to this condition. If, for instance, two portions of the same metal being put in contact, electricity is produced, it is because there are three different states of temperature brought into play, one being the result of the other two, and a mean between them. One fact which more than any other sanctioned this idea, was, that the electric[p202]currents were the more apparent as this third state of temperature was made more sensible.—Bull. Univ., A. vii. 374.5.Magnetic Repulsion.—A very remarkable result has been obtained by M. Becquerel, from the use of an extremely delicate magnetic arrangement, which he has for the present called asideroscope. Its use is exactly the same in principle as that of the magnetic needle, indicating iron, for instance, by the attraction manifested; but it is so delicate that it will show it in the most minute quantity possible, as, for instance, in gold, silver, or copper money, innumerable minerals, &c. This instrument shows no magnetic power or attraction in gold, silver, copper, palladium, tin, lead, zinc, or brass, when chemically pure, and a great many vegetable and mineral substances have no action on it: but the most curious result is, that very pure bismuth and even that of commerce has arepulsivepower, which, if it be found ultimately to be independent of any magneticpolarity, is the first fact of the kind that has been made known. Antimony also presents the same phenomenon.6.Diminished Solubility of Substances by Heat.—Mr. Graham has added one to the few facts of this kind with which we were acquainted, and has accompanied its description with some very interesting considerations, which may be found at length in the Philosophical Magazine, N. S., ii. 20. The salt experimented with by Mr. Graham is the phosphate of magnesia; which may be prepared by mixing a solution of 21 parts of phosphate of soda with one of 15.375 parts of sulphate of magnesia: within 24 hours the phosphate of magnesia precipitates in acicular crystals; they should be agitated with repeated portions of water, then thrown upon a filter with more water, and left to dry.Solutions were obtained by occasionally agitating this salt with water in the proportion of 2 ounces to a pint of the fluid, for four days; being then decanted and filtered, they had a sweetish taste. A quantity of this fluid being heated in a water-bath, became turbid before the temperature had attained120° F.;at212°a cloudy precipitate slowly subsided, and the supernatant fluid became nearly transparent. The precipitate was found to be anhydrous phosphate of magnesia; and, by further experiment, the difference in solubility was found to be such, that water at 45°, dissolving1744thpart its weight of the anhydrous salt, water at 212° only dissolved11151thpart. When in the state of crystals, or as hydrate, the proportions of salt were1322and1498to 1 of water.Mere continuance of the heat had no effect in increasing the precipitate either of this salt, or from aqueous solution of lime, provided no part of the solution was at any time converted into vapour; but if the solution only occupied a small part of the vessel, and ebullition came on, then, although all the water might be returned to the solution, yet the precipitation went on, and might be[p203]increasedad libitum, particularly in the case of lime water. The cause of the precipitate appears to be the same in all these cases. The moment a drop of the solution is converted into vapour, it deposits the quantity of lime or salt which it held in solution; and in the case of bodies which dissolve so sparingly and with so much difficulty, although the water be returned again to the solution, it is incapable of re-dissolving what it has deposited. We know that it would be a hopeless task to form a saturated solution of lime by agitating with the water no more than the few grains which it is capable of dissolving; and in the case of ebullition, when the lime is once deposited, there should be the same difficulty in taking it up.Mr. Graham states that he has observed this effect not only in lime-water and in solution of phosphate of magnesia, but to a certain extent in all bodies of difficult solubility, in the sulphate of lime, for instance, even when greatly diluted; and he believes that the deposite from slight boiling observed in many mineral waters, and generally attributed to the dissipation of carbonic acid gas, depends, in some instances, upon this cause. However weak the solution may be, it is evident that a portion of the salt may be deposited in this way.7.On the Composition of Cyanic Acid.—M. Wohler some time since announced the production of cyanic acid, and cyanates, corresponding in composition to the substance presumed to exist in the fulminating compounds of silver, mercury, &c., the nature of which was made out byMM. Liebig and Gay Lussac. M. Liebig, upon repeating M. Wohler’s experiments upon his cyanate of silver, obtained only 71.012 per cent. of oxide of silver, instead of 77.23, which was the quantity present according to M. Wohler’s analysis, and concluded that the acid was the cyanous, and not the cyanic. The latter philosopher was consequently induced to repeat his experiments: one of his methods of decomposing the cyanate of silver was by muriatic acid gas: at first liquid cyanic acid forms, which is very soon transformed into a white crystalline mass; but, on continuing the operation, and applying a higher heat, a large quantity of muriate of ammonia and cyanic acid is evolved. This process indicated 77.5 per cent. of oxide of silver in the salt. Another process consisted in dissolving the cyanate in nitric acid, and precipitating the silver by muriatic acid, the result was 77.05 of oxide per cent. A third analysis, made by reducing the silver of the salt, gave a result of 77.35 per cent. oxide. The mean of these is 77.3, and the theoretical number obtained by calculation is 77.23, so that the acid appears to be truly the cyanic; and the curious fact of its being the same in composition with that in the fulminating compounds of silver and mercury, but very unlike in properties, still remains undisturbed.—Bull. Univ., A. viii. 53.8.Iodous Acid.—According to M. Wohler, the iodous acid of[p204]M. Sementini35is nothing more than a mixture of chloride of iodine and iodine. When saturated with carbonate of soda, the iodine in solution is precipitated, and on evaporating the solution to dryness, and heating it strongly, the residue fuses, and by proper tests is found to be a mixture of chloride and iodide of sodium.These statements apply only to the iodous acid: as to the oxide of iodine, no source of chlorine exists in the process last described by M. Sementini.35See the last volume of this Journal, p. 477.9.On Manganesic Acid, byM. Unverdorben.—When manganesate of potash is distilled with a little anhydrous sulphuric acid, manganesic acid is evolved in the form of a red transparent gas, which dissolves in water, forming a red solution. The gas frequently decomposes spontaneously in the retort, with explosion, producing oxide of manganese and oxygen.Manganesate of potash was analysed by distilling it with excess of sulphuric acid, collecting the oxygen disengaged, and estimating the proportion of protoxide of manganese and salts of potash remaining in the retort. According to these experiments the acid consists ofManganese58.74Oxygen41.26100.00And themanganesateof potash ofOr beingcalcinedPotash25.6332.75Manganese acid52.4467.25Water21.93100.00100.00Ann. des Mines, 1827, p. 145.10.Heavy Muriatic Ether, and Hydrocarburet of Chlorine or Chloric Ether.—Some comparative experiments have been made on these two substances by M. Vogel. He prepared the former of them by passing chlorine gas into alcohol. The muriatic acid was then separated by distilling the fluid from off chalk, in which operation the muriatic ether and alcohol passed over together, and these were divided by the addition of water, which dissolved the latter, and left the former. The chloric ether was made as usual from chlorine and olefiant gases. The results that were obtained by acting on these substances by a high temperature, potash, phosphorus, &c., induced M. Vogel to consider them as identical in composition, notwithstanding some differences in their physical properties; the specific gravity of the muriatic ether was 1.134, that of the chloric ether 1.214, and the odour of the latter is more aromatic, and the taste more sweet than of the former.Whilst passing the chlorine into the alcohol, M. Vogel observed[p205]that if the sun shone upon the substances when the action was nearly complete, each bubble of chlorine as it entered the alcohol produced a bright purple flame, a dense white vapour, and caused violent concussions in the liquid; another curious instance, in addition to the many that are known, of the power of solar light over chemical action.—Journ. de Pharm.1826, p. 627.11.Test for the Presence of Nitric Acid.—The following method is one devised by Dr. Liebig, for the detection of this substance, which it will effect, he says, when there is not more than a four-hundredth part of the acid present. The liquid to be examined must be mixed with sufficient sulphuric solution of indigo to acquire a distinct blue colour, a few drops of sulphuric acid added, and the whole boiled. If the liquid contains a nitrate, it will be bleached, or, if the quantity is very small, rendered yellow. By adding a little muriate of soda to the liquid before applying heat, a five-hundredth of nitric acid may easily be discovered.—Ann. de Chimie, xxxv. 80.12.Peculiar Formation of Nitre.—The leaves and stems of beet root contain oxalate and malate of potash. Some leaves were tied together and hung up in a warm and slightly-humid place, where there was but little light, to dry. Being examined at the end of several months, they were found penetrated with, and covered by, an immense number of minute crystals of nitre. The oxalic and malic acids had been replaced by nitric acid; but whether from animalized matter naturally in the leaves of the plant, or from the action of the air, or in what manner, is not known.—M.HENRIBRACONNOT,Ann. de Chimie, xxxv. 260.13.Experiments on Fluoric Acid and Fluates, byM. Kuhlman.—These experiments were made with dry sulphuric acid and fluor spar, with the intention of proving that fluor spar is truly a compound of fluorine and calcium, and not of fluoric acid and oxide of calcium. A quantity of anhydrous sulphuric acid was prepared with great care, and collected in a glass tube; the latter was then connected with a platina tube charged with fluor spar, which had previously been calcined in a platina crucible, and a glass tube was connected with the other end of the platina tube for the purpose of conducting and facilitating the collection of the gas evolved over mercury. The fluor spar was heated to redness, and then the temperature of the sulphuric acid raised so as to cause a stream of it in vapour to pass over the fluor spar; but there was not the slightest reaction, the sulphuric acid recondensed in part in the farthest tube, and no trace of fluoric acid was produced. Dry sulphuric acid was then put, in the liquid state, in contact with dry fluor spar, but there was no decomposition, and no portion of the spar was converted[p206]into sulphate of lime. The first experiment was then repeated, with the difference of using hydrated sulphuric acid of specific gravity 1.842, and there was instantly much fluoric acid produced, which acted upon the glass.As Berzelius found 100 parts of fluor spar, when acted upon by sulphuric acid, to yield 175 parts of sulphate of lime, equal to 73.553 parts of lime, or 52.819 of calcium, it follows that 100 parts of fluoride of calcium should contain 47.181 of fluorine and 52.819 of calcium. By the assistance of this result, and further experiments, M. Kuhlman proceeded to ascertain the composition of hydro-fluoric acid. Dry muriatic acid gas was passed over calcined fluor spar heated to redness in a tube of platina; the fluoride of calcium was decomposed, free hydro-fluoric acid was evolved, and chloride of lime remained in the tube. The hydro-fluoric acid acted upon the glass tubes, but being received in water was entirely dissolved, with the exception of the silica it had separated from the glass: no trace of hydrogen appeared. One hundred parts of fluoride of calcium thus treated became 143.417 parts of chloride of calcium, the 52.819 parts of calcium having united to 90.598 parts of chlorine. But this latter quantity must have liberated 2.511 parts of hydrogen, which must, therefore, have combined with the 47.181 parts of fluorine in the spar, to form 49.692 parts of hydro-fluoric acid. This latter body, therefore, consists of 94.941 fluorine, and 5.059 of hydrogen per cent. A small quantity of chlorine was set at liberty during the experiment, the author thinks, from a little manganese in the fluor spar.M. Kuhlman found that all the chlorides, when subjected to the action of anhydrous sulphuric acid in vapour, resisted decomposition, except the chloride of sodium, which gave a small quantity of sulphate of soda, and a double salt of soda and platina, crystallizing in fine needles of a yellow colour. No doubt is entertained that, in the latter case, the common salt and sulphuric acid were not perfectly dry.—Bull. Univ.14.Crystallization of Phosphorous.—By the fusion and careful refrigeration of a large quantity of phosphorus, M. Frantween has obtained very fine crystals of an octoedral form, and as large in size as a cherry-stone.15.Solutions of Phosphorus in Oils.—The solutions of phosphorus in fixed oils are so luminous as often to be resorted to for the exhibition of this peculiar property of phosphorus; but M. Walcker has remarked, that the power which they ordinarily possess is instantaneously destroyed by the addition of small quantities only of certain other substances, as the essential oils. The rectified oils of turpentine and amber, the oils of rosemary, bergamotte, lemon, camomile, angelica root, juniper berries, and parsley seed,[p207]the oil obtained by the distillation of the nutmeg, all produce this effect when their quantity is not more than one-fiftieth part of the luminous oily solution of phosphorus. The same effect is produced by adding about a fifth of the oils of anniseed, cajeput, lavender, rue, sassafras, fern, cascarilla, mint, orange flowers, fennel, valerian, cherry laurel, or bitter almonds, or balsam of copaiba; but the oil of cinnamon, rectified petroleum, balsam of Peru, and camphor, have no such effect.—Annal. der Phys.1826, p. 125.16.On the Inflammation of Powder when struck by Brass, &c.—Iron has been excluded from powder-works as subject to cause sparks by a blow, and brass and copper have been recommended in its place. M. le Col. Aubert has remarked, that brass on brass can inflame powder, and has made experiments on the subject before a committee, the result of which is as follows:—Inflammation of the powder takes place when the blow is given by iron against iron; iron against brass; brass against brass; iron against marble; lead against lead, or against wood, when the blow is produced by a leaden ball shot from a fire-arm. As yet the powder has not been inflamed by the blow of an iron hammer against lead or wood.—Bull. de la Soc. d’Encouragement;Bull. Univ.17.Cementation of Iron by Cast Iron.—Pure iron, when surrounded by, and in contact with, cast iron turnings, and heated, is carbonised very rapidly, so as to harden, to temper, and, in fact, to exhibit all the properties of steel. M. Gautier finds this a very advantageous process in numerous cases, especially where the articles to be case-hardened, or converted into steel, are small, as iron wire, or wire gauze. The temperature required is not so high as that necessary in the ordinary process of cementation, and the pieces to be carbonised are not injured in form. The kind of cast iron used should be the gray metal, and the more minutely it is divided the more rapid and complete is the operation. By covering the mass of cast metal, in which the iron to be carbonised is enveloped, with sand, oxidation, from contact of the air, is prevented, and the cast metal may be used many times. Plumbago experimented with in the same manner does not produce the effect.—Jour. de Pharmacie, 1827, p. 18.18.On the Preparation of Ferro-prussiate of Potash, byM. Gautier.—Numerous investigations induced M. Gautier to conclude, that, i. When animal matter is calcined alone it yields but little cyanogen. ii. That when mixed with potash it gives more, but the cyanuret is not ferruretted. iii. That ammonia is then produced in large quantity. iv. That the substitution of nitre for potash, and the addition of iron or scales of iron, augmented the production of cyanogen, and gave a ferro-prussiate. The following is the process of manufacture to which M. Gautier has ultimately arrived,[p208]and which he has practised for some years. The proportions of the materials are—Blood, consideredas in the dry state,3 partsNitre1 partIron scales150of the bloodemployed.The blood is first to be coagulated in a large copper cauldron, and the serum being separated by means of a press, the coagulum is to be returned to the cauldron with the nitre and iron. The quantity of water contained in the blood is sufficient to liquify the salt, so as to allow of an uniform mixture being effected. The mixture is then removed, and exposed in an airy situation to dry, the putrefaction of the blood being prevented by the nitre. When the desiccation is complete, the mixture is charged into cast iron cylinders, which are fixed in a reverberatory furnace, and in all things resemble those used in the preparation of animal charcoal. These are to be raised to a brown red heat, until no more vapour is disengaged, and then left until nearly cold, after which the contents are to be withdrawn and put into a wooden vat, with twelve or fifteen times their weight of water, for an hour. The fluid is then to be filtered through a cloth, and evaporated until of 32° of Beaué (specific gravity 1.284.) Being then left to cool, a large quantity of well-crystallized bi-carbonate of potash is obtained. M. Gautier says he has not, as yet, been able to explain how it is that this bi-carbonate has been formed at so high a temperature; a portion also appears to be decomposed during the evaporation of the solution, which, at first but slightly alkaline, becomes sensibly so by a prolonged evaporation.As the same product is not obtained when potash is used in place of nitre, it is probable that the elements of the nitric acid perform a particular part in the operation.The solution which has given the crystals of carbonate of potash contains a little carbonate of potash, and much ferro-prussiate of potash. It is to be concentrated to 34° (specific gravity 1.306), and placed in wooden vessels lined with lead. In the course of some days a greenish crystalline mass is obtained, which being redissolved in a fresh quantity of pure water, and evaporated to 32° or 33° (specific gravity 1.295), is to be recrystallized.Sometimes, when using potash, M. Gautier has mixed nitre with it, and has always obtained a richer product than when potash alone had been employed.—Jour. de Phar.1827, p. 11.19.Sulphocyanide of Potassium in Saliva.—MM. Tiedemann and Gmelin have observed the existence of this peculiar compound in saliva, in two cases; the one when the fluid was secreted during smoking, and the other when no such stimulus was applied.—Ann. de Chimie, xxxv. 266.20.Decomposition of Sulphate of Copper by Tartaric Acid.—M.[p209]Planche has observed, that when sulphate of copper is dissolved in wine vinegar, for the purpose of preparing a corrosive liquid to be applied to corns on the feet, that the tartaric acid present in the vinegar displaces the sulphuric acid from a part of the salt, and an insoluble acid tartrate of copper is produced.21.Separation of Arsenic from Nickel or Cobalt.—The following process by M. Woehler seems among the best of those intended for freeing nickel or cobalt from arsenic in the dry way. It is founded upon the circumstances that many alloys, when heated with sulphuret of potash, become changed into a mixture of sulphurets, and that sulphuret of arsenic is very soluble in sulphuret of potash. One part of kupfernickle, fused and reduced to fine powder, is to be mixed with 3 parts of carbonate of potash, and 3 parts of sulphur, in a covered Hessian crucible. The heat is to be gradually raised to redness, and until the mass is just entering into fusion, and by no means so highly as to fuse the sulphuret of nickel which is formed. When cold, water is to be added, which will dissolve the sulphuret of potash, and leave a yellow crystalline powder, which is sulphuret of nickel, retaining, perhaps, a little copper or cobalt, but no arsenic, if the operation has been well performed. When, however, the object is to have the nickel perfectly pure, it should be fused a second time with sulphur and potash.The method of freeing cobalt from arsenic, is the same as for nickel; but it is then necessary to perform the operation a second time. The cobalt (that of Tunaberg) has never been perfectly freed from arsenic by one operation, but has never retained any after the second.—Archiv für Bergbau, 1826, p. 186.22.Compounds of Gold.—According to late experiments of Dr. Thomson, peroxide of gold consists of1 atom gold253 " oxygen328and is consequently a teroxide. Muriate of gold consists of2 atoms muriatic acid9.251 " per oxide of gold28.5 " water5.62542.875Edin. Journal, p. 182.23.Chemical Researches relative to certain Ancient Substances.—M. Vauquelin has analyzed, i. A poignard blade formed of copper only; ii. A mirror, which was found to consist of 85 parts of copper, 14 of tin, and 1 of iron per cent.; iii. A blue colour found in a tomb:[p210]it was composed of silica 70 parts; lime 9; oxide of copper 15; oxide of iron 1; soda mixed with potash 4. A blue identical with this, both in colour and composition, was found in the bottom of a furnace in which copper had been fused at Romilly.M. D’Arcet has examined a bone from the fore part of an ox, which had been placed as an offering to the divinity in an Egyptian tomb, and found that it contained as much gelatine as recent bone, although rather less is obtained by muriatic acid, (20 per cent. instead of 27) because of a deterioration of the bone. When burnt, it gave an animal black as deep in colour as that from recent bone.M. Le Baillif has examined some grains of corn, which were so well preserved, that when put into boiling water iodine produced the blue colour dependent upon starch. He also made some experiments on a gummy substance, and on two cords from a musical instrument; the latter were of animal substance.M. Raspail examined some grain which was supposed to be wheat, but found it to be torrified barley; it was covered with a substance communicated probably by the oil and incense with which the grains were bathed when consecrated. Similar grains were obtained by roasting common barley.The account of most of these researches is given in the Catalogue raisonné et historique des Antiquités découvertes en Egypte, by M. Passalacqua.—Bull. Univ.A. vii. 264.24.On the Bitter Substance produced by the action of Nitric Acid on Indigo, Silk, and Aloes,byM. Just Liebeg.—The process by which M. Liebeg obtains a pure and uniform substance from the action of nitric acid on indigo, is as follows:—A portion of the best indigo is to be broken into small fragments, and moderately heated with eight or ten times its weight of nitric acid of moderate strength. It will dissolve, evolving an abundance of nitrous vapours and swelling up in the vessel. After the scum has fallen, the liquid is to be boiled, and nitric acid added, whilst any disengagement of red vapours is occasioned by it. When the liquid has become cold, a large quantity of semi-transparent yellow crystals will be formed, and if the operation has been well conducted, no artificial tannin or resin will be obtained. The crystals are to be washed with cold water, and then boiled in water sufficient to dissolve them. If any oily drops of tannin form on the surface of the solution, they must be carefully removed by touching them with filtering paper. Then filtering the fluid, and allowing it to cool, yellow brilliant crystalline plates will be obtained, which will not lose their lustre by washing.To obtain the substance perfectly pure, the crystals must be re-dissolved in boiling water, and neutralized by carbonate of potash. Upon cooling, a salt of potash will crystallize, which should be purified by repeated crystallizations.On mixing the first mother liquor with water, a considerable brown precipitate will be obtained, which being dissolved in boiling[p211]water, and neutralized by carbonate of potash, will furnish a large quantity of the potash salt. All the potash salt obtained in these operations is to be re-dissolved in boiling water, and nitric, muriatic, or sulphuric acid added; as the solution cools, the peculiar substance will be observed to form very brilliant plates of a clear yellow colour, generally in equilateral triangular forms.Sometimes crystals are not formed after the action of the nitric acid on the indigo, in which case the liquor must be evaporated, and water added, when the substance will precipitate, and must be purified as already described. Four parts of indigo yield one of the pure substance.When the substance is heated, it fuses, and is volatilized without decomposition; when subjected to a sudden strong heat, it inflames without explosion, its vapours burning with a yellow flame, and a carbonaceous residue remaining. It is but little soluble in cold water, but much more in boiling water; the solution has a bright yellow colour, reddens litmus, has an extremely bitter taste, and acts like a strong acid on metallic oxides, dissolving them, and forming peculiar crystallizable salts.—Ether and alcohol dissolve the substance readily.When fused in chlorine or with iodine, it is not decomposed, nor does solution of chlorine affect it. Cold sulphuric acid has no action on it; when hot, it dissolves it, but water separates the substance without alteration. Boiling muriatic acid does not affect it, and nitro-muriatic acid only with great difficulty.These results show that no nitric acid is present in the substance, and other experiments prove that no oxide of nitrogen exists in it; it contains no oxalic or other organic acid, for when its salt is boiled with chloride of gold, the latter is not reduced.When heated to redness with oxide of copper, it gave a mixture of nitrogen and carbonic acid, in the exact proportion of 1 volume of the former, to 5 of the latter. This was a constant result, and in no case was any sulphuric or muriatic acid left in the copper. 0.0625 grammes of the substance thus decomposed, gave 45 cubic centimeters of the mixed gases, estimated at 0° C. (32° F.) and the pressure of 28 inches of mercury, according to which the acid would be composed of carbon 32.392; nitrogen 15.2144; oxygen 52.3936 per cent. From the mean of several experiments, it appeared that the following might represent the compositioncorrectly.—1212atoms of carbon93.75or31.5128212" azote43.75"14.706016 " oxygen160.00"53.7812297.5100.100 parts of the acid neutralize a quantity of base equivalent to 3.26 of oxygen, which is to the oxygen of the acid, as 1:16; the equivalent number of the acid derived from the analysis of the[p212]barytic salt was 306.3; by adding only14per cent. to the quantity of baryta obtained in the experiment, 297.5, or the number expressed by the above formula, would be obtained.When a salt of potash or baryta was decomposed by oxide of copper and heat, the quantity of carbonic acid produced was a little short of five times the quantity of nitrogen; but, upon adding that retained by the alkali or earth, the proportion became exactly the same as in the former cases.Welter’s bitter principlewas prepared by acting on silk with ten or twelve times its weight of nitric acid. The liquid, slightly coloured at first, acquired a deep yellow upon adding water. It was neutralized by carbonate of potash whilst hot, and left to cool, and the salt of potash thus obtained, decomposed by muriatic, nitric, or sulphuric acid. This acid, crystallized like that from indigo, formed the same salts, and was composed in the same manner. Silk furnishes much less of the substance than indigo. Dr. Liebeg has called this substancecarbazotic acid. The most important salts formed by it have the followingproperties:—Carbazotate of Potash—crystallizes in long yellow quadrilateral needles, semi-transparent and very brilliant; it dissolves in 260 parts of water at 59° F., and in much less, boiling water: a saturated boiling solution becomes a yellow mass of needles, from which scarcely any fluid will run. Strong acids decompose it; yet when an alcoholic solution of carbazotic acid is added to a solution of nitre, crystallized carbazotate of potash, after some time, precipitates.—Alcohol does not dissolve it. When a little is gradually heated in a glass tube, it first fuses, and then suddenly explodes, breaking the tube to atoms; traces of charcoal are observed on the fragments. This salt precipitates a solution of the protonitrate of mercury, but not salts, containing the peroxide, or those of copper, lead, cobalt, iron, lime, baryta, strontia, or magnesia. The slight solubility of this salt supplies an easy method of testing and separating potash in a fluid. Even the potash in tincture of litmus may be discovered by it; for, on adding a few drops of carbazotic acid, dissolved in alcohol, to infusion of litmus, crystals of the salt gradually separated. The saturated solution of the salt at 50° F., is not troubled by muriate of platina. The salt contains no water of crystallization. It was analyzed by converting a portion of it into chloride of potassium by muriatic acid: its compositionis,—Carbazotic acid83.79Potash16.21100.00Carbazotate of Soda—crystallizes in fine silky yellow needles, having the general properties of the salt of potash, but soluble in from 20 to 24 parts of water, at 59° F.Carbazotate of Ammoniaforms very long, flattened, brilliant,[p213]yellow crystals, very soluble in water. Heated carefully in a glass tube, it fuses, and is volatilized without decomposition; heated suddenly, it inflames without explosion, and leaves much carbonaceous residue.Carbazotate of Baryta, obtained by heating carbonate of baryta, and carbazotic acid with water. It crystallizes in quadrangular prisms of a deep colour, and dissolves easily in water. When heated, it fuses, and is decomposed with very powerful explosion, producing a vivid yellow flame. The explosion is as powerful as that of fulminating silver; a solution of chloride of potassium to which carbazotate of baryta has been added, produces a precipitate of the potash salt, and not more than112per cent. of potash remains in solution. 100 parts of the crystallized saltcontain,—Carbazotic acid69.16oxygen of the acid16Baryta21.60oxygen of the earth1Water9.24oxygen of the water8100.00Carbazotate of Lime, obtained like the salt of baryta, forms flattened quadrangular prisms, very soluble in water, and detonating like the salt of potash.Carbazotate of Magnesiaforms very long indistinct needles, of a clear yellow colour; is very soluble, and detonates violently.Carbazotate of Copper, prepared by decomposing sulphate of copper by carbazotate of baryta: it crystallizes with difficulty, the crystals being of a fine green colour; it is deliquescent; when heated, it is decomposed without explosion, and even without inflammation.Carbazotate of Silver.—Carbazotic acid readily dissolves oxide of silver, when heated with it and water; and the solution, gradually evaporated, yields starry groups of fine acicular crystals of the colour and lustre of gold; the salt dissolves readily in water; when heated to a certain degree, it does not detonate, but fuses like gunpowder.Proto-Carbazotate of Mercury, obtained in small yellow triangular crystals, by mixing boiling solutions of the carbazotate of potash or soda, and proto-nitrate of mercury. It requires more than 1200 parts of water for its solution: for its perfect purification, it should be heated with a solution of chloride of potassium, the insoluble portion separated whilst the liquid is lost, and the peculiar salt allowed to deposit as the temperature falls. When heated, it behaves like the salt of silver.All these salts detonate much more powerfully when heated in close vessels, than when heated in the air; and it was a curious thing to observe, that those with bases yielding oxygen most readily, were those which exploded with least force. By heating some of the salts previously mixed with chloride of potassium, &c., to retard the action, it appeared that no carbonic oxide, but only carbonic[p214]acid and azote were evolved during their decomposition by heat.On the Bitter Principle from Aloes.—Upon distilling 8 parts of nitric acid from 1 part of the extract of aloes, and adding water to the remaining fluid, a resinous reddish yellow substance precipitated, which, by washing, became pulverulent—it was discovered by M. Braconnot. Upon evaporating the liquid separated from the precipitate, it gave large yellow rhomboidal crystals, not transparent, and but slightly soluble. These crystals, at first mistaken for a particular substance, were soon found to be a combination of oxalic acid with the bitter of aloes. The bitter substances of aloes dissolved in 800 parts of water, at 59° F., but in a smaller quantity of boiling water. This solution has a superb purple colour. Silk boiled in it acquired a very fine purple colour, on which neither soap nor acids effected any change, except nitric acid; this changed the colour to yellow, but it was restored simply by washing in water. All shades may be given to this colour by proper mordants. Wool is dyed black in a peculiarly beautiful manner, by the same process, and light has no influence on the colour. Leather acquires a purple colour; cotton, a rose colour; but the latter will not resist soap. Dr. Liebeg thinks that this is the only substance from which a permanent rose dye for silk may be expected.—Ann. de Chimie, xxxv. 72.25.On the Existence of Crystals of Oxalate of Lime in Plants.—M. Raspail has read a memoir to the Academy of Sciences, to prove the analogy which exists in arrangement between the crystals of silica, which are found in sponges, and those of oxalate of lime occurring in the tissue of phanerogamous plants.The latter crystals were observed, for the first time, by Rafn and Jurine, who regarded them as organs of which they knew not the use. They were then observed by M. de Candolle, who called themraphides, and gave a figure of them, which, however, is inaccurate. These crystals are really very regular tetraedrons. In many plants, asorchis,pandanus,ornithogalum,jacinthus,phytolacadecandria,mesembryanthemum deltoides, &c. they are very small, not being more than1200of a millimetre (.0002 of an inch) in width, and110(.004 of an inch) in length. But, in the tubercles of the Florence iris, they are as much as150(.0008 of an inch) in width, and13(.01312 of an inch) in length, so as to be easily capable of examination.—Bull. Univ.B. xi. 376.26.Fallacy of Infusion of Litmus as a Test,byM. Magnus.—When pure water is heated for a sufficient time with infusion of litmus, reddened by an acid, it restores the blue colour. It is supposed that the heat gradually causes the free sulphuric acid, which had occasioned the reddening, to combine with the excess of alkali contained in the infusion, and thus to cause the restoration of the blue colour. Hence this preparation cannot be used to test the[p215]presence of ammonia in a solution, as water alone produces the effect anticipated from the alkali. The earthy salts contained in ordinary water also produce this effect.—Jour. de Pharmacie.27.Tests for the Natural Colouring Matter of Wine.—M. A. Chevalier states,—i. That potash may be employed as a re-agent, to ascertain the natural colour of wines, which it changes from red to a bottle green, or brownish green—ii. That the change of colour produced by this substance upon wine is different for wine of different ages—iii. That no precipitation of the colouring matter takes place, the latter remaining dissolved by the potash—iv. That the acetate of lead should not be employed as a test of the colour of wines, because it is capable of producing various colours with wines of a natural colour only—v. That the same is the case with lime-water, with muriate of tin mixed with ammonia, and with subacetate of lead—vi. That ammonia may be employed for this purpose, the changes of colour which it produces not perceptibly varying—vii. That the same is the case with a solution of alum to which a certain quantity of potash has been added, and which may, therefore, be used for the purpose.—Annales de l’Industrie.28.Test of the Presence of Opium.—Dr. Hare says he can detect opium in solution, when the quantity is not more than that given, by adding ten drops of laudanum to half a gallon of water. The following is the process:—a few drops of solution of acetate of lead is to be added to the solution containing the drug; after some time an observable quantity of meconiate of lead will fall down: from six to twelve hours may sometimes be required, and the precipitation is best effected in a conical glass vessel, for then, by gentle stirring now and then to liberate that which adheres to the side, the insoluble salt may be collected together at the bottom. About thirty drops of sulphuric acid are then to be poured on to the meconiate by means of a glass tube, after which as much of a solution of red sulphate of iron is to be added in the same manner. The sulphuric acid will liberate the meconic acid, and thus enable it to produce with the iron the appropriate colour, which demonstrates the presence of that acid, and consequently of opium.—Silliman’s Journal, xii. 290.29.Denarcotized Laudanum.—Thinking it important to ascertain whether, by the removal of narcotine from opium, the unpleasant effects which, according to the opinions at present entertained upon that subject, are produced by that drug would be removed, Dr. Hare prepared some opium with ether, guided by Robiquet’s statement that narcotine was soluble in that fluid: the opium was shaved by rubbing it on the face of a jack-plane, and subjected four times successively to as much ether of the specific gravity 0.735 as would cover it, the operation being performed in a small Papin’s digester, at a temperature near the boiling point of ether, and each[p216]portion of the fluid being allowed twenty-four hours for its action. A crystalline deposition was soon observed in the ether which had been removed from the opium, and, allowing the stopper of the vessel to remain out, nearly the whole of the liquid evaporated in a few days, and left much coloured crystalline matter. This, Dr. Hare has no doubt, was narcotine in an impure state. The opium was afterwards subjected to as much alcohol as would have been required to convert it into laudanum, had it been in the ordinary state; and this being administered medicinally, was found to occasion none of those uneasy and unpleasant sensations which often follow the use of ordinary opium.—Silliman’s Journal, xii. 291.30.Extraction of Morphia from Dry Poppy Heads, by M. Tilloy.—Make an aqueous extract of the heads, add alcohol to the extract, separate the alcoholic solution, and distil it; by this means the gummy matter is separated. An extract like syrup will be obtained by the distillation, which, being heated to make it thinner, and of the consistency of treacle, is to be again treated with alcohol; a separation of more gum, with much nitrate of potash, will be effected. The solution being withdrawn, is to be distilled, and the extract which will remain is to be acted upon by a sufficient quantity of water, and filtered, to separate the resinous matter present. The morphia may then be separated from this liquid, either by ammonia, carbonate of soda, or magnesia. Ammonia does not precipitate all the morphia; carbonate of soda precipitates a large quantity, but, it separates resinous matter also, which is found mingled with the morphia. Magnesia is preferable; but as the liquid contains much free acetic acid, it is expensive to employ the necessary quantity of pure magnesia: the liquid may, therefore, be partly saturated, whilst hot, by carbonate of magnesia, or even by carbonate of lime. A judgment, when no more must be added, must be formed from the effervescence; then pure magnesia is to be added, which will cause the liberation of ammonia; the whole is to be left for twenty-four hours to cool: being then filtered, the precipitate is to be washed, and, when dry, acted upon by alcohol. Operating in this manner, morphia may be obtained from all kinds of poppies.—Bull. Univ.E. viii. 10.31.Preparation of Morphia.—Some curious experiments have been described to the Académie de Médecine, by M. Robinet, relative to the preparation of morphia. Having operated on the residue of opium by muriatic acid, and precipitated the morphia from the muriatic solution by lime, he wished to ascertain whether the mother liquor contained any morphia that had escaped precipitation. He, therefore, passed a current of carbonic acid gas through the solution, to precipitate the lime in excess: this precipitate being washed, dried, and acted upon by alcohol, was found mixed with a very large proportion of morphia, which could[p217]be thus separated. The washings of the precipitate being examined, were found free from morphia.M. Henry observed, at the same time, that, from experiments made at La Pharmacie Centrale, it appeared that much more morphia was obtained in those processes in which lime had been used to precipitate the morphia, than in those in which magnesia had been used.—Bull. Univ.C. xi. 225.32.Easy Method of obtaining Meconic Acid, by Dr. Hare.—If to an aqueous infusion of opium we add subacetate of lead, a copious precipitation of meconiate of lead ensues: this being collected by a filter, and exposed to sulphuretted hydrogen, meconic acid is liberated: the solution is of a reddish amber colour, and furnishes, by evaporation, crystals of the same hue. A very small quantity produces a very striking effect in reddening solution of peroxide of iron. Instead of sulphuretted hydrogen, sulphuric acid may be used to liberate the meconic acid: the presence of the former in excess does not seem to interfere with the power of reddening ferruginous solutions, but any excess of sulphuric acid may be removed by whitening, which is not acted upon sensibly by meconic acid; Yet, the acid procured in this way did not crystallize so handsomely, or with so much facility, as that obtained by sulphuretted hydrogen.33.On a New Vegetable Acid.—This acid is crystallizable, but the forms have not as yet been determined: it is less soluble in cold water than tartaric acid; its aqueous solution precipitates lime water in white floculi, just like tartaric acid, but the precipitate, if dissolved in muriatic acid, re-appears on adding ammonia, whilst that produced by tartaric acid does not produce this effect. The new acid has a greater affinity for lime than muriatic or nitric acids, for it precipitates the muriate and nitrate of this earth in the manner of oxalic acid, but it differs from the latter in not precipitating a solution of sulphate of lime. With potash it forms an acid salt, slightly soluble in cold water: it precipitates acetate of lead, and the precipitate holds much water in combination: the tartrate of lead, on the contrary, is anhydrous. Notwithstanding these circumstances, the equivalent number of this acid is within a few thousandths of that of tartaric acid: when distilled, it is decomposed, and produces an acid yellow liquid like tartaric acid, leaving a light charcoal burning without residuum. M. Gay Lussac is engaged in developing the chemical history of this substance.—Bull. Univ.A. vii. 327.34.Altheine, a new Vegetable Principle.—M. Bacon gives the following directions for the preparation of this substance, which he has discovered in theAlthea officinalis. An extract of the roots of the plant is to be made by means of cold water, and, when concentrated,[p218]acted upon by boiling alcohol: the latter will dissolve the acid malate of altheine, oil, &c.: the different alcoholic decoctions are to be put together and will throw down a crystalline deposite as they cool; the latter is to be separated and dissolved in water, and the solution, when filtered, is to be evaporated by a moderate heat, until like a syrup, and then set aside to crystallize. The crystals procured are to be washed with a small quantity of pure water, to separate the yellow matter from them, and then dried upon paper. These crystals appear, to the naked eye, like grains, needles, and feathers, but under the microscope present a hexaedral form. They are of a fine emerald green colour, transparent, brilliant, inodorous; unaltered in the air; they redden litmus paper, are soluble in water, and insoluble in alcohol. The aqueous solution of these crystals, acted upon by cold magnesia and filtered, then restores the colour of reddened litmus paper; renders syrup of violets green; and when evaporated furnishes the altheine free from malic acid. When thus pure, the substance crystallizes in regular hexaedral forms or in rhomboidal octoedrons; it affects litmus and violets as just described: it is transparent, of an emerald green colour, brilliant, inodorous, slightly sapid, unaltered by air, very soluble in water, not soluble in alcohol, soluble in acetic acid, with which it forms a crystalline salt.—Ann. de Chimie, xxxiv. 201.35.Rheine, a new Substance from Rhubarb.—By acting upon one part of Chinese rhubarb with 8 parts of nitric acid, s. g. 1.32, at a moderate temperature, reducing the whole to the consistence of syrup, and then diffusing it through water, M. Vaudin obtained a precipitate which possessed peculiar characters, and to which he gave the name ofRheine. When dry, it is of an orange yellow colour, without any particular odour, and slightly bitter. It dissolves in water as well as in alcohol and ether: the solutions become yellow by acids, and rose red by alkalis. It burns nearly in the manner of amadou. Rhubarb acted upon by ether only gave a similar substance, a circumstance which proves that Rheine exists ready formed in rhubarb, and that it is not acted upon by nitric acid.—Ann. de Chimie, xxxiv. 192.36.On Dragon’s Blood, and a new Substance which it contains,byM. Melandri.—Pure dragon’s blood is, according to M. Melandri, a scarce substance; the drops in which it occurs are rarely transparent, generally opaque, and with a rough fracture: its colour is blood red. Besides being soluble in alcohol it is entirely soluble in oil and also in hot water, though a large quantity of the latter fluid is required for the purpose. The aqueous solution is bitter, astringent, and of a fine purple colour; by cooling, it becomes milky and red. Gelatine does not alter its appearance; a proof that the substance contains no tannin. Sulphate of iron forms a pale reddish precipitate, so that no evidence of gallic acid is afforded.[p219]Supposing that this substance might contain a principle analogous to that latterly observed by M. Pelletier in logwood, &c. a portion of it was dissolved in strong alcohol, the solution evaporated until very concentrated, and then poured into cold water, an agglomerated spongy substance was precipitated, which, after being washed with cold water and filtered, was triturated with water containing1100thof sulphuric acid, and exhibited traces of chemical action at a temperature of 22° (61°.6 F.) It then deposited a substance upon the sides of the vessel, and the liquid became yellow and very acid. The sediment, being carefully washed with water, was of a fine red colour, varying according to the state of aggregation; it had no taste or smell; was flexible between the fingers, and was quite fluid at 55° (131° F.). This substance, which the author has calledDracine, has some analogy with the vegeto-alkalis, although its affinity for acids is but slight. The sulphate may be obtained, he says, by adding sulphuric acid diluted with alcohol to an alcoholic solution ofdracine, precipitating the mixture by cold water, and then applying a little heat; the sulphate of dracine collects at the bottom, is to be washed with cold water until the latter no longer reddens litmus paper, and then dissolved in hot water. This solution becomes red by the smallest quantity of alkalis, and may be used as a very sensible test of their presence. Dracine is also a good test for acids, assuming a yellow colour with them. The small quantity of carbonate of lime in filtering paper may be detected by sulphate of dracine, the yellow solution instantly becoming red from its action, and thus showing its presence.—Bull. Univ.C. xi. p. 157.37.Purification of Madder, by the Separation of its Yellow Colouring Matter.—The experiments ofMM. Kuhlman, Colin, and Robiquet36, have induced M. G. H. de Kurrer to publish the means which he has resorted to for the purification of madder, by the separation of the yellow colouring matter from it; and thus rendering it more fit to supply the various red, lilac, violet, and brown colours which are required upon wool, silk, cotton and linen. Three tubs or vessels are placed by the side of each other: in summer they may be in the open air under shelter, but in the winter should be placed in an airy cellar where the temperature may be retained at 18° or 20° R. (73° to 77° F.). The first is that in which the soaking and fermentation is to be effected: it should be 2 feet 8 inches deep, and 2 feet 6 inches in diameter, for from fifty to fifty-five pounds of madder. The second, or washing vessel, should be512feet deep, and 3 feet in diameter; it should have three wooden cocks fixed into it, the first 2 feet, the second 3 feet, and the third 4 feet from the bottom. The third tub is for deposition; its height should be412feet, and it should have a cock at112foot from the bottom.[p220]On commencing the operation, 50 or 55 lb. of pulverised madder are to be put into the first vessel, water is to be added, and stirred into the mass until it stands112inch above the madder. The whole is then to be left until fermentation comes on and has formed a coat of madder at the surface; this usually takes place in 36 hours, and at latest in 48 hours, according to the temperature. The mass should now be transferred into the second vessel, which is then to be filled with water, and being left for two hours, the madder will fall to the bottom. The upper cock is then to be opened, after that the second, and then the third; and the water which runs from the two latter is to be put into the third vessel, that the rest of the madder may separate from it. The madder in the second vessel is then to be washed a second, third, or fourth time until the washing water is colourless. Thus purified, the madder may be used in the processes of dyeing, according to the known methods; but it is important in summer that it should be used immediately, that a new (the vinous) fermentation may be avoided. The madder deposited in the third vessel, when washed and deposited, may be used like the rest. The liquid first separated after the fermentation may be used in the preparation of hot indigo baths, &c. instead of madder.—Bull. Univ.P. vii. 352.36See page 239 of the last volume.38.On Indigo and Indigogene, by M. Liebeg.—112part of pure indigo, 2 parts of proto-sulphate of iron,212parts of hydrate of lime, and from 50 to 60 parts of water, were digested together for 24 hours in a close vessel, which had previously been filled with hydrogen. The clear liquor over the sulphate of lime and oxide of iron, had a yellowish red colour, and was separated by a syphon filled with hydrogen, and mixed with diluted muriatic acid, containing some sulphite of ammonia dissolved; a dense white precipitate was formed, becoming blue in the air. This was gathered in a filter without contact of air, and washed with boiled water containing sulphite of ammonia in solution, and dried at 212°, in close vessels, through which a current of hydrogen was continually passed. The upper surface of the mass became of a blue colour, but the lower remained of a dull white.This white substance was called Indigogene. It did not change colour in dry air, but under water became of a deep blue, which by drying, assumed a coppery appearance. The blue substance volatilized by heat without leaving any residue, forming purple vapours, which condensed, when cold, into crystals differing in nothing from sublimed indigo.Indigogenedissolves in alkalis without neutralizing them: it is also soluble in alcohol, but insoluble in water or acids.A given quantity of this indigogene was acted upon by ammonia, and the weight of the undissolved blue portion ascertained, it appeared that the weight of the pure portion dissolved was 0.404 grammes (6.224 grains.) The solution was put into an inverted[p221]jar, over mercury, and oxygen gas gradually passed in until absorption ceased, and then the liquid containing the precipitated indigo was evaporated to dryness at 212°. The weight of the substance was increased to 0.047,i. e.11.5 per cent.Not having obtained indigogeneperfectlypure, M. Liebeg did not attempt to analyze it for the ultimate composition. He remarks, that indigo is, perhaps, the only organic body from which one of its constituent parts may be taken without total decomposition; and which, by oxidation, passes to the state of an indifferent body, having much analogy with peroxides.—Ann. de Chimie, xxxv. 269.39.On the mutual Action of Ethers, and other Substances.—From experiments made by M. Henry, he concludes that when metals easily oxidizable, or oxides which unite with acetic acid, are put into sulphuric ether, they produce larger or smaller quantities of acetates, probably, not by decomposing the sulphuric ether, but the acetic ether which is always mixed with it; and that it is in consequence of the saturation of the acetic acid set free from the ether by this decomposition, that sulphuric ether does not redden litmus paper when evaporated, whereas it acts differently when being slightly heated, the quantity of acetic ether contained in it is allowed to decompose by the action of the air.Nitric and acetic ethers are described as being easily decomposed by the action of many bodies without the assistance of heat, if aided by time. Amongst the products of the action are the acids of the ethers, acetates, and alcohol which dissolves the salts formed.—Jour. de Chimie Méd.40.Faraday’s Chemical Manipulation.—The kindness of a friend at Bristol has pointed out to me an error in the directions relative to alkalimetry, which I have given in the above work: this I am desirous of correcting, and, by permission of Mr. Brande, have the opportunity of doing so in theQuarterly Journal of Science.The mistake, which arose from using the wrong specific gravity of two that were required in calculation, occurs in the paragraphs (599, 600,) but fortunately is prevented from occasioning any experimental error by the directions given in (602). The acid of specific gravity, 1.141, directed to be used, is too strong for the quantities marked upon the tube. The substitution of one of specific gravity 1.127, will correct the error, and may be obtained very nearly by mixing 19 parts, by weight, of strong oil of vitriol, with 81 parts of water.The alterations required may be made in the volume with a pen, as for errors of the press, by reading “1.127” for “1.141” in lines 25 and 30 of page 276, and lines 2 and 13 of page 277; and “nineteen” for “one” in line 27, and “eighty-one” for “four” in line 28 of page 276.—M. F.[p222]
1.On the Specific Heat of Gases, byMM. de la RiveandMarcet.—The principle on which these philosophers proceeded in their researches, was, to expose equal volumes of different gases to an equal source of heat during equal times, and to judge, by the augmentation of elastic force in each gas, the temperature which it had acquired. The apparatus was a kind of manometer, and consisted of a glass balloon to retain the gas, and a bent tube attached to it, which, descending into a vessel of mercury, served to show, by the column of metal within it, what was the elasticity of the gas. This method was adopted, because, i. The gas was not altered in volume by the change of temperature, its elasticity only changing: ii. The temperature was indicated by the gas itself, and not by a thermometer: iii. Water was easily separated previously from the gases, and excluded from the apparatus: iv. All the gases were placed in exactly the same circumstances, so as to render it unnecessary to refer to any calculation for the purpose of comparison.
Two methods of applying heat were resorted to: in one the balloon, containing the gas at a certain temperature, was placed in water at a higher but constant degree, for a certain time (generally4′),and the elevation of temperature noticed: in the other, the balloon with the gas was inclosed in a larger copper balloon, blackened inside, and the space between the two exhausted as much as possible of air; the apparatus being then immersed in warm water, the heat gained access slowly to the gas, and the time of each experiment was increased, at the same time that certain sources of error were avoided.
The gases experimented with were, atmospheric air, oxygen, azote, hydrogen, carbonic acid, olefiant gas, oxide of carbon, nitrous oxide, nitrous gas, sulphuretted hydrogen, ammonia, sulphurous acid, muriatic acid, and cyanogen. Great care was taken in their preparation. The result of the experiment was very unexpected; for, during the five minutes allotted for each, all had acquired the same temperature,—a circumstance which proves that they all have thesame specific heat. The equal volumes of gas at the pressure of 65 centimeters (15.59 inches) and the temperature of20° C.,being exposed to a source of heat at30° C.,acquired a mean temperature of 6.32 degrees in five minutes, the extreme difference, in any of the experiments, not being more than 0.04 of a[p201]degree. One gas only forms an exception to the above statement, namely, hydrogen, which was always heated more than the others, namely, to 6.6 degrees in the five minutes. This effect is considered as due not to any difference in specific heat, but to a difference in conducting power.
Experiments were then made with dilated gases, to ascertain whether dilatation caused any change in capacity, and it was found to diminish slowly but regularly with the diminution of pressure. These results, with a third which is also interesting, have been thus generally expressed by the authors at the end of their memoir.
i. All gases in equal volumes, and at the same pressure, have the same specific heat.
ii. Other circumstances being the same, the specific heat of gases diminishes with diminution of pressure, and equally for all the gases: the progression converges slightly and in a ratio much less than that of the pressures.
iii. Each gas has a different conducting power,i.e., all the gases have not the some power of communicating or receiving heat.—Ann. de Chimie, xxxv. 5.
2.On the Incandescence and Light of Lime.—The experiments made by Lieutenant Drummond upon the light of lime and other earths when highly ignited, with the highly interesting application which he has made of that emitted from lime, to the purpose of geodesical surveys, has induced M. Pleischel to repeat and vary the results. He states that the utmost light is given by lime; the earth being pulverised and exposed on burning charcoal to the heat excited by a jet of oxygen falling upon it. He endeavours to account for the effect, by supposing a kind of pulverulent atmosphere disengaged from the lime at the high temperature used, and considers that the substances which are competent to emit molecules only in the gaseous state, cannot produce this intense light.—Zeitschrift für Physik, &c.
3.Evolution of Heat during the Compression of Water. May 14, 1827.—M. Arago announced to the Academy of Sciences, that M. Despretz had ascertained experimentally, that the compression of water by a force equal to 20 atmospheres, caused the disengagement of one sixty-sixth part of a degree of heat.
4.On Electrical Excitation.—M. Walcker affirms positively from experiments made with great care, that three bodies of different exciting power are necessary, in every case of excitation of electricity by contact, and that all the phenomena of this kind are subject to this condition. If, for instance, two portions of the same metal being put in contact, electricity is produced, it is because there are three different states of temperature brought into play, one being the result of the other two, and a mean between them. One fact which more than any other sanctioned this idea, was, that the electric[p202]currents were the more apparent as this third state of temperature was made more sensible.—Bull. Univ., A. vii. 374.
5.Magnetic Repulsion.—A very remarkable result has been obtained by M. Becquerel, from the use of an extremely delicate magnetic arrangement, which he has for the present called asideroscope. Its use is exactly the same in principle as that of the magnetic needle, indicating iron, for instance, by the attraction manifested; but it is so delicate that it will show it in the most minute quantity possible, as, for instance, in gold, silver, or copper money, innumerable minerals, &c. This instrument shows no magnetic power or attraction in gold, silver, copper, palladium, tin, lead, zinc, or brass, when chemically pure, and a great many vegetable and mineral substances have no action on it: but the most curious result is, that very pure bismuth and even that of commerce has arepulsivepower, which, if it be found ultimately to be independent of any magneticpolarity, is the first fact of the kind that has been made known. Antimony also presents the same phenomenon.
6.Diminished Solubility of Substances by Heat.—Mr. Graham has added one to the few facts of this kind with which we were acquainted, and has accompanied its description with some very interesting considerations, which may be found at length in the Philosophical Magazine, N. S., ii. 20. The salt experimented with by Mr. Graham is the phosphate of magnesia; which may be prepared by mixing a solution of 21 parts of phosphate of soda with one of 15.375 parts of sulphate of magnesia: within 24 hours the phosphate of magnesia precipitates in acicular crystals; they should be agitated with repeated portions of water, then thrown upon a filter with more water, and left to dry.
Solutions were obtained by occasionally agitating this salt with water in the proportion of 2 ounces to a pint of the fluid, for four days; being then decanted and filtered, they had a sweetish taste. A quantity of this fluid being heated in a water-bath, became turbid before the temperature had attained120° F.;at212°a cloudy precipitate slowly subsided, and the supernatant fluid became nearly transparent. The precipitate was found to be anhydrous phosphate of magnesia; and, by further experiment, the difference in solubility was found to be such, that water at 45°, dissolving1744thpart its weight of the anhydrous salt, water at 212° only dissolved11151thpart. When in the state of crystals, or as hydrate, the proportions of salt were1322and1498to 1 of water.
Mere continuance of the heat had no effect in increasing the precipitate either of this salt, or from aqueous solution of lime, provided no part of the solution was at any time converted into vapour; but if the solution only occupied a small part of the vessel, and ebullition came on, then, although all the water might be returned to the solution, yet the precipitation went on, and might be[p203]increasedad libitum, particularly in the case of lime water. The cause of the precipitate appears to be the same in all these cases. The moment a drop of the solution is converted into vapour, it deposits the quantity of lime or salt which it held in solution; and in the case of bodies which dissolve so sparingly and with so much difficulty, although the water be returned again to the solution, it is incapable of re-dissolving what it has deposited. We know that it would be a hopeless task to form a saturated solution of lime by agitating with the water no more than the few grains which it is capable of dissolving; and in the case of ebullition, when the lime is once deposited, there should be the same difficulty in taking it up.
Mr. Graham states that he has observed this effect not only in lime-water and in solution of phosphate of magnesia, but to a certain extent in all bodies of difficult solubility, in the sulphate of lime, for instance, even when greatly diluted; and he believes that the deposite from slight boiling observed in many mineral waters, and generally attributed to the dissipation of carbonic acid gas, depends, in some instances, upon this cause. However weak the solution may be, it is evident that a portion of the salt may be deposited in this way.
7.On the Composition of Cyanic Acid.—M. Wohler some time since announced the production of cyanic acid, and cyanates, corresponding in composition to the substance presumed to exist in the fulminating compounds of silver, mercury, &c., the nature of which was made out byMM. Liebig and Gay Lussac. M. Liebig, upon repeating M. Wohler’s experiments upon his cyanate of silver, obtained only 71.012 per cent. of oxide of silver, instead of 77.23, which was the quantity present according to M. Wohler’s analysis, and concluded that the acid was the cyanous, and not the cyanic. The latter philosopher was consequently induced to repeat his experiments: one of his methods of decomposing the cyanate of silver was by muriatic acid gas: at first liquid cyanic acid forms, which is very soon transformed into a white crystalline mass; but, on continuing the operation, and applying a higher heat, a large quantity of muriate of ammonia and cyanic acid is evolved. This process indicated 77.5 per cent. of oxide of silver in the salt. Another process consisted in dissolving the cyanate in nitric acid, and precipitating the silver by muriatic acid, the result was 77.05 of oxide per cent. A third analysis, made by reducing the silver of the salt, gave a result of 77.35 per cent. oxide. The mean of these is 77.3, and the theoretical number obtained by calculation is 77.23, so that the acid appears to be truly the cyanic; and the curious fact of its being the same in composition with that in the fulminating compounds of silver and mercury, but very unlike in properties, still remains undisturbed.—Bull. Univ., A. viii. 53.
8.Iodous Acid.—According to M. Wohler, the iodous acid of[p204]M. Sementini35is nothing more than a mixture of chloride of iodine and iodine. When saturated with carbonate of soda, the iodine in solution is precipitated, and on evaporating the solution to dryness, and heating it strongly, the residue fuses, and by proper tests is found to be a mixture of chloride and iodide of sodium.
These statements apply only to the iodous acid: as to the oxide of iodine, no source of chlorine exists in the process last described by M. Sementini.
35See the last volume of this Journal, p. 477.
35See the last volume of this Journal, p. 477.
9.On Manganesic Acid, byM. Unverdorben.—When manganesate of potash is distilled with a little anhydrous sulphuric acid, manganesic acid is evolved in the form of a red transparent gas, which dissolves in water, forming a red solution. The gas frequently decomposes spontaneously in the retort, with explosion, producing oxide of manganese and oxygen.
Manganesate of potash was analysed by distilling it with excess of sulphuric acid, collecting the oxygen disengaged, and estimating the proportion of protoxide of manganese and salts of potash remaining in the retort. According to these experiments the acid consists of
Manganese58.74Oxygen41.26100.00
And themanganesateof potash ofOr beingcalcinedPotash25.6332.75Manganese acid52.4467.25Water21.93100.00100.00
Ann. des Mines, 1827, p. 145.
10.Heavy Muriatic Ether, and Hydrocarburet of Chlorine or Chloric Ether.—Some comparative experiments have been made on these two substances by M. Vogel. He prepared the former of them by passing chlorine gas into alcohol. The muriatic acid was then separated by distilling the fluid from off chalk, in which operation the muriatic ether and alcohol passed over together, and these were divided by the addition of water, which dissolved the latter, and left the former. The chloric ether was made as usual from chlorine and olefiant gases. The results that were obtained by acting on these substances by a high temperature, potash, phosphorus, &c., induced M. Vogel to consider them as identical in composition, notwithstanding some differences in their physical properties; the specific gravity of the muriatic ether was 1.134, that of the chloric ether 1.214, and the odour of the latter is more aromatic, and the taste more sweet than of the former.
Whilst passing the chlorine into the alcohol, M. Vogel observed[p205]that if the sun shone upon the substances when the action was nearly complete, each bubble of chlorine as it entered the alcohol produced a bright purple flame, a dense white vapour, and caused violent concussions in the liquid; another curious instance, in addition to the many that are known, of the power of solar light over chemical action.—Journ. de Pharm.1826, p. 627.
11.Test for the Presence of Nitric Acid.—The following method is one devised by Dr. Liebig, for the detection of this substance, which it will effect, he says, when there is not more than a four-hundredth part of the acid present. The liquid to be examined must be mixed with sufficient sulphuric solution of indigo to acquire a distinct blue colour, a few drops of sulphuric acid added, and the whole boiled. If the liquid contains a nitrate, it will be bleached, or, if the quantity is very small, rendered yellow. By adding a little muriate of soda to the liquid before applying heat, a five-hundredth of nitric acid may easily be discovered.—Ann. de Chimie, xxxv. 80.
12.Peculiar Formation of Nitre.—The leaves and stems of beet root contain oxalate and malate of potash. Some leaves were tied together and hung up in a warm and slightly-humid place, where there was but little light, to dry. Being examined at the end of several months, they were found penetrated with, and covered by, an immense number of minute crystals of nitre. The oxalic and malic acids had been replaced by nitric acid; but whether from animalized matter naturally in the leaves of the plant, or from the action of the air, or in what manner, is not known.—M.HENRIBRACONNOT,Ann. de Chimie, xxxv. 260.
13.Experiments on Fluoric Acid and Fluates, byM. Kuhlman.—These experiments were made with dry sulphuric acid and fluor spar, with the intention of proving that fluor spar is truly a compound of fluorine and calcium, and not of fluoric acid and oxide of calcium. A quantity of anhydrous sulphuric acid was prepared with great care, and collected in a glass tube; the latter was then connected with a platina tube charged with fluor spar, which had previously been calcined in a platina crucible, and a glass tube was connected with the other end of the platina tube for the purpose of conducting and facilitating the collection of the gas evolved over mercury. The fluor spar was heated to redness, and then the temperature of the sulphuric acid raised so as to cause a stream of it in vapour to pass over the fluor spar; but there was not the slightest reaction, the sulphuric acid recondensed in part in the farthest tube, and no trace of fluoric acid was produced. Dry sulphuric acid was then put, in the liquid state, in contact with dry fluor spar, but there was no decomposition, and no portion of the spar was converted[p206]into sulphate of lime. The first experiment was then repeated, with the difference of using hydrated sulphuric acid of specific gravity 1.842, and there was instantly much fluoric acid produced, which acted upon the glass.
As Berzelius found 100 parts of fluor spar, when acted upon by sulphuric acid, to yield 175 parts of sulphate of lime, equal to 73.553 parts of lime, or 52.819 of calcium, it follows that 100 parts of fluoride of calcium should contain 47.181 of fluorine and 52.819 of calcium. By the assistance of this result, and further experiments, M. Kuhlman proceeded to ascertain the composition of hydro-fluoric acid. Dry muriatic acid gas was passed over calcined fluor spar heated to redness in a tube of platina; the fluoride of calcium was decomposed, free hydro-fluoric acid was evolved, and chloride of lime remained in the tube. The hydro-fluoric acid acted upon the glass tubes, but being received in water was entirely dissolved, with the exception of the silica it had separated from the glass: no trace of hydrogen appeared. One hundred parts of fluoride of calcium thus treated became 143.417 parts of chloride of calcium, the 52.819 parts of calcium having united to 90.598 parts of chlorine. But this latter quantity must have liberated 2.511 parts of hydrogen, which must, therefore, have combined with the 47.181 parts of fluorine in the spar, to form 49.692 parts of hydro-fluoric acid. This latter body, therefore, consists of 94.941 fluorine, and 5.059 of hydrogen per cent. A small quantity of chlorine was set at liberty during the experiment, the author thinks, from a little manganese in the fluor spar.
M. Kuhlman found that all the chlorides, when subjected to the action of anhydrous sulphuric acid in vapour, resisted decomposition, except the chloride of sodium, which gave a small quantity of sulphate of soda, and a double salt of soda and platina, crystallizing in fine needles of a yellow colour. No doubt is entertained that, in the latter case, the common salt and sulphuric acid were not perfectly dry.—Bull. Univ.
14.Crystallization of Phosphorous.—By the fusion and careful refrigeration of a large quantity of phosphorus, M. Frantween has obtained very fine crystals of an octoedral form, and as large in size as a cherry-stone.
15.Solutions of Phosphorus in Oils.—The solutions of phosphorus in fixed oils are so luminous as often to be resorted to for the exhibition of this peculiar property of phosphorus; but M. Walcker has remarked, that the power which they ordinarily possess is instantaneously destroyed by the addition of small quantities only of certain other substances, as the essential oils. The rectified oils of turpentine and amber, the oils of rosemary, bergamotte, lemon, camomile, angelica root, juniper berries, and parsley seed,[p207]the oil obtained by the distillation of the nutmeg, all produce this effect when their quantity is not more than one-fiftieth part of the luminous oily solution of phosphorus. The same effect is produced by adding about a fifth of the oils of anniseed, cajeput, lavender, rue, sassafras, fern, cascarilla, mint, orange flowers, fennel, valerian, cherry laurel, or bitter almonds, or balsam of copaiba; but the oil of cinnamon, rectified petroleum, balsam of Peru, and camphor, have no such effect.—Annal. der Phys.1826, p. 125.
16.On the Inflammation of Powder when struck by Brass, &c.—Iron has been excluded from powder-works as subject to cause sparks by a blow, and brass and copper have been recommended in its place. M. le Col. Aubert has remarked, that brass on brass can inflame powder, and has made experiments on the subject before a committee, the result of which is as follows:—Inflammation of the powder takes place when the blow is given by iron against iron; iron against brass; brass against brass; iron against marble; lead against lead, or against wood, when the blow is produced by a leaden ball shot from a fire-arm. As yet the powder has not been inflamed by the blow of an iron hammer against lead or wood.—Bull. de la Soc. d’Encouragement;Bull. Univ.
17.Cementation of Iron by Cast Iron.—Pure iron, when surrounded by, and in contact with, cast iron turnings, and heated, is carbonised very rapidly, so as to harden, to temper, and, in fact, to exhibit all the properties of steel. M. Gautier finds this a very advantageous process in numerous cases, especially where the articles to be case-hardened, or converted into steel, are small, as iron wire, or wire gauze. The temperature required is not so high as that necessary in the ordinary process of cementation, and the pieces to be carbonised are not injured in form. The kind of cast iron used should be the gray metal, and the more minutely it is divided the more rapid and complete is the operation. By covering the mass of cast metal, in which the iron to be carbonised is enveloped, with sand, oxidation, from contact of the air, is prevented, and the cast metal may be used many times. Plumbago experimented with in the same manner does not produce the effect.—Jour. de Pharmacie, 1827, p. 18.
18.On the Preparation of Ferro-prussiate of Potash, byM. Gautier.—Numerous investigations induced M. Gautier to conclude, that, i. When animal matter is calcined alone it yields but little cyanogen. ii. That when mixed with potash it gives more, but the cyanuret is not ferruretted. iii. That ammonia is then produced in large quantity. iv. That the substitution of nitre for potash, and the addition of iron or scales of iron, augmented the production of cyanogen, and gave a ferro-prussiate. The following is the process of manufacture to which M. Gautier has ultimately arrived,[p208]and which he has practised for some years. The proportions of the materials are—
Blood, consideredas in the dry state,3 partsNitre1 partIron scales150of the bloodemployed.
The blood is first to be coagulated in a large copper cauldron, and the serum being separated by means of a press, the coagulum is to be returned to the cauldron with the nitre and iron. The quantity of water contained in the blood is sufficient to liquify the salt, so as to allow of an uniform mixture being effected. The mixture is then removed, and exposed in an airy situation to dry, the putrefaction of the blood being prevented by the nitre. When the desiccation is complete, the mixture is charged into cast iron cylinders, which are fixed in a reverberatory furnace, and in all things resemble those used in the preparation of animal charcoal. These are to be raised to a brown red heat, until no more vapour is disengaged, and then left until nearly cold, after which the contents are to be withdrawn and put into a wooden vat, with twelve or fifteen times their weight of water, for an hour. The fluid is then to be filtered through a cloth, and evaporated until of 32° of Beaué (specific gravity 1.284.) Being then left to cool, a large quantity of well-crystallized bi-carbonate of potash is obtained. M. Gautier says he has not, as yet, been able to explain how it is that this bi-carbonate has been formed at so high a temperature; a portion also appears to be decomposed during the evaporation of the solution, which, at first but slightly alkaline, becomes sensibly so by a prolonged evaporation.
As the same product is not obtained when potash is used in place of nitre, it is probable that the elements of the nitric acid perform a particular part in the operation.
The solution which has given the crystals of carbonate of potash contains a little carbonate of potash, and much ferro-prussiate of potash. It is to be concentrated to 34° (specific gravity 1.306), and placed in wooden vessels lined with lead. In the course of some days a greenish crystalline mass is obtained, which being redissolved in a fresh quantity of pure water, and evaporated to 32° or 33° (specific gravity 1.295), is to be recrystallized.
Sometimes, when using potash, M. Gautier has mixed nitre with it, and has always obtained a richer product than when potash alone had been employed.—Jour. de Phar.1827, p. 11.
19.Sulphocyanide of Potassium in Saliva.—MM. Tiedemann and Gmelin have observed the existence of this peculiar compound in saliva, in two cases; the one when the fluid was secreted during smoking, and the other when no such stimulus was applied.—Ann. de Chimie, xxxv. 266.
20.Decomposition of Sulphate of Copper by Tartaric Acid.—M.[p209]Planche has observed, that when sulphate of copper is dissolved in wine vinegar, for the purpose of preparing a corrosive liquid to be applied to corns on the feet, that the tartaric acid present in the vinegar displaces the sulphuric acid from a part of the salt, and an insoluble acid tartrate of copper is produced.
21.Separation of Arsenic from Nickel or Cobalt.—The following process by M. Woehler seems among the best of those intended for freeing nickel or cobalt from arsenic in the dry way. It is founded upon the circumstances that many alloys, when heated with sulphuret of potash, become changed into a mixture of sulphurets, and that sulphuret of arsenic is very soluble in sulphuret of potash. One part of kupfernickle, fused and reduced to fine powder, is to be mixed with 3 parts of carbonate of potash, and 3 parts of sulphur, in a covered Hessian crucible. The heat is to be gradually raised to redness, and until the mass is just entering into fusion, and by no means so highly as to fuse the sulphuret of nickel which is formed. When cold, water is to be added, which will dissolve the sulphuret of potash, and leave a yellow crystalline powder, which is sulphuret of nickel, retaining, perhaps, a little copper or cobalt, but no arsenic, if the operation has been well performed. When, however, the object is to have the nickel perfectly pure, it should be fused a second time with sulphur and potash.
The method of freeing cobalt from arsenic, is the same as for nickel; but it is then necessary to perform the operation a second time. The cobalt (that of Tunaberg) has never been perfectly freed from arsenic by one operation, but has never retained any after the second.—Archiv für Bergbau, 1826, p. 186.
22.Compounds of Gold.—According to late experiments of Dr. Thomson, peroxide of gold consists of
1 atom gold253 " oxygen328
and is consequently a teroxide. Muriate of gold consists of
2 atoms muriatic acid9.251 " per oxide of gold28.5 " water5.62542.875
Edin. Journal, p. 182.
23.Chemical Researches relative to certain Ancient Substances.—M. Vauquelin has analyzed, i. A poignard blade formed of copper only; ii. A mirror, which was found to consist of 85 parts of copper, 14 of tin, and 1 of iron per cent.; iii. A blue colour found in a tomb:[p210]it was composed of silica 70 parts; lime 9; oxide of copper 15; oxide of iron 1; soda mixed with potash 4. A blue identical with this, both in colour and composition, was found in the bottom of a furnace in which copper had been fused at Romilly.
M. D’Arcet has examined a bone from the fore part of an ox, which had been placed as an offering to the divinity in an Egyptian tomb, and found that it contained as much gelatine as recent bone, although rather less is obtained by muriatic acid, (20 per cent. instead of 27) because of a deterioration of the bone. When burnt, it gave an animal black as deep in colour as that from recent bone.
M. Le Baillif has examined some grains of corn, which were so well preserved, that when put into boiling water iodine produced the blue colour dependent upon starch. He also made some experiments on a gummy substance, and on two cords from a musical instrument; the latter were of animal substance.
M. Raspail examined some grain which was supposed to be wheat, but found it to be torrified barley; it was covered with a substance communicated probably by the oil and incense with which the grains were bathed when consecrated. Similar grains were obtained by roasting common barley.
The account of most of these researches is given in the Catalogue raisonné et historique des Antiquités découvertes en Egypte, by M. Passalacqua.—Bull. Univ.A. vii. 264.
24.On the Bitter Substance produced by the action of Nitric Acid on Indigo, Silk, and Aloes,byM. Just Liebeg.—The process by which M. Liebeg obtains a pure and uniform substance from the action of nitric acid on indigo, is as follows:—A portion of the best indigo is to be broken into small fragments, and moderately heated with eight or ten times its weight of nitric acid of moderate strength. It will dissolve, evolving an abundance of nitrous vapours and swelling up in the vessel. After the scum has fallen, the liquid is to be boiled, and nitric acid added, whilst any disengagement of red vapours is occasioned by it. When the liquid has become cold, a large quantity of semi-transparent yellow crystals will be formed, and if the operation has been well conducted, no artificial tannin or resin will be obtained. The crystals are to be washed with cold water, and then boiled in water sufficient to dissolve them. If any oily drops of tannin form on the surface of the solution, they must be carefully removed by touching them with filtering paper. Then filtering the fluid, and allowing it to cool, yellow brilliant crystalline plates will be obtained, which will not lose their lustre by washing.
To obtain the substance perfectly pure, the crystals must be re-dissolved in boiling water, and neutralized by carbonate of potash. Upon cooling, a salt of potash will crystallize, which should be purified by repeated crystallizations.
On mixing the first mother liquor with water, a considerable brown precipitate will be obtained, which being dissolved in boiling[p211]water, and neutralized by carbonate of potash, will furnish a large quantity of the potash salt. All the potash salt obtained in these operations is to be re-dissolved in boiling water, and nitric, muriatic, or sulphuric acid added; as the solution cools, the peculiar substance will be observed to form very brilliant plates of a clear yellow colour, generally in equilateral triangular forms.
Sometimes crystals are not formed after the action of the nitric acid on the indigo, in which case the liquor must be evaporated, and water added, when the substance will precipitate, and must be purified as already described. Four parts of indigo yield one of the pure substance.
When the substance is heated, it fuses, and is volatilized without decomposition; when subjected to a sudden strong heat, it inflames without explosion, its vapours burning with a yellow flame, and a carbonaceous residue remaining. It is but little soluble in cold water, but much more in boiling water; the solution has a bright yellow colour, reddens litmus, has an extremely bitter taste, and acts like a strong acid on metallic oxides, dissolving them, and forming peculiar crystallizable salts.—Ether and alcohol dissolve the substance readily.
When fused in chlorine or with iodine, it is not decomposed, nor does solution of chlorine affect it. Cold sulphuric acid has no action on it; when hot, it dissolves it, but water separates the substance without alteration. Boiling muriatic acid does not affect it, and nitro-muriatic acid only with great difficulty.
These results show that no nitric acid is present in the substance, and other experiments prove that no oxide of nitrogen exists in it; it contains no oxalic or other organic acid, for when its salt is boiled with chloride of gold, the latter is not reduced.
When heated to redness with oxide of copper, it gave a mixture of nitrogen and carbonic acid, in the exact proportion of 1 volume of the former, to 5 of the latter. This was a constant result, and in no case was any sulphuric or muriatic acid left in the copper. 0.0625 grammes of the substance thus decomposed, gave 45 cubic centimeters of the mixed gases, estimated at 0° C. (32° F.) and the pressure of 28 inches of mercury, according to which the acid would be composed of carbon 32.392; nitrogen 15.2144; oxygen 52.3936 per cent. From the mean of several experiments, it appeared that the following might represent the compositioncorrectly.—
1212atoms of carbon93.75or31.5128212" azote43.75"14.706016 " oxygen160.00"53.7812297.5100.
100 parts of the acid neutralize a quantity of base equivalent to 3.26 of oxygen, which is to the oxygen of the acid, as 1:16; the equivalent number of the acid derived from the analysis of the[p212]barytic salt was 306.3; by adding only14per cent. to the quantity of baryta obtained in the experiment, 297.5, or the number expressed by the above formula, would be obtained.
When a salt of potash or baryta was decomposed by oxide of copper and heat, the quantity of carbonic acid produced was a little short of five times the quantity of nitrogen; but, upon adding that retained by the alkali or earth, the proportion became exactly the same as in the former cases.
Welter’s bitter principlewas prepared by acting on silk with ten or twelve times its weight of nitric acid. The liquid, slightly coloured at first, acquired a deep yellow upon adding water. It was neutralized by carbonate of potash whilst hot, and left to cool, and the salt of potash thus obtained, decomposed by muriatic, nitric, or sulphuric acid. This acid, crystallized like that from indigo, formed the same salts, and was composed in the same manner. Silk furnishes much less of the substance than indigo. Dr. Liebeg has called this substancecarbazotic acid. The most important salts formed by it have the followingproperties:—
Carbazotate of Potash—crystallizes in long yellow quadrilateral needles, semi-transparent and very brilliant; it dissolves in 260 parts of water at 59° F., and in much less, boiling water: a saturated boiling solution becomes a yellow mass of needles, from which scarcely any fluid will run. Strong acids decompose it; yet when an alcoholic solution of carbazotic acid is added to a solution of nitre, crystallized carbazotate of potash, after some time, precipitates.—Alcohol does not dissolve it. When a little is gradually heated in a glass tube, it first fuses, and then suddenly explodes, breaking the tube to atoms; traces of charcoal are observed on the fragments. This salt precipitates a solution of the protonitrate of mercury, but not salts, containing the peroxide, or those of copper, lead, cobalt, iron, lime, baryta, strontia, or magnesia. The slight solubility of this salt supplies an easy method of testing and separating potash in a fluid. Even the potash in tincture of litmus may be discovered by it; for, on adding a few drops of carbazotic acid, dissolved in alcohol, to infusion of litmus, crystals of the salt gradually separated. The saturated solution of the salt at 50° F., is not troubled by muriate of platina. The salt contains no water of crystallization. It was analyzed by converting a portion of it into chloride of potassium by muriatic acid: its compositionis,—
Carbazotic acid83.79Potash16.21100.00
Carbazotate of Soda—crystallizes in fine silky yellow needles, having the general properties of the salt of potash, but soluble in from 20 to 24 parts of water, at 59° F.
Carbazotate of Ammoniaforms very long, flattened, brilliant,[p213]yellow crystals, very soluble in water. Heated carefully in a glass tube, it fuses, and is volatilized without decomposition; heated suddenly, it inflames without explosion, and leaves much carbonaceous residue.
Carbazotate of Baryta, obtained by heating carbonate of baryta, and carbazotic acid with water. It crystallizes in quadrangular prisms of a deep colour, and dissolves easily in water. When heated, it fuses, and is decomposed with very powerful explosion, producing a vivid yellow flame. The explosion is as powerful as that of fulminating silver; a solution of chloride of potassium to which carbazotate of baryta has been added, produces a precipitate of the potash salt, and not more than112per cent. of potash remains in solution. 100 parts of the crystallized saltcontain,—
Carbazotic acid69.16oxygen of the acid16Baryta21.60oxygen of the earth1Water9.24oxygen of the water8100.00
Carbazotate of Lime, obtained like the salt of baryta, forms flattened quadrangular prisms, very soluble in water, and detonating like the salt of potash.
Carbazotate of Magnesiaforms very long indistinct needles, of a clear yellow colour; is very soluble, and detonates violently.
Carbazotate of Copper, prepared by decomposing sulphate of copper by carbazotate of baryta: it crystallizes with difficulty, the crystals being of a fine green colour; it is deliquescent; when heated, it is decomposed without explosion, and even without inflammation.
Carbazotate of Silver.—Carbazotic acid readily dissolves oxide of silver, when heated with it and water; and the solution, gradually evaporated, yields starry groups of fine acicular crystals of the colour and lustre of gold; the salt dissolves readily in water; when heated to a certain degree, it does not detonate, but fuses like gunpowder.
Proto-Carbazotate of Mercury, obtained in small yellow triangular crystals, by mixing boiling solutions of the carbazotate of potash or soda, and proto-nitrate of mercury. It requires more than 1200 parts of water for its solution: for its perfect purification, it should be heated with a solution of chloride of potassium, the insoluble portion separated whilst the liquid is lost, and the peculiar salt allowed to deposit as the temperature falls. When heated, it behaves like the salt of silver.
All these salts detonate much more powerfully when heated in close vessels, than when heated in the air; and it was a curious thing to observe, that those with bases yielding oxygen most readily, were those which exploded with least force. By heating some of the salts previously mixed with chloride of potassium, &c., to retard the action, it appeared that no carbonic oxide, but only carbonic[p214]acid and azote were evolved during their decomposition by heat.
On the Bitter Principle from Aloes.—Upon distilling 8 parts of nitric acid from 1 part of the extract of aloes, and adding water to the remaining fluid, a resinous reddish yellow substance precipitated, which, by washing, became pulverulent—it was discovered by M. Braconnot. Upon evaporating the liquid separated from the precipitate, it gave large yellow rhomboidal crystals, not transparent, and but slightly soluble. These crystals, at first mistaken for a particular substance, were soon found to be a combination of oxalic acid with the bitter of aloes. The bitter substances of aloes dissolved in 800 parts of water, at 59° F., but in a smaller quantity of boiling water. This solution has a superb purple colour. Silk boiled in it acquired a very fine purple colour, on which neither soap nor acids effected any change, except nitric acid; this changed the colour to yellow, but it was restored simply by washing in water. All shades may be given to this colour by proper mordants. Wool is dyed black in a peculiarly beautiful manner, by the same process, and light has no influence on the colour. Leather acquires a purple colour; cotton, a rose colour; but the latter will not resist soap. Dr. Liebeg thinks that this is the only substance from which a permanent rose dye for silk may be expected.—Ann. de Chimie, xxxv. 72.
25.On the Existence of Crystals of Oxalate of Lime in Plants.—M. Raspail has read a memoir to the Academy of Sciences, to prove the analogy which exists in arrangement between the crystals of silica, which are found in sponges, and those of oxalate of lime occurring in the tissue of phanerogamous plants.
The latter crystals were observed, for the first time, by Rafn and Jurine, who regarded them as organs of which they knew not the use. They were then observed by M. de Candolle, who called themraphides, and gave a figure of them, which, however, is inaccurate. These crystals are really very regular tetraedrons. In many plants, asorchis,pandanus,ornithogalum,jacinthus,phytolacadecandria,mesembryanthemum deltoides, &c. they are very small, not being more than1200of a millimetre (.0002 of an inch) in width, and110(.004 of an inch) in length. But, in the tubercles of the Florence iris, they are as much as150(.0008 of an inch) in width, and13(.01312 of an inch) in length, so as to be easily capable of examination.—Bull. Univ.B. xi. 376.
26.Fallacy of Infusion of Litmus as a Test,byM. Magnus.—When pure water is heated for a sufficient time with infusion of litmus, reddened by an acid, it restores the blue colour. It is supposed that the heat gradually causes the free sulphuric acid, which had occasioned the reddening, to combine with the excess of alkali contained in the infusion, and thus to cause the restoration of the blue colour. Hence this preparation cannot be used to test the[p215]presence of ammonia in a solution, as water alone produces the effect anticipated from the alkali. The earthy salts contained in ordinary water also produce this effect.—Jour. de Pharmacie.
27.Tests for the Natural Colouring Matter of Wine.—M. A. Chevalier states,—i. That potash may be employed as a re-agent, to ascertain the natural colour of wines, which it changes from red to a bottle green, or brownish green—ii. That the change of colour produced by this substance upon wine is different for wine of different ages—iii. That no precipitation of the colouring matter takes place, the latter remaining dissolved by the potash—iv. That the acetate of lead should not be employed as a test of the colour of wines, because it is capable of producing various colours with wines of a natural colour only—v. That the same is the case with lime-water, with muriate of tin mixed with ammonia, and with subacetate of lead—vi. That ammonia may be employed for this purpose, the changes of colour which it produces not perceptibly varying—vii. That the same is the case with a solution of alum to which a certain quantity of potash has been added, and which may, therefore, be used for the purpose.—Annales de l’Industrie.
28.Test of the Presence of Opium.—Dr. Hare says he can detect opium in solution, when the quantity is not more than that given, by adding ten drops of laudanum to half a gallon of water. The following is the process:—a few drops of solution of acetate of lead is to be added to the solution containing the drug; after some time an observable quantity of meconiate of lead will fall down: from six to twelve hours may sometimes be required, and the precipitation is best effected in a conical glass vessel, for then, by gentle stirring now and then to liberate that which adheres to the side, the insoluble salt may be collected together at the bottom. About thirty drops of sulphuric acid are then to be poured on to the meconiate by means of a glass tube, after which as much of a solution of red sulphate of iron is to be added in the same manner. The sulphuric acid will liberate the meconic acid, and thus enable it to produce with the iron the appropriate colour, which demonstrates the presence of that acid, and consequently of opium.—Silliman’s Journal, xii. 290.
29.Denarcotized Laudanum.—Thinking it important to ascertain whether, by the removal of narcotine from opium, the unpleasant effects which, according to the opinions at present entertained upon that subject, are produced by that drug would be removed, Dr. Hare prepared some opium with ether, guided by Robiquet’s statement that narcotine was soluble in that fluid: the opium was shaved by rubbing it on the face of a jack-plane, and subjected four times successively to as much ether of the specific gravity 0.735 as would cover it, the operation being performed in a small Papin’s digester, at a temperature near the boiling point of ether, and each[p216]portion of the fluid being allowed twenty-four hours for its action. A crystalline deposition was soon observed in the ether which had been removed from the opium, and, allowing the stopper of the vessel to remain out, nearly the whole of the liquid evaporated in a few days, and left much coloured crystalline matter. This, Dr. Hare has no doubt, was narcotine in an impure state. The opium was afterwards subjected to as much alcohol as would have been required to convert it into laudanum, had it been in the ordinary state; and this being administered medicinally, was found to occasion none of those uneasy and unpleasant sensations which often follow the use of ordinary opium.—Silliman’s Journal, xii. 291.
30.Extraction of Morphia from Dry Poppy Heads, by M. Tilloy.—Make an aqueous extract of the heads, add alcohol to the extract, separate the alcoholic solution, and distil it; by this means the gummy matter is separated. An extract like syrup will be obtained by the distillation, which, being heated to make it thinner, and of the consistency of treacle, is to be again treated with alcohol; a separation of more gum, with much nitrate of potash, will be effected. The solution being withdrawn, is to be distilled, and the extract which will remain is to be acted upon by a sufficient quantity of water, and filtered, to separate the resinous matter present. The morphia may then be separated from this liquid, either by ammonia, carbonate of soda, or magnesia. Ammonia does not precipitate all the morphia; carbonate of soda precipitates a large quantity, but, it separates resinous matter also, which is found mingled with the morphia. Magnesia is preferable; but as the liquid contains much free acetic acid, it is expensive to employ the necessary quantity of pure magnesia: the liquid may, therefore, be partly saturated, whilst hot, by carbonate of magnesia, or even by carbonate of lime. A judgment, when no more must be added, must be formed from the effervescence; then pure magnesia is to be added, which will cause the liberation of ammonia; the whole is to be left for twenty-four hours to cool: being then filtered, the precipitate is to be washed, and, when dry, acted upon by alcohol. Operating in this manner, morphia may be obtained from all kinds of poppies.—Bull. Univ.E. viii. 10.
31.Preparation of Morphia.—Some curious experiments have been described to the Académie de Médecine, by M. Robinet, relative to the preparation of morphia. Having operated on the residue of opium by muriatic acid, and precipitated the morphia from the muriatic solution by lime, he wished to ascertain whether the mother liquor contained any morphia that had escaped precipitation. He, therefore, passed a current of carbonic acid gas through the solution, to precipitate the lime in excess: this precipitate being washed, dried, and acted upon by alcohol, was found mixed with a very large proportion of morphia, which could[p217]be thus separated. The washings of the precipitate being examined, were found free from morphia.
M. Henry observed, at the same time, that, from experiments made at La Pharmacie Centrale, it appeared that much more morphia was obtained in those processes in which lime had been used to precipitate the morphia, than in those in which magnesia had been used.—Bull. Univ.C. xi. 225.
32.Easy Method of obtaining Meconic Acid, by Dr. Hare.—If to an aqueous infusion of opium we add subacetate of lead, a copious precipitation of meconiate of lead ensues: this being collected by a filter, and exposed to sulphuretted hydrogen, meconic acid is liberated: the solution is of a reddish amber colour, and furnishes, by evaporation, crystals of the same hue. A very small quantity produces a very striking effect in reddening solution of peroxide of iron. Instead of sulphuretted hydrogen, sulphuric acid may be used to liberate the meconic acid: the presence of the former in excess does not seem to interfere with the power of reddening ferruginous solutions, but any excess of sulphuric acid may be removed by whitening, which is not acted upon sensibly by meconic acid; Yet, the acid procured in this way did not crystallize so handsomely, or with so much facility, as that obtained by sulphuretted hydrogen.
33.On a New Vegetable Acid.—This acid is crystallizable, but the forms have not as yet been determined: it is less soluble in cold water than tartaric acid; its aqueous solution precipitates lime water in white floculi, just like tartaric acid, but the precipitate, if dissolved in muriatic acid, re-appears on adding ammonia, whilst that produced by tartaric acid does not produce this effect. The new acid has a greater affinity for lime than muriatic or nitric acids, for it precipitates the muriate and nitrate of this earth in the manner of oxalic acid, but it differs from the latter in not precipitating a solution of sulphate of lime. With potash it forms an acid salt, slightly soluble in cold water: it precipitates acetate of lead, and the precipitate holds much water in combination: the tartrate of lead, on the contrary, is anhydrous. Notwithstanding these circumstances, the equivalent number of this acid is within a few thousandths of that of tartaric acid: when distilled, it is decomposed, and produces an acid yellow liquid like tartaric acid, leaving a light charcoal burning without residuum. M. Gay Lussac is engaged in developing the chemical history of this substance.—Bull. Univ.A. vii. 327.
34.Altheine, a new Vegetable Principle.—M. Bacon gives the following directions for the preparation of this substance, which he has discovered in theAlthea officinalis. An extract of the roots of the plant is to be made by means of cold water, and, when concentrated,[p218]acted upon by boiling alcohol: the latter will dissolve the acid malate of altheine, oil, &c.: the different alcoholic decoctions are to be put together and will throw down a crystalline deposite as they cool; the latter is to be separated and dissolved in water, and the solution, when filtered, is to be evaporated by a moderate heat, until like a syrup, and then set aside to crystallize. The crystals procured are to be washed with a small quantity of pure water, to separate the yellow matter from them, and then dried upon paper. These crystals appear, to the naked eye, like grains, needles, and feathers, but under the microscope present a hexaedral form. They are of a fine emerald green colour, transparent, brilliant, inodorous; unaltered in the air; they redden litmus paper, are soluble in water, and insoluble in alcohol. The aqueous solution of these crystals, acted upon by cold magnesia and filtered, then restores the colour of reddened litmus paper; renders syrup of violets green; and when evaporated furnishes the altheine free from malic acid. When thus pure, the substance crystallizes in regular hexaedral forms or in rhomboidal octoedrons; it affects litmus and violets as just described: it is transparent, of an emerald green colour, brilliant, inodorous, slightly sapid, unaltered by air, very soluble in water, not soluble in alcohol, soluble in acetic acid, with which it forms a crystalline salt.—Ann. de Chimie, xxxiv. 201.
35.Rheine, a new Substance from Rhubarb.—By acting upon one part of Chinese rhubarb with 8 parts of nitric acid, s. g. 1.32, at a moderate temperature, reducing the whole to the consistence of syrup, and then diffusing it through water, M. Vaudin obtained a precipitate which possessed peculiar characters, and to which he gave the name ofRheine. When dry, it is of an orange yellow colour, without any particular odour, and slightly bitter. It dissolves in water as well as in alcohol and ether: the solutions become yellow by acids, and rose red by alkalis. It burns nearly in the manner of amadou. Rhubarb acted upon by ether only gave a similar substance, a circumstance which proves that Rheine exists ready formed in rhubarb, and that it is not acted upon by nitric acid.—Ann. de Chimie, xxxiv. 192.
36.On Dragon’s Blood, and a new Substance which it contains,byM. Melandri.—Pure dragon’s blood is, according to M. Melandri, a scarce substance; the drops in which it occurs are rarely transparent, generally opaque, and with a rough fracture: its colour is blood red. Besides being soluble in alcohol it is entirely soluble in oil and also in hot water, though a large quantity of the latter fluid is required for the purpose. The aqueous solution is bitter, astringent, and of a fine purple colour; by cooling, it becomes milky and red. Gelatine does not alter its appearance; a proof that the substance contains no tannin. Sulphate of iron forms a pale reddish precipitate, so that no evidence of gallic acid is afforded.[p219]
Supposing that this substance might contain a principle analogous to that latterly observed by M. Pelletier in logwood, &c. a portion of it was dissolved in strong alcohol, the solution evaporated until very concentrated, and then poured into cold water, an agglomerated spongy substance was precipitated, which, after being washed with cold water and filtered, was triturated with water containing1100thof sulphuric acid, and exhibited traces of chemical action at a temperature of 22° (61°.6 F.) It then deposited a substance upon the sides of the vessel, and the liquid became yellow and very acid. The sediment, being carefully washed with water, was of a fine red colour, varying according to the state of aggregation; it had no taste or smell; was flexible between the fingers, and was quite fluid at 55° (131° F.). This substance, which the author has calledDracine, has some analogy with the vegeto-alkalis, although its affinity for acids is but slight. The sulphate may be obtained, he says, by adding sulphuric acid diluted with alcohol to an alcoholic solution ofdracine, precipitating the mixture by cold water, and then applying a little heat; the sulphate of dracine collects at the bottom, is to be washed with cold water until the latter no longer reddens litmus paper, and then dissolved in hot water. This solution becomes red by the smallest quantity of alkalis, and may be used as a very sensible test of their presence. Dracine is also a good test for acids, assuming a yellow colour with them. The small quantity of carbonate of lime in filtering paper may be detected by sulphate of dracine, the yellow solution instantly becoming red from its action, and thus showing its presence.—Bull. Univ.C. xi. p. 157.
37.Purification of Madder, by the Separation of its Yellow Colouring Matter.—The experiments ofMM. Kuhlman, Colin, and Robiquet36, have induced M. G. H. de Kurrer to publish the means which he has resorted to for the purification of madder, by the separation of the yellow colouring matter from it; and thus rendering it more fit to supply the various red, lilac, violet, and brown colours which are required upon wool, silk, cotton and linen. Three tubs or vessels are placed by the side of each other: in summer they may be in the open air under shelter, but in the winter should be placed in an airy cellar where the temperature may be retained at 18° or 20° R. (73° to 77° F.). The first is that in which the soaking and fermentation is to be effected: it should be 2 feet 8 inches deep, and 2 feet 6 inches in diameter, for from fifty to fifty-five pounds of madder. The second, or washing vessel, should be512feet deep, and 3 feet in diameter; it should have three wooden cocks fixed into it, the first 2 feet, the second 3 feet, and the third 4 feet from the bottom. The third tub is for deposition; its height should be412feet, and it should have a cock at112foot from the bottom.[p220]
On commencing the operation, 50 or 55 lb. of pulverised madder are to be put into the first vessel, water is to be added, and stirred into the mass until it stands112inch above the madder. The whole is then to be left until fermentation comes on and has formed a coat of madder at the surface; this usually takes place in 36 hours, and at latest in 48 hours, according to the temperature. The mass should now be transferred into the second vessel, which is then to be filled with water, and being left for two hours, the madder will fall to the bottom. The upper cock is then to be opened, after that the second, and then the third; and the water which runs from the two latter is to be put into the third vessel, that the rest of the madder may separate from it. The madder in the second vessel is then to be washed a second, third, or fourth time until the washing water is colourless. Thus purified, the madder may be used in the processes of dyeing, according to the known methods; but it is important in summer that it should be used immediately, that a new (the vinous) fermentation may be avoided. The madder deposited in the third vessel, when washed and deposited, may be used like the rest. The liquid first separated after the fermentation may be used in the preparation of hot indigo baths, &c. instead of madder.—Bull. Univ.P. vii. 352.
36See page 239 of the last volume.
36See page 239 of the last volume.
38.On Indigo and Indigogene, by M. Liebeg.—112part of pure indigo, 2 parts of proto-sulphate of iron,212parts of hydrate of lime, and from 50 to 60 parts of water, were digested together for 24 hours in a close vessel, which had previously been filled with hydrogen. The clear liquor over the sulphate of lime and oxide of iron, had a yellowish red colour, and was separated by a syphon filled with hydrogen, and mixed with diluted muriatic acid, containing some sulphite of ammonia dissolved; a dense white precipitate was formed, becoming blue in the air. This was gathered in a filter without contact of air, and washed with boiled water containing sulphite of ammonia in solution, and dried at 212°, in close vessels, through which a current of hydrogen was continually passed. The upper surface of the mass became of a blue colour, but the lower remained of a dull white.
This white substance was called Indigogene. It did not change colour in dry air, but under water became of a deep blue, which by drying, assumed a coppery appearance. The blue substance volatilized by heat without leaving any residue, forming purple vapours, which condensed, when cold, into crystals differing in nothing from sublimed indigo.Indigogenedissolves in alkalis without neutralizing them: it is also soluble in alcohol, but insoluble in water or acids.
A given quantity of this indigogene was acted upon by ammonia, and the weight of the undissolved blue portion ascertained, it appeared that the weight of the pure portion dissolved was 0.404 grammes (6.224 grains.) The solution was put into an inverted[p221]jar, over mercury, and oxygen gas gradually passed in until absorption ceased, and then the liquid containing the precipitated indigo was evaporated to dryness at 212°. The weight of the substance was increased to 0.047,i. e.11.5 per cent.
Not having obtained indigogeneperfectlypure, M. Liebeg did not attempt to analyze it for the ultimate composition. He remarks, that indigo is, perhaps, the only organic body from which one of its constituent parts may be taken without total decomposition; and which, by oxidation, passes to the state of an indifferent body, having much analogy with peroxides.—Ann. de Chimie, xxxv. 269.
39.On the mutual Action of Ethers, and other Substances.—From experiments made by M. Henry, he concludes that when metals easily oxidizable, or oxides which unite with acetic acid, are put into sulphuric ether, they produce larger or smaller quantities of acetates, probably, not by decomposing the sulphuric ether, but the acetic ether which is always mixed with it; and that it is in consequence of the saturation of the acetic acid set free from the ether by this decomposition, that sulphuric ether does not redden litmus paper when evaporated, whereas it acts differently when being slightly heated, the quantity of acetic ether contained in it is allowed to decompose by the action of the air.
Nitric and acetic ethers are described as being easily decomposed by the action of many bodies without the assistance of heat, if aided by time. Amongst the products of the action are the acids of the ethers, acetates, and alcohol which dissolves the salts formed.—Jour. de Chimie Méd.
40.Faraday’s Chemical Manipulation.—The kindness of a friend at Bristol has pointed out to me an error in the directions relative to alkalimetry, which I have given in the above work: this I am desirous of correcting, and, by permission of Mr. Brande, have the opportunity of doing so in theQuarterly Journal of Science.
The mistake, which arose from using the wrong specific gravity of two that were required in calculation, occurs in the paragraphs (599, 600,) but fortunately is prevented from occasioning any experimental error by the directions given in (602). The acid of specific gravity, 1.141, directed to be used, is too strong for the quantities marked upon the tube. The substitution of one of specific gravity 1.127, will correct the error, and may be obtained very nearly by mixing 19 parts, by weight, of strong oil of vitriol, with 81 parts of water.
The alterations required may be made in the volume with a pen, as for errors of the press, by reading “1.127” for “1.141” in lines 25 and 30 of page 276, and lines 2 and 13 of page 277; and “nineteen” for “one” in line 27, and “eighty-one” for “four” in line 28 of page 276.—M. F.[p222]