CHAPTER IV.

CHAPTER IV.PROGRESS OF ANALYTICAL CHEMISTRY.Analysis, or the art of determining the constituents of which every compound is composed, constitutes the essence of chemistry: it was therefore attempted as soon as the science put on any thing like a systematic form. At first, with very little success; but as knowledge became more and more general, chemists became more expert, and something like regular analysis began to appear. Thus, Brandt showed thatwhite vitriolis a compound of sulphuric acid and oxide of zinc; and Margraaf, thatseleniteorgypsumis a compound of sulphuric acid and lime. Dr. Black made analyses of several of the salts of magnesia, so far at least as to determine the nature of the constituents. For hardly any attempt was made in that early period of the art to determine the weight of the respective constituents. The first person who attempted to lay down rules for the regular analysis of minerals, and to reduce these rules to practice, was Bergman. This he did in his papers "De Docimasia Minerarum Humida," "De Terra Gemmarum," and "De Terra Tourmalini," published between the years 1777 and 1780.To analyze a mineral, or to separate it into its constituent parts, it is necessary in the first place, to be able to dissolve it in an acid. Bergman showed that most minerals become soluble in muriatic acidif they be reduced to a very fine powder, and then heated to redness, or fused with an alkaline carbonate. After obtaining a solution in this way he pointed out methods by which the different constituents may be separated one after another, and their relative quantities determined. The fusion with an alkaline carbonate required a strong red heat. An earthenware crucible could not be employed, because at a fusing temperature it would be corroded by the alkaline carbonate, and thus the mineral under analysis would be contaminated by the addition of a quantity of foreign matter. Bergman employed an iron crucible. This effectually prevented the addition of any earthy matter. But at a red heat the iron crucible itself is apt to be corroded by the action of the alkali, and thus the mineral under analysis becomes contaminated with a quantity of that metal. This iron might easily be separated again by known methods, and would therefore be of comparatively small consequence, provided we were sure that the mineral under examination contained no iron; but when that happens (and it is a very frequent occurrence), an error is occasioned which we cannot obviate. Klaproth made a vast improvement in the art of analysis, by substituting crucibles of fine silver for the iron crucibles of Bergman. The only difficulty attending their use was, that they were apt to melt unless great caution was used in heating them. Dr. Wollaston introduced crucibles of platinum about the beginning of the present century. It is from that period that we may date the commencement of accurate analyzing.Bergman's processes, as might have been expected, were rude and imperfect. It was Klaproth who first systematized chemical analysis and brought the art to such a state, that the processes followedcould be imitated by others with nearly the same results, thus offering a guarantee for the accuracy of the process.Martin Henry Klaproth, to whom chemistry lies under so many and such deep obligations, was born at Wernigerode, on the 1st of December, 1743. His father had the misfortune to lose his whole goods by a great fire, on the 30th of June, 1751, so that he was able to do little or nothing for the education of his children. Martin was the second of three brothers, the eldest of whom became a clergyman, and the youngest private secretary at war, and keeper of the archives of the cabinet of Berlin. Martin survived both his brothers. He procured such meagre instruction in the Latin language as the school of Wernigerode afforded, and he was obliged to procure his small school-fees by singing as one of the church choir. It was at first his intention to study theology; but the unmerited hard treatment which he met with at school so disinclined him to study, that he determined, in his sixteenth year, to learn the trade of an apothecary. Five years which he was forced to spend as an apprentice, and two as an assistant in the public laboratory in Quedlinburg, furnished him with but little scientific information, and gave him little else than a certain mechanical adroitness in the most common pharmaceutical preparations.He always regarded as the epoch of his scientific instruction, the two years which he spent in the public laboratory at Hanover, from Easter 1766, till the same time in 1768. It was there that he first met with some chemical books of merit, especially those of Spielman, and Cartheuser, in which a higher scientific spirit already breathed. He was now anxious to go to Berlin, of which he had formed a high idea from the works of Pott, Henkel, Rose,and Margraaf. An opportunity presenting itself about Easter, 1768, he was placed as assistant in the laboratory of Wendland, at the sign of the Golden Angel, in the Street of the Moors. Here he employed all the time which a conscientious discharge of the duties of his station left him, in completing his own scientific education. And as he considered a profounder acquaintance with the ancient languages, than he had been able to pick up at the school of Wernigerode, indispensable for a complete scientific education, he applied himself with great zeal to the study of the Greek and Latin languages, and was assisted in his studies by Mr. Poppelbourn, at that time a preacher.About Michaelmas, 1770, he went to Dantzig, as assistant in the public laboratory: but in March of the following year he returned to Berlin, as assistant in the office of the elder Valentine Rose, who was one of the most distinguished chemists of his day. But this connexion did not continue long; for Rose died in 1771. On his deathbed he requested Klaproth to undertake the superintendence of his office. Klaproth not only superintended this office for nine years with the most exemplary fidelity and conscientiousness, but undertook the education of the two sons of Rose, as if he had been their father. The younger died before reaching the age of manhood: the elder became his intimate friend, and the associate of all his scientific researches. For several years before the death of Rose (which happened in 1808) they wrought together, and Klaproth was seldom satisfied with the results of his experiments till they had been repeated by Rose.In the year 1780 Klaproth went through his trials for the office of apothecary with distinguished applause. His thesis, "On Phosphorus and distilled Waters," was printed in the Berlin Miscellanies for1782. Soon after this, Klaproth bought what had formerly been the Flemming laboratory in Spandau-street: and he married Sophia Christiana Lekman, with whom he lived till 1803 (when she died) in a happy state. They had three daughters and a son, who survived their parents. He continued in possession of this laboratory, in which he had arranged a small work-room of his own, till the year 1800, when he purchased the room of the Academical Chemists, in which he was enabled, at the expense of the academy, to furnish a better and more spacious apartment for his labours, for his mineralogical and chemical collection, and for his lectures.As soon as he had brought the first arrangements of his office to perfection—an office which, under his inspection and management, became the model of a laboratory, conducted upon the most excellent principles, and governed with the most conscientious integrity, he published in the various periodical works of Germany, such as "Crell's Chemical Annals," the "Writings of the Society for the promotion of Natural Knowledge," "Selle's Contributions to the Science of Nature and of Medicine," "Köhler's Journal," &c.; a multitude of papers which soon drew the attention of chemists; for example, his Essay on Copal—on the Elastic Stone—on Proust's Sel perlée—on the Green Lead Spar of Tschoppau—on the best Method of preparing Ammonia—on the Carbonate of Barytes—on the Wolfram of Cornwall—on Wood Tin—on the Violet Schorl—on the celebrated Aerial Gold—on Apatite, &c. All these papers, which secured him a high reputation as a chemist, appeared before 1788, when he was chosen an ordinary member of the physical class of the Royal Berlin Academy of Sciences. The Royal Academy of Arts had elected him a member a year earlier. From this time, every volume of theMemoirs of the Academy, and many other periodical works besides, contained numerous papers by this accomplished chemist; and there is not one of them which does not furnish us with a more exact knowledge of some one of the productions of nature or art. He has either corrected false representations, or extended views that were before partially known, or has revealed the composition and mixture of the parts of bodies, and has made us acquainted with a variety of new elementary substances. Amidst all these labours, it is difficult to say whether we should most admire the fortunate genius, which, in all cases, readily and easily divined the point where any thing of importance lay concealed; or the acuteness which enabled him to find the best means of accomplishing his object; or the unceasing labour and incomparable exactness with which he developed it; or the pure scientific feeling under which he acted, and which was removed at the utmost possible distance from every selfish, every avaricious, and every contentious purpose.In the year 1795 he began to collect his chemical works which lay scattered among so many periodical publications, and gave them to the world under the title of "Beitrage zur Chemischen Kenntniss der Mineralkörper" (Contributions to the Chemical Knowledge of Mineral Bodies). Of this work, which consists of six volumes, the last was published in 1815, about a year before the author's death. It contains no fewer than two hundred and seven treatises, the most valuable part of all that Klaproth had done for chemistry and mineralogy. It is a pity that the sale of this work did not permit the publication of a seventh volume, which would have included the rest of his papers, which he had not collected, and given us a good index to the whole work, which would have been of great importance to the practical chemist. There is, indeed, an index to the first five volumes; but it is meagre and defective, containing little else than the names of the substances on which his experiments were made.Besides his own works, the interest which he took in the labours of others deserves to be noticed. He superintended a new edition of Gren's Manual of Chemistry, remarkable not so much for what he added as for what he took away and corrected. The part which he took in Wolff's Chemical Dictionary was of great importance. The composition of every particular treatise was by Professor Wolff; but Klaproth read over every important article before it was printed, and assisted the editor on all occasions with the treasures of his experience and knowledge. Nor was he less useful to Fischer in his translation of Berthollet on Affinity and on Chemical Statics.These meritorious services, and the lustre which his character and discoveries conferred on his country were duly appreciated by his sovereign. In 1782 he had been made assessor in the Supreme College of Medicine and of Health, which then existed. At a more recent period he enjoyed the same rank in the Supreme Council of Medicine and of Health; and when this college was subverted, in 1810, he became a member of the medical deputation attached to the ministry of the interior. He was also a member of the perpetual court commission for medicines. His lectures, too, procured for him several municipal situations. As soon as the public became acquainted with his great chemical acquirements he was permitted to give yearly two private courses of lectures on chemistry; one for the officers of the royal artillery corps, the other for officers not connected with the army, who wished to accomplish themselves for some practical employment. Both of these lectures assumed afterwards a municipal character. The former led to his appointment as professor of the Artillery Academy instituted at Tempelhoff; and, after its dissolution, to his situation as professor in the Royal War School. The other lecture procured for him the professorship of chemistry in the Royal Mining Institute. On the establishment of the university, Klaproth's lectures became those of the university, and he himself was appointed ordinary professor of chemistry, and member of the academical senate. From 1797 to 1810 he was an active member of a small scientific society, which met yearly during a few weeks for the purpose of discussing the more recondite mysteries of the science. In the year 1811, the King of Prussia added to all his other honours the order of the Red Eagle of the third class.Klaproth spent the whole of a long life in the most active and conscientious discharge of all the duties of his station, and in an uninterrupted course of experimental investigations. He died at Berlin on the 1st of January, 1817, in the 70th year of his age.Among the remarkable traits in his character was his incorruptible regard for every thing that he believed to be true, honourable, and good; his pure love of science, with no reference whatever to any selfish, ambitious, and avaricious feeling; his rare modesty, undebased by the slightest vainglory or boasting. He was benevolently disposed towards all men, and never did a slighting or contemptuous word respecting any person fall from him. When forced to blame, he did it briefly, and without bitterness, for his blame always applied to actions, not to persons. His friendship was never the result of selfish calculation, but was founded on his opinion of the personal worth of the individual. Amidst all the unpleasant accidents of his life,which were far from few, he evinced the greatest firmness of mind. In his common behaviour he was pleasant and composed, and was indeed rather inclined to a joke. To all this may be added a true religious feeling, so uncommon among men of science of his day. His religion consisted not in words and forms, not in positive doctrines, nor in ecclesiastical observances, which, however, he believed to be necessary and honourable; but in a zealous and conscientious discharge of all his duties, not only of those which are imposed by the laws of men, but of those holy duties of love and charity, which no human law, but only that of God can command, and without which the most enlightened of men is but "as sounding brass, or a tinkling cymbal." He early showed this religious feeling by the honourable care which he bestowed on the education of the children of Valentine Rose. Nor did he show less care at an after-period towards his assistants and apprentices, to whom he refused no instruction, and in whose success he took the most active concern. He took a pleasure in every thing that was good and excellent, and felt a lively interest in every undertaking which he believed to be of general utility. He was equally removed from the superstition and infidelity of his age, and carried the principles of religion, not on his lips, but in the inmost feelings of his heart, from whence they emanated in actions which pervaded and ennobled his whole being and conduct.When we take a view of the benefits which Klaproth conferred upon chemistry, we must not look so much at the new elementary substances which he discovered, though they must not be forgotten, as at the new analytical methods which he introduced, the precision, and neatness, and order, and regularity with which his analyses were conducted,and the scrupulous fidelity with which every thing was faithfully stated as he found it.1. When a mineral is subjected to analysis, whatever care we take to collect all the constituents, and to weigh them without losing any portion whatever, it is generally found that the sum of the constituents obtained fall a little short of the weight of the mineral employed in the analysis. Thus, if we take 100 grains of any mineral, and analyze it, the weights of all the constituents obtained added together will rarely make up 100 grains, but generally somewhat less; perhaps only 99, or even 98 grains. But some cases occur, when the analysis of 100 grains of a mineral gives us constituents that weigh, when added together, more than 100 grains; perhaps 105, or, in some rare cases, as much as 110. It was the custom with Bergman, and other analysts of his time, to consider this deficiency or surplus as owing to errors in the analysis, and therefore to slur it over in the statement of the analysis, by bringing the weight of the constituents, by calculation, to amount exactly to 100 grains. Klaproth introduced the method of stating the results exactly as he got them. He gives the weight of mineral employed in all his analyses, and the weight of each constituent extracted. These weights, added together, generally show a loss, varying from two per cent. to a half per cent. This improvement may appear at first sight trifling; yet I am persuaded that to it we are indebted for most of the subsequent improvements introduced into analytical chemistry. If the loss sustained was too great, it was obvious either that the analysis had been badly performed, or that the mineral contains some constituent which had been overlooked, and not obtained. This laid him under the necessity of repeating the analysis; and if the loss continued, he naturally looked out forsome constituent which his analysis had not enabled him to obtain. It was in this way that he discovered the presence of potash in minerals; and Dr. Kennedy afterwards, by following out his processes, discovered soda as a constituent. It was in this way that water, phosphoric acid, arsenic acid, fluoric acid, boracic acid, &c., were also found to exist as constituents in various mineral bodies, which, but for the accurate mode of notation introduced by Klaproth, would have been overlooked and neglected.2. When Klaproth first began to analyze mineral bodies, he found it extremely difficult to bring them into a state capable of being dissolved in acids, without which an accurate analysis was impossible. Accordingly corundum, adamantine spar, and the zircon, or hyacinth, baffled his attempts for a considerable time, and induced him to consider the earth of corundum as of a peculiar nature. He obviated this difficulty by reducing the mineral to an extremely fine powder, and, after digesting it in caustic potash ley till all the water was dissipated, raising the temperature, and bringing the whole into a state of fusion. This fusion must be performed in a silver crucible. Corundum, and every other mineral which had remained insoluble after fusion with an alkaline carbonate, was found to yield to this new process. This was an improvement of considerable importance. All those stony minerals which contain a notable proportion of silica, in general become soluble after having been kept for some time in a state of ignition with twice their weight of carbonate of soda. At that temperature the silica of the mineral unites with the soda, and the carbonic acid is expelled. But when the quantity of silica is small, or when it is totally absent, heating with carbonate of soda does not answer so well. With such minerals, caustic potash or soda may be substituted with advantage; and there are some of them that cannot be analyzed without having recourse to that agent. I have succeeded in analyzing corundum and chrysoberyl, neither of which, when pure, contain any silica, by simply heating them in carbonate of soda; but the process does not succeed unless the minerals be reduced to an exceedingly minute powder.3. When Klaproth discovered potash in the idocrase, and in some other minerals, it became obvious that the old mode of rendering minerals soluble in acids by heating them with caustic potash, or an alkaline carbonate, could answer only for determining the quantity of silica, and of earths or oxides, which the mineral contained; but that it could not be used when the object was to determine its potash. This led him to substitutecarbonate of barytesinstead of potash or soda, or their carbonates. After having ascertained the quantity of silica, and of earths, and metallic oxides, which the mineral contained, his last process to determine the potash in it was conducted in this way: A portion of the mineral reduced to a fine powder was mixed with four or five times its weight of carbonate of barytes, and kept for some time (in a platinum crucible) in a red heat. By this process, the whole becomes soluble in muriatic acid. The muriatic acid solution is freed from silica, and afterwards from barytes, and all the earths and oxides which it contains, by means of carbonate of ammonia. The liquid, thus freed from every thing but the alkali, which is held in solution by the muriatic acid, and the ammonia, used as a precipitant, is evaporated to dryness, and the dry mass, cautiously heated in a platinum crucible till the ammoniacal salts are driven off. Nothing now remains but the potash, or soda, in combination with muriatic acid. The addition of muriate of platinum enables us to determine whether the alkalibe potash or soda: if it be potash, it occasions a yellow precipitate; but nothing falls if the alkali be soda.This method of analyzing minerals containing potash or soda is commonly ascribed to Rose. Fescher, in his Eloge of Klaproth, informs us that Klaproth said to him, more than once, that he was not quite sure whether he himself, or Rose, had the greatest share in bringing this method to a state of perfection. From this, I think it not unlikely that the original suggestion might have been owing to Rose, but that it was Klaproth who first put it to the test of experiment.The objection to this mode of analyzing is the high price of the carbonate of barytes. This is partly obviated by recovering the barytes in the state of carbonate; and this, in general, may be done, without much loss. Berthier has proposed to substitute oxide of lead for carbonate of barytes. It answers very well, is sufficiently cheap, and does not injure the crucible, provided the oxide of lead be mixed previously with a little nitrate of lead, to oxidize any fragments of metallic lead which it may happen to contain. Berthier's mode, therefore, in point of cheapness, is preferable to that of Klaproth. It is equally efficacious and equally accurate. There are some other processes which I myself prefer to either of these, because I find them equally easy, and still less expensive than either carbonate of barytes or oxide of lead. Davy's method with boracic acid is exceptionable, on account of the difficulty of separating the boracic acid completely again.4. The mode of separating iron and manganese from each other employed by Bergman was so defective, that no confidence whatever can be placed in his results. Even the methods suggested by Vauquelin, though better, are still defective. Butthe process followed by Klaproth is susceptible of very great precision. He has (we shall suppose) the mixture of iron and manganese to be separated from each other, in solution, in muriatic acid. The first step of the process is to convert the protoxide of iron (should it be in that state) into peroxide. For this purpose, a little nitric acid is added to the solution, and the whole heated for some time. The liquid is now to be rendered as neutral as possible; first, by driving off as much of the excess of acid as possible, by concentrating the liquid; and then by completing the neutralization, by adding very dilute ammonia, till no more can be added without occasioning a permanent precipitation. Into the liquid thus neutralized, succinate or benzoate of ammonia is dropped, as long as any precipitate appears. By this means, the whole peroxide of iron is thrown down in combination with succinic, or benzoic acid, while the whole manganese remains in solution. The liquid being filtered, to separate the benzoate of iron, the manganese may now (if nothing else be in the liquid) be thrown down by an alkaline carbonate; or, if the liquid contain magnesia, or any other earthy matter, by hydrosulphuret of ammonia, or chloride of lime.This process was the contrivance of Gehlen; but it was made known to the public by Klaproth, who ever after employed it in his analyses. Gehlen employed succinate of ammonia; but Hisinger afterwards showed that benzoate of ammonia might be substituted without any diminution of the accuracy of the separation. This last salt, being much cheaper than succinate of ammonia, answers better in this country. In Germany, the succinic acid is the cheaper of the two, and therefore the best.5. But it was not by new processes alone that Klaproth improved the mode of analysis, thoughthey were numerous and important; the improvements in the apparatus contributed not less essentially to the success of his experiments. When he had to do with very hard minerals, he employed a mortar of flint, or rather of agate. This mortar he, in the first place, analyzed, to determine exactly the nature of the constituents. He then weighed it. When a very hard body is pounded in such a mortar, a portion of the mortar is rubbed off, and mixed with the pounded mineral. What the quantity thus abraded was, he determined by weighing the mortar at the end of the process. The loss of weight gave the portion of the mortar abraded; and this portion must be mixed with the pounded mineral.When a hard stone is pounded in an agate mortar it is scarcely possible to avoid losing a little of it. The best method of proceeding is to mix the matter to be pounded (previously reduced to a coarse powder in a diamond mortar) with a little water. This both facilitates the trituration, and prevents any of the dust from flying away; and not more than a couple of grains of the mineral should be pounded at once. Still, owing to very obvious causes, a little of the mineral is sure to be lost during the pounding. When the process is finished, the whole powder is to be exposed to a red heat in a platinum crucible, and weighed. Supposing no loss, the weight should be equal to the quantity of the mineral pounded together with the portion abraded from the mortar. But almost always the weight will be found less than this. Suppose the original weight of the mineral before pounding wasa, and the quantity abraded from the mortar 1; then, if nothing were lost, the weight should bea+ 1; but we actually find it onlyb, a quantity less thana+ 1. To determine the weight of matter abraded from the mortar contained in this powder, we saya+ 1:b:: 1:x, thequantity from the mortar in our powder, andx=b/a+ 1. In performing the analysis, Klaproth attended to this quantity, which was silica, and subtracted it. Such minute attention may appear, at first sight superfluous; but it is not so. In analyzing sapphire, chrysoberyl, and some other very hard minerals, the quantity of silica abraded from the mortar sometimes amounts to five per cent. of the weight of the mineral; and if we were not to attend to the way in which this silica has been introduced into the powder, we should give an erroneous view of the constitution of the mineral under analysis. All the analyses of chrysoberyl hitherto published, give a considerable quantity of silica as a constituent of it. This silica, if really found by the analysts, must have been introduced from the mortar, for pure chrysoberyl contains no silica whatever, but is a definite compound of glucina, alumina, and oxide of iron.When Klaproth operated with fire, he always selected his vessels, whether of earthenware, glass, plumbago, iron, silver, or platinum, upon fixed principles; and showed more distinctly than chemists had previously been aware of, what an effect the vessel frequently has upon the result. He also prepared his reagents with great care, to ensure their purity; for obtaining several of which in their most perfect state, he invented several efficient methods. It is to the extreme care with which he selected his minerals for analysis, and to the purity of his reagents, and the fitness of his vessels for the objects in view, that the great accuracy of his analyses is to be, in a great measure, ascribed. He must also have possessed considerable dexterity in operating, for when he had in view to determine any particular point with accuracy, his results came, in general, exceedingly near the truth. I may notice, as an example of this, his analysis of sulphate of barytes, which was within about one-and-a-half per cent. of absolute correctness. When we consider the looseness of the data which chemists were then obliged to use, we cannot but be surprised at the smallness of the error. Berzelius, in possession of better data, and possessed of much dexterity, and a good apparatus, when he analyzed this salt many years afterwards, committed an error of a half per cent.Klaproth, during a very laborious life, wholly devoted to analytical chemistry, entirely altered the face of mineralogy. When he began his labours, chemists were not acquainted with the true composition of a single mineral. He analyzed above 200 species, and the greater number of them with so much accuracy, that his successors have, in most cases, confirmed the results which he obtained. The analyses least to be depended on, are of those minerals which contain both lime and magnesia; for his process for separating lime and magnesia from each other was not a good one; nor am I sure that he always succeeded completely in separating silica and magnesia from each other. This branch of analysis was first properly elucidated by Mr. Chenevix.6. Analytical chemistry was, in fact, systematized by Klaproth; and it is by studying his numerous and varied analyses, that modern chemists have learned this very essential, but somewhat difficult art; and have been able, by means of still more accurate data than he possessed, to bring it to a still greater degree of perfection. But it must not be forgotten, that Klaproth was in reality the creator of this art, and that on that account the greatest part of the credit due to the progress that has been made in it belongs to him.It would be invidious to point out the particularanalyses which are least exact; perhaps they ought rather to be ascribed to an unfortunate selection of specimens, than to any want of care or skill in the operator. But, during his analytical processes, he discovered a variety of new elementary substances which it may be proper to enumerate.In 1789 he examined a mineral calledpechblende, and found in it the oxide of a new metal, to which he gave the name ofuranium. He determined its characters, reduced it to the metallic state, and described its properties. It was afterwards examined by Richter, Bucholz, Arfvedson, and Berzelius.It was in the same year, 1789, that he published his analysis of the zircon; he showed it to be a compound of silica and a new earth, to which he gave the name of zirconia. He determined the properties of this new earth, and showed how it might be separated from other bodies and obtained in a state of purity. It has been since ascertained, that it is a metallic oxide, and the metallic basis of it is now distinguished by the name ofzirconium. In 1795 he showed that thehyacinthis composed of the same ingredients as the zircon; and that both, in fact, constitute only one species. This last analysis was repeated by Morveau, and has been often confirmed by modern analytical chemists.It was in 1795 that he analyzed what was at that time calledred schorl, and nowtitanite. He showed that it was the oxide of a new metallic body, to which he gave the name oftitanium. He described the properties of this new body, and pointed out its distinctive characters. It must not be omitted, however, that he did not succeed in obtaining oxide of titanium, ortitanic acid, as it is now called, in a state of purity. He was not able to separate a quantity of oxide of iron, with which it was united, and which gave it a reddish colour. It was firstobtained pure by H. Rose, the son of his friend and pupil, who took so considerable a part in his scientific investigations.Titanium, in the metallic state, was some years ago discovered by Dr. Wollaston, in the slag at the bottom of the iron furnace, at Merthyr Tydvil, in Wales. It is a yellow-coloured, brittle, but very hard metal, possessed of considerable beauty; but not yet applied to any useful purpose.In 1797 he examined the menachanite, a black sand from Cornwall, which had been subjected to a chemical analysis by Gregor, in 1791, who had extracted from it a new metallic substance, which Kirwan distinguished by the name ofmenachine. Klaproth ascertained that the new metal of Gregor was the very same as his own titanium, and that menachanite is a compound of titanic acid and oxide of iron. Thus Mr. Gregor had anticipated him in the discovery of titanium, though he was not aware of the circumstance till two years after his own experiments had been published.In the year 1793 he published a comparative set of experiments on the nature of carbonates of barytes and strontian; showing that their bases are two different earths, and not the same, as had been hitherto supposed in Germany. This was the first publication on strontian which appeared on the continent; and Klaproth seems to have been ignorant of what had been already done on it in Great Britain; at least, he takes no notice of it in his paper, and it was not his character to slur over the labours of other chemists, when they were known to him. Strontian was first mentioned as a peculiar earth by Dr. Crawford, in his paper on the medicinal properties of the muriate of barytes, published in 1790. The experiments on which he founded his opinions were made, he informs us, by Mr. Cruikshanks. Apaper on the same subject, by Dr. Hope, was read to the Royal Society of Edinburgh, in 1793; but they had been begun in 1791. In this paper Dr. Hope establishes the peculiar characters of strontian, and describes its salts with much precision.Klaproth had been again anticipated in his experiments on strontian; but he could not have become aware of this till afterwards. For his own experiments were given to the public before those of Dr. Hope.On the 25th of January, 1798, his paper on the gold ores of Transylvania was read at a meeting of the Academy of Sciences at Berlin. During his analysis of these ores, he detected a new white metal, to which he gave the name oftellurium. Of this metal he describes the properties, and points out its distinguishing characters.These ores had been examined by Muller, of Reichenstein, in the year 1782; and he had extracted from them a metal which he considered as differing from every other. Not putting full confidence in his own skill, he sent a specimen of his new metal to Bergman, requesting him to examine it and give his opinion respecting its nature. All that Bergman did was to show that the metallic body which he had got was not antimony, to which alone, of all known metals, it bore any resemblance. It might be inferred from this, that Muller's metal was new. But the subject was lost sight of, till the publication of Klaproth's experiments, in 1802, recalled it to the recollection of chemists. Indeed, Klaproth relates all that Muller had done, with the most perfect fairness.In the year 1804 he published the analysis of a red-coloured mineral, from Bastnäs in Sweden, which had been at one time confounded with tungsten; but which the Elhuyarts had shown to contain noneof that metal. Klaproth showed that it contained a new substance, as one of its constituents, which he considered as a new earth, and which he calledochroita, because it forms coloured salts with acids. Two years after, another analysis of the same mineral was published by Berzelius and Hisinger. They considered the new substance which the mineral contained as a metallic oxide, and to the unknown metallic base they gave the name ofcerium, which has been adopted by chemists in preference to Klaproth's name. The characters of oxide of cerium given by Berzelius and Hisinger, agree with those given by Klaproth to ochroita, in all the essential circumstances. Of course Klaproth must be considered as the discoverer of this new body. The distinction betweenearthandmetallic oxideis now known to be an imaginary one. All the substances formerly called earths are, in fact, metallic oxides.Besides these new substances, which he detected by his own labours, he repeated the analyses of others, and confirmed and extended the discoveries they had made. Thus, when Vauquelin discovered the new earthglucina, in the emerald and beryl, he repeated the analysis of these minerals, confirmed the discovery of Vauquelin, and gave a detailed account of the characters and properties of glucina. Gadolin had discovered another new earth in the mineral called gadolinite. This discovery was confirmed by the analysis of Ekeberg, who distinguished the new earth by the name of yttria. Klaproth immediately repeated the analysis of the gadolinite, confirmed the results of Ekeberg's analysis, and examined and described the properties ofyttria.When Dr. Kennedy discovered soda in basalt, Klaproth repeated the analysis of this mineral, and confirmed the results obtained by the Edinburgh analyst.But it would occupy too much room, if I were to enumerate every example of such conduct. Whoever will take the trouble to examine the different volumes of the Beitrage, will find several others not less striking or less useful.The service which Klaproth performed for mineralogy, in Germany, was performed equally in France by the important labours of M. Vauquelin. It was in France, in consequence of the exertions of Romé de Lisle, and the mathematical investigations of the Abbé Hauy, respecting the structure of crystals, which were gradually extended over the whole mineral kingdom, that the reform in mineralogy, which has now become in some measure general, originated. Hauy laid it down as a first principle, that every mineral species is composed of the same constituents united in the same proportion. He therefore considered it as an object of great importance, to procure an exact chemical analysis of every mineral species. Hitherto no exact analysis of minerals had been performed by French chemists; for Sage, who was the chemical mineralogist connected with the academy, satisfied himself with ascertaining the nature of the constituents of minerals, without determining their proportions. But Vauquelin soon displayed a knowledge of the mode of analysis, and a dexterity in the use of the apparatus which he employed, little less remarkable than that of Klaproth himself.Of Vauquelin's history I can give but a very imperfect account, as I have not yet had an opportunity of seeing any particulars of his life. He was a peasant-boy of Normandy, with whom Fourcroy accidentally met. He was pleased with his quickness and parts, and delighted with the honesty and integrity of his character. He took him with him to Paris, and gave him the superintendence of his laboratory. His chemical knowledge speedily became great, and his practice in experimenting gave him skill and dexterity: he seems to have performed all the analytical experiments which Fourcroy was in the habit of publishing. He speedily became known by his publications and discoveries. When the scientific institutions were restored or established, after the death of Robespierre, Vauquelin became a member of the Institute and chemist to the School of Mines. He was made also assay-master of the Mint. He was a professor of chemistry in Paris, and delivered, likewise, private lectures, and took in practical pupils into his laboratory. His laboratory was of considerable size, and he was in the habit of preparing both medicines and chemical reagents for sale. It was he chiefly that supplied the French chemists with phosphorus, &c., which cannot be conveniently prepared in a laboratory fitted up solely for scientific purposes.Vauquelin was by far the most industrious of all the French chemists, and has published more papers, consisting of mineral, vegetable, and animal analyses, than any other chemist without exception. When he had the charge of the laboratory of the School of Mines, Hauy was in the habit of giving him specimens of all the different minerals which he wished analyzed. The analyses were conducted with consummate skill, and we owe to him a great number of improvements in the methods of analysis. He is not entitled to the same credit as Klaproth, because he had the advantage of many analyses of Klaproth to serve him as a guide. But he had no model before him in France; and both the apparatus used by him, and the reagents which he employed, were of his own contrivance and preparation. I have sometimes suspected that his reagents were not always very pure; but I believe the true reason of the unsatisfactory nature of many of his analyses, is the bad choice made of the specimens selected for analysis. It is obvious from his papers, that Vauquelin was not a mineralogist; for he never attempts a description of the mineral which he subjects to analysis, satisfying himself with the specimen put into his hands by Hauy. Where that specimen was pure, as was the case with emerald and beryl, his analysis is very good; but when the specimen was impure or ill-chosen, then the result obtained could not convey a just notion of the constituents of the mineral. That Hauy would not be very difficult to please in his selection of specimens, I think myself entitled to infer from the specimens of minerals contained in his own cabinet, many of which were by no means well selected. I think, therefore, that the numerous analyses published by Vauquelin, in which the constituents assigned by him are not those, or, at least, not in the same proportions, as have been found by succeeding analysts, are to be ascribed, not to errors in the analysis, which, on the contrary, he always performed carefully, and with the requisite attention to precision, but to the bad selection of specimens put into his hand by Hauy, or those other individuals who furnished him with the specimens which he employed in his analyses. This circumstance is very much to be deplored; because it puts it out of our power to confide in an analysis of Vauquelin, till it has been repeated and confirmed by somebody else.Vauquelin not only improved the analytical methods, and reduced the art to a greater degree of simplicity and precision, but he discovered, likewise, new elementary bodies.The red lead ore of Siberia had early drawn the attention of chemists, on account of its beauty; and various attempts had been made to analyze it.Among others, Vauquelin tried his skill upon it, in 1789, in concert with M. Macquart, who had brought specimens of it from Siberia; but at that time he did not succeed in determining the nature of the acid with which the oxide of lead was combined in it. He examined it again in 1797, and now succeeded in separating an acid to which, from the beautiful coloured salts which it forms, he gave the name ofchromic. He determined the properties of this acid, and showed that its basis was a new metal to which he gave the name ofchromium. He succeeded in obtaining this metal in a separate state, and showed that its protoxide is an exceedingly beautiful green powder. This discovery has been of very great importance to different branches of manufacture in this country. The green oxide is used pretty extensively in painting green on porcelain. It constitutes an exceedingly beautiful green pigment, very permanent, and easily applied. The chromic acid, when combined with oxide of lead, forms either a yellow or an orange colour upon cotton cloth, both very fixed and exceedingly beautiful colours. In that way it is extensively used by the calico-printers; and the bichromate of potash is prepared, in a crystalline form, to a very considerable amount, both in Glasgow and Lancashire, and doubtless in other places.Vauquelin was requested by Hauy to analyze theberyl, a beautiful light-green mineral, crystallized in six-sided prisms, which occurs not unfrequently in granite rocks, especially in Siberia. He found it to consist chiefly of silica, united to alumina, and to another earthy body, very like alumina in many of its properties, but differing in others. To this new earth he gave the name ofglucina, on account of the sweet taste of its salts; a name not very appropriate, as alumina, yttria, lead, protoxide of chromium, and even protoxide of iron, form salts whichare distinguished by a sweet taste likewise. This discovery of glucina confers honour on Vauquelin, as it shows the care with which his analyses must have been conducted. A careless experimenter might easily have confoundedglucinawithalumina. Vauquelin's mode of distinguishing them was, to add sulphate of potash to their solution in sulphuric acid. If the earth in solution was alumina, crystals of alum would form in the course of a short time; but if the earth was glucina, no such crystals would make their appearance, alumina being the basis of alum, and not glucina. He showed, too, that glucina is easily dissolved in a solution of carbonate of ammonia, while alumina is not sensibly taken up by that solution.Vauquelin died in 1829, after having reached a good old age. His character was of the very best kind, and his conduct had always been most exemplary. He never interfered with politics, and steered his way through the bloody period of the revolution, uncontaminated by the vices or violence of any party, and respected and esteemed by every person.Mr. Chenevix deserves also to be mentioned as an improver of analytical chemistry. He was an Irish gentleman, who happened to be in Paris during the reign of terror, and was thrown into prison and put into the same apartment with several French chemists, whose whole conversation turned upon chemical subjects. He caught the infection, and, after getting out of prison, began to study the subject with much energy and success, and soon distinguished himself as an analytical chemist.His analysis of corundum and sapphire, and his observations on the affinity between magnesia and silica, are valuable, and led to considerable improvements in the method of analysis. His analyses ofthe arseniates of copper, though he demonstrated that several different species exist, are not so much to be depended on; because his method of separating and estimating the quantity of arsenic acid is not good. This difficult branch of analysis was not fully understood till afterwards.Chenevix was for several years a most laborious and meritorious chemical experimenter. It is much to be regretted that he should have been induced, in consequence of the mistake into which he fell respecting palladium, to abandon chemistry altogether. Palladium was originally made known to the public by an anonymous handbill which was circulated in London, announcing thatpalladium, or new silver, was on sale at Mrs. Forster's, and describing its properties. Chenevix, in consequence of the unusual way in which the discovery was announced, naturally considered it as an imposition on the public. He went to Mrs. Forster's, and purchased the whole palladium in her possession, and set about examining it, prepossessed with the idea that it was an alloy of some two known metals. After a laborious set of experiments, he considered that he had ascertained it to be a compound of platinum and mercury, or an amalgam of platinum made in a peculiar way, which he describes. This paper was read at a meeting of the Royal Society by Dr. Wollaston, who was secretary, and afterwards published in their Transactions. Soon after this publication, another anonymous handbill was circulated, offering a considerable price for every grain of palladiummadeby Mr. Chenevix's process, or by any other process whatever. No person appearing to claim the money thus offered, Dr. Wollaston, about a year after, in a paper read to the Royal Society, acknowledged himself to have been the discoverer of palladium, and related the process by which he had obtained itfrom the solution of crude platina in aqua regia. There could be no doubt after this, that palladium was a peculiar metal, and that Chenevix, in his experiments, had fallen into some mistake, probably by inadvertently employing a solution of palladium, instead of a solution of his amalgam of platinum; and thus giving the properties of the one solution to the other. It is very much to be regretted, that Dr. Wollaston allowed Mr. Chenevix's paper to be printed, without informing him, in the first place, of the true history of palladium: and I think that if he had been aware of the bad consequences that were to follow, and that it would ultimately occasion the loss of Mr. Chenevix to the science, he would have acted in a different manner. I have more than once conversed with Dr. Wollaston on the subject, and he assured me that he did every thing that he could do, short of betraying his secret, to prevent Mr. Chenevix from publishing his paper; that he had called upon, and assured him, that he himself had attempted his process without being able to succeed, and that he was satisfied that he had fallen into some mistake. As Mr. Chenevix still persisted in his conviction of the accuracy of his own experiments after repeated warnings, perhaps it is not very surprising that Dr. Wollaston allowed him to publish his paper, though; had he been aware of the consequences to their full extent, I am persuaded that he would not have done so. It comes to be a question whether, had Dr. Wollaston informed him of the whole secret, Mr. Chenevix would have been convinced.Another chemist, to whom the art of analyzing minerals lies under great obligations, is Dr. Frederick Stromeyer, professor of chemistry and pharmacy, in the University of Gottingen. He was originally a botanist, and only turned his attention to chemistry when he had the offer of the chemical chair at Gottingen. He then went to Paris, and studied practical chemistry for some years in Vauquelin's laboratory. He has devoted most of his attention to the analysis of minerals; and in the year 1821 published a volume of analyses under the title of "Untersuchungen über die Mischung der Mineralkörper und anderer damit verwandten Substanzen." It contains thirty analyses, which constitute perfect models of analytical sagacity and accuracy. After Klaproth's Beitrage, no book can be named more highly deserving the study of the analytical chemist than Stromeyer's Untersuchungen.The first paper in this work contains the analysis of arragonite. Chemists had not been able to discover any difference in the chemical constitution of arragonite and calcareous spar, both being compounds of

PROGRESS OF ANALYTICAL CHEMISTRY.

Analysis, or the art of determining the constituents of which every compound is composed, constitutes the essence of chemistry: it was therefore attempted as soon as the science put on any thing like a systematic form. At first, with very little success; but as knowledge became more and more general, chemists became more expert, and something like regular analysis began to appear. Thus, Brandt showed thatwhite vitriolis a compound of sulphuric acid and oxide of zinc; and Margraaf, thatseleniteorgypsumis a compound of sulphuric acid and lime. Dr. Black made analyses of several of the salts of magnesia, so far at least as to determine the nature of the constituents. For hardly any attempt was made in that early period of the art to determine the weight of the respective constituents. The first person who attempted to lay down rules for the regular analysis of minerals, and to reduce these rules to practice, was Bergman. This he did in his papers "De Docimasia Minerarum Humida," "De Terra Gemmarum," and "De Terra Tourmalini," published between the years 1777 and 1780.

To analyze a mineral, or to separate it into its constituent parts, it is necessary in the first place, to be able to dissolve it in an acid. Bergman showed that most minerals become soluble in muriatic acidif they be reduced to a very fine powder, and then heated to redness, or fused with an alkaline carbonate. After obtaining a solution in this way he pointed out methods by which the different constituents may be separated one after another, and their relative quantities determined. The fusion with an alkaline carbonate required a strong red heat. An earthenware crucible could not be employed, because at a fusing temperature it would be corroded by the alkaline carbonate, and thus the mineral under analysis would be contaminated by the addition of a quantity of foreign matter. Bergman employed an iron crucible. This effectually prevented the addition of any earthy matter. But at a red heat the iron crucible itself is apt to be corroded by the action of the alkali, and thus the mineral under analysis becomes contaminated with a quantity of that metal. This iron might easily be separated again by known methods, and would therefore be of comparatively small consequence, provided we were sure that the mineral under examination contained no iron; but when that happens (and it is a very frequent occurrence), an error is occasioned which we cannot obviate. Klaproth made a vast improvement in the art of analysis, by substituting crucibles of fine silver for the iron crucibles of Bergman. The only difficulty attending their use was, that they were apt to melt unless great caution was used in heating them. Dr. Wollaston introduced crucibles of platinum about the beginning of the present century. It is from that period that we may date the commencement of accurate analyzing.

Bergman's processes, as might have been expected, were rude and imperfect. It was Klaproth who first systematized chemical analysis and brought the art to such a state, that the processes followedcould be imitated by others with nearly the same results, thus offering a guarantee for the accuracy of the process.

Martin Henry Klaproth, to whom chemistry lies under so many and such deep obligations, was born at Wernigerode, on the 1st of December, 1743. His father had the misfortune to lose his whole goods by a great fire, on the 30th of June, 1751, so that he was able to do little or nothing for the education of his children. Martin was the second of three brothers, the eldest of whom became a clergyman, and the youngest private secretary at war, and keeper of the archives of the cabinet of Berlin. Martin survived both his brothers. He procured such meagre instruction in the Latin language as the school of Wernigerode afforded, and he was obliged to procure his small school-fees by singing as one of the church choir. It was at first his intention to study theology; but the unmerited hard treatment which he met with at school so disinclined him to study, that he determined, in his sixteenth year, to learn the trade of an apothecary. Five years which he was forced to spend as an apprentice, and two as an assistant in the public laboratory in Quedlinburg, furnished him with but little scientific information, and gave him little else than a certain mechanical adroitness in the most common pharmaceutical preparations.

He always regarded as the epoch of his scientific instruction, the two years which he spent in the public laboratory at Hanover, from Easter 1766, till the same time in 1768. It was there that he first met with some chemical books of merit, especially those of Spielman, and Cartheuser, in which a higher scientific spirit already breathed. He was now anxious to go to Berlin, of which he had formed a high idea from the works of Pott, Henkel, Rose,and Margraaf. An opportunity presenting itself about Easter, 1768, he was placed as assistant in the laboratory of Wendland, at the sign of the Golden Angel, in the Street of the Moors. Here he employed all the time which a conscientious discharge of the duties of his station left him, in completing his own scientific education. And as he considered a profounder acquaintance with the ancient languages, than he had been able to pick up at the school of Wernigerode, indispensable for a complete scientific education, he applied himself with great zeal to the study of the Greek and Latin languages, and was assisted in his studies by Mr. Poppelbourn, at that time a preacher.

About Michaelmas, 1770, he went to Dantzig, as assistant in the public laboratory: but in March of the following year he returned to Berlin, as assistant in the office of the elder Valentine Rose, who was one of the most distinguished chemists of his day. But this connexion did not continue long; for Rose died in 1771. On his deathbed he requested Klaproth to undertake the superintendence of his office. Klaproth not only superintended this office for nine years with the most exemplary fidelity and conscientiousness, but undertook the education of the two sons of Rose, as if he had been their father. The younger died before reaching the age of manhood: the elder became his intimate friend, and the associate of all his scientific researches. For several years before the death of Rose (which happened in 1808) they wrought together, and Klaproth was seldom satisfied with the results of his experiments till they had been repeated by Rose.

In the year 1780 Klaproth went through his trials for the office of apothecary with distinguished applause. His thesis, "On Phosphorus and distilled Waters," was printed in the Berlin Miscellanies for1782. Soon after this, Klaproth bought what had formerly been the Flemming laboratory in Spandau-street: and he married Sophia Christiana Lekman, with whom he lived till 1803 (when she died) in a happy state. They had three daughters and a son, who survived their parents. He continued in possession of this laboratory, in which he had arranged a small work-room of his own, till the year 1800, when he purchased the room of the Academical Chemists, in which he was enabled, at the expense of the academy, to furnish a better and more spacious apartment for his labours, for his mineralogical and chemical collection, and for his lectures.

As soon as he had brought the first arrangements of his office to perfection—an office which, under his inspection and management, became the model of a laboratory, conducted upon the most excellent principles, and governed with the most conscientious integrity, he published in the various periodical works of Germany, such as "Crell's Chemical Annals," the "Writings of the Society for the promotion of Natural Knowledge," "Selle's Contributions to the Science of Nature and of Medicine," "Köhler's Journal," &c.; a multitude of papers which soon drew the attention of chemists; for example, his Essay on Copal—on the Elastic Stone—on Proust's Sel perlée—on the Green Lead Spar of Tschoppau—on the best Method of preparing Ammonia—on the Carbonate of Barytes—on the Wolfram of Cornwall—on Wood Tin—on the Violet Schorl—on the celebrated Aerial Gold—on Apatite, &c. All these papers, which secured him a high reputation as a chemist, appeared before 1788, when he was chosen an ordinary member of the physical class of the Royal Berlin Academy of Sciences. The Royal Academy of Arts had elected him a member a year earlier. From this time, every volume of theMemoirs of the Academy, and many other periodical works besides, contained numerous papers by this accomplished chemist; and there is not one of them which does not furnish us with a more exact knowledge of some one of the productions of nature or art. He has either corrected false representations, or extended views that were before partially known, or has revealed the composition and mixture of the parts of bodies, and has made us acquainted with a variety of new elementary substances. Amidst all these labours, it is difficult to say whether we should most admire the fortunate genius, which, in all cases, readily and easily divined the point where any thing of importance lay concealed; or the acuteness which enabled him to find the best means of accomplishing his object; or the unceasing labour and incomparable exactness with which he developed it; or the pure scientific feeling under which he acted, and which was removed at the utmost possible distance from every selfish, every avaricious, and every contentious purpose.

In the year 1795 he began to collect his chemical works which lay scattered among so many periodical publications, and gave them to the world under the title of "Beitrage zur Chemischen Kenntniss der Mineralkörper" (Contributions to the Chemical Knowledge of Mineral Bodies). Of this work, which consists of six volumes, the last was published in 1815, about a year before the author's death. It contains no fewer than two hundred and seven treatises, the most valuable part of all that Klaproth had done for chemistry and mineralogy. It is a pity that the sale of this work did not permit the publication of a seventh volume, which would have included the rest of his papers, which he had not collected, and given us a good index to the whole work, which would have been of great importance to the practical chemist. There is, indeed, an index to the first five volumes; but it is meagre and defective, containing little else than the names of the substances on which his experiments were made.

Besides his own works, the interest which he took in the labours of others deserves to be noticed. He superintended a new edition of Gren's Manual of Chemistry, remarkable not so much for what he added as for what he took away and corrected. The part which he took in Wolff's Chemical Dictionary was of great importance. The composition of every particular treatise was by Professor Wolff; but Klaproth read over every important article before it was printed, and assisted the editor on all occasions with the treasures of his experience and knowledge. Nor was he less useful to Fischer in his translation of Berthollet on Affinity and on Chemical Statics.

These meritorious services, and the lustre which his character and discoveries conferred on his country were duly appreciated by his sovereign. In 1782 he had been made assessor in the Supreme College of Medicine and of Health, which then existed. At a more recent period he enjoyed the same rank in the Supreme Council of Medicine and of Health; and when this college was subverted, in 1810, he became a member of the medical deputation attached to the ministry of the interior. He was also a member of the perpetual court commission for medicines. His lectures, too, procured for him several municipal situations. As soon as the public became acquainted with his great chemical acquirements he was permitted to give yearly two private courses of lectures on chemistry; one for the officers of the royal artillery corps, the other for officers not connected with the army, who wished to accomplish themselves for some practical employment. Both of these lectures assumed afterwards a municipal character. The former led to his appointment as professor of the Artillery Academy instituted at Tempelhoff; and, after its dissolution, to his situation as professor in the Royal War School. The other lecture procured for him the professorship of chemistry in the Royal Mining Institute. On the establishment of the university, Klaproth's lectures became those of the university, and he himself was appointed ordinary professor of chemistry, and member of the academical senate. From 1797 to 1810 he was an active member of a small scientific society, which met yearly during a few weeks for the purpose of discussing the more recondite mysteries of the science. In the year 1811, the King of Prussia added to all his other honours the order of the Red Eagle of the third class.

Klaproth spent the whole of a long life in the most active and conscientious discharge of all the duties of his station, and in an uninterrupted course of experimental investigations. He died at Berlin on the 1st of January, 1817, in the 70th year of his age.

Among the remarkable traits in his character was his incorruptible regard for every thing that he believed to be true, honourable, and good; his pure love of science, with no reference whatever to any selfish, ambitious, and avaricious feeling; his rare modesty, undebased by the slightest vainglory or boasting. He was benevolently disposed towards all men, and never did a slighting or contemptuous word respecting any person fall from him. When forced to blame, he did it briefly, and without bitterness, for his blame always applied to actions, not to persons. His friendship was never the result of selfish calculation, but was founded on his opinion of the personal worth of the individual. Amidst all the unpleasant accidents of his life,which were far from few, he evinced the greatest firmness of mind. In his common behaviour he was pleasant and composed, and was indeed rather inclined to a joke. To all this may be added a true religious feeling, so uncommon among men of science of his day. His religion consisted not in words and forms, not in positive doctrines, nor in ecclesiastical observances, which, however, he believed to be necessary and honourable; but in a zealous and conscientious discharge of all his duties, not only of those which are imposed by the laws of men, but of those holy duties of love and charity, which no human law, but only that of God can command, and without which the most enlightened of men is but "as sounding brass, or a tinkling cymbal." He early showed this religious feeling by the honourable care which he bestowed on the education of the children of Valentine Rose. Nor did he show less care at an after-period towards his assistants and apprentices, to whom he refused no instruction, and in whose success he took the most active concern. He took a pleasure in every thing that was good and excellent, and felt a lively interest in every undertaking which he believed to be of general utility. He was equally removed from the superstition and infidelity of his age, and carried the principles of religion, not on his lips, but in the inmost feelings of his heart, from whence they emanated in actions which pervaded and ennobled his whole being and conduct.

When we take a view of the benefits which Klaproth conferred upon chemistry, we must not look so much at the new elementary substances which he discovered, though they must not be forgotten, as at the new analytical methods which he introduced, the precision, and neatness, and order, and regularity with which his analyses were conducted,and the scrupulous fidelity with which every thing was faithfully stated as he found it.

1. When a mineral is subjected to analysis, whatever care we take to collect all the constituents, and to weigh them without losing any portion whatever, it is generally found that the sum of the constituents obtained fall a little short of the weight of the mineral employed in the analysis. Thus, if we take 100 grains of any mineral, and analyze it, the weights of all the constituents obtained added together will rarely make up 100 grains, but generally somewhat less; perhaps only 99, or even 98 grains. But some cases occur, when the analysis of 100 grains of a mineral gives us constituents that weigh, when added together, more than 100 grains; perhaps 105, or, in some rare cases, as much as 110. It was the custom with Bergman, and other analysts of his time, to consider this deficiency or surplus as owing to errors in the analysis, and therefore to slur it over in the statement of the analysis, by bringing the weight of the constituents, by calculation, to amount exactly to 100 grains. Klaproth introduced the method of stating the results exactly as he got them. He gives the weight of mineral employed in all his analyses, and the weight of each constituent extracted. These weights, added together, generally show a loss, varying from two per cent. to a half per cent. This improvement may appear at first sight trifling; yet I am persuaded that to it we are indebted for most of the subsequent improvements introduced into analytical chemistry. If the loss sustained was too great, it was obvious either that the analysis had been badly performed, or that the mineral contains some constituent which had been overlooked, and not obtained. This laid him under the necessity of repeating the analysis; and if the loss continued, he naturally looked out forsome constituent which his analysis had not enabled him to obtain. It was in this way that he discovered the presence of potash in minerals; and Dr. Kennedy afterwards, by following out his processes, discovered soda as a constituent. It was in this way that water, phosphoric acid, arsenic acid, fluoric acid, boracic acid, &c., were also found to exist as constituents in various mineral bodies, which, but for the accurate mode of notation introduced by Klaproth, would have been overlooked and neglected.

2. When Klaproth first began to analyze mineral bodies, he found it extremely difficult to bring them into a state capable of being dissolved in acids, without which an accurate analysis was impossible. Accordingly corundum, adamantine spar, and the zircon, or hyacinth, baffled his attempts for a considerable time, and induced him to consider the earth of corundum as of a peculiar nature. He obviated this difficulty by reducing the mineral to an extremely fine powder, and, after digesting it in caustic potash ley till all the water was dissipated, raising the temperature, and bringing the whole into a state of fusion. This fusion must be performed in a silver crucible. Corundum, and every other mineral which had remained insoluble after fusion with an alkaline carbonate, was found to yield to this new process. This was an improvement of considerable importance. All those stony minerals which contain a notable proportion of silica, in general become soluble after having been kept for some time in a state of ignition with twice their weight of carbonate of soda. At that temperature the silica of the mineral unites with the soda, and the carbonic acid is expelled. But when the quantity of silica is small, or when it is totally absent, heating with carbonate of soda does not answer so well. With such minerals, caustic potash or soda may be substituted with advantage; and there are some of them that cannot be analyzed without having recourse to that agent. I have succeeded in analyzing corundum and chrysoberyl, neither of which, when pure, contain any silica, by simply heating them in carbonate of soda; but the process does not succeed unless the minerals be reduced to an exceedingly minute powder.

3. When Klaproth discovered potash in the idocrase, and in some other minerals, it became obvious that the old mode of rendering minerals soluble in acids by heating them with caustic potash, or an alkaline carbonate, could answer only for determining the quantity of silica, and of earths or oxides, which the mineral contained; but that it could not be used when the object was to determine its potash. This led him to substitutecarbonate of barytesinstead of potash or soda, or their carbonates. After having ascertained the quantity of silica, and of earths, and metallic oxides, which the mineral contained, his last process to determine the potash in it was conducted in this way: A portion of the mineral reduced to a fine powder was mixed with four or five times its weight of carbonate of barytes, and kept for some time (in a platinum crucible) in a red heat. By this process, the whole becomes soluble in muriatic acid. The muriatic acid solution is freed from silica, and afterwards from barytes, and all the earths and oxides which it contains, by means of carbonate of ammonia. The liquid, thus freed from every thing but the alkali, which is held in solution by the muriatic acid, and the ammonia, used as a precipitant, is evaporated to dryness, and the dry mass, cautiously heated in a platinum crucible till the ammoniacal salts are driven off. Nothing now remains but the potash, or soda, in combination with muriatic acid. The addition of muriate of platinum enables us to determine whether the alkalibe potash or soda: if it be potash, it occasions a yellow precipitate; but nothing falls if the alkali be soda.

This method of analyzing minerals containing potash or soda is commonly ascribed to Rose. Fescher, in his Eloge of Klaproth, informs us that Klaproth said to him, more than once, that he was not quite sure whether he himself, or Rose, had the greatest share in bringing this method to a state of perfection. From this, I think it not unlikely that the original suggestion might have been owing to Rose, but that it was Klaproth who first put it to the test of experiment.

The objection to this mode of analyzing is the high price of the carbonate of barytes. This is partly obviated by recovering the barytes in the state of carbonate; and this, in general, may be done, without much loss. Berthier has proposed to substitute oxide of lead for carbonate of barytes. It answers very well, is sufficiently cheap, and does not injure the crucible, provided the oxide of lead be mixed previously with a little nitrate of lead, to oxidize any fragments of metallic lead which it may happen to contain. Berthier's mode, therefore, in point of cheapness, is preferable to that of Klaproth. It is equally efficacious and equally accurate. There are some other processes which I myself prefer to either of these, because I find them equally easy, and still less expensive than either carbonate of barytes or oxide of lead. Davy's method with boracic acid is exceptionable, on account of the difficulty of separating the boracic acid completely again.

4. The mode of separating iron and manganese from each other employed by Bergman was so defective, that no confidence whatever can be placed in his results. Even the methods suggested by Vauquelin, though better, are still defective. Butthe process followed by Klaproth is susceptible of very great precision. He has (we shall suppose) the mixture of iron and manganese to be separated from each other, in solution, in muriatic acid. The first step of the process is to convert the protoxide of iron (should it be in that state) into peroxide. For this purpose, a little nitric acid is added to the solution, and the whole heated for some time. The liquid is now to be rendered as neutral as possible; first, by driving off as much of the excess of acid as possible, by concentrating the liquid; and then by completing the neutralization, by adding very dilute ammonia, till no more can be added without occasioning a permanent precipitation. Into the liquid thus neutralized, succinate or benzoate of ammonia is dropped, as long as any precipitate appears. By this means, the whole peroxide of iron is thrown down in combination with succinic, or benzoic acid, while the whole manganese remains in solution. The liquid being filtered, to separate the benzoate of iron, the manganese may now (if nothing else be in the liquid) be thrown down by an alkaline carbonate; or, if the liquid contain magnesia, or any other earthy matter, by hydrosulphuret of ammonia, or chloride of lime.

This process was the contrivance of Gehlen; but it was made known to the public by Klaproth, who ever after employed it in his analyses. Gehlen employed succinate of ammonia; but Hisinger afterwards showed that benzoate of ammonia might be substituted without any diminution of the accuracy of the separation. This last salt, being much cheaper than succinate of ammonia, answers better in this country. In Germany, the succinic acid is the cheaper of the two, and therefore the best.

5. But it was not by new processes alone that Klaproth improved the mode of analysis, thoughthey were numerous and important; the improvements in the apparatus contributed not less essentially to the success of his experiments. When he had to do with very hard minerals, he employed a mortar of flint, or rather of agate. This mortar he, in the first place, analyzed, to determine exactly the nature of the constituents. He then weighed it. When a very hard body is pounded in such a mortar, a portion of the mortar is rubbed off, and mixed with the pounded mineral. What the quantity thus abraded was, he determined by weighing the mortar at the end of the process. The loss of weight gave the portion of the mortar abraded; and this portion must be mixed with the pounded mineral.

When a hard stone is pounded in an agate mortar it is scarcely possible to avoid losing a little of it. The best method of proceeding is to mix the matter to be pounded (previously reduced to a coarse powder in a diamond mortar) with a little water. This both facilitates the trituration, and prevents any of the dust from flying away; and not more than a couple of grains of the mineral should be pounded at once. Still, owing to very obvious causes, a little of the mineral is sure to be lost during the pounding. When the process is finished, the whole powder is to be exposed to a red heat in a platinum crucible, and weighed. Supposing no loss, the weight should be equal to the quantity of the mineral pounded together with the portion abraded from the mortar. But almost always the weight will be found less than this. Suppose the original weight of the mineral before pounding wasa, and the quantity abraded from the mortar 1; then, if nothing were lost, the weight should bea+ 1; but we actually find it onlyb, a quantity less thana+ 1. To determine the weight of matter abraded from the mortar contained in this powder, we saya+ 1:b:: 1:x, thequantity from the mortar in our powder, andx=b/a+ 1. In performing the analysis, Klaproth attended to this quantity, which was silica, and subtracted it. Such minute attention may appear, at first sight superfluous; but it is not so. In analyzing sapphire, chrysoberyl, and some other very hard minerals, the quantity of silica abraded from the mortar sometimes amounts to five per cent. of the weight of the mineral; and if we were not to attend to the way in which this silica has been introduced into the powder, we should give an erroneous view of the constitution of the mineral under analysis. All the analyses of chrysoberyl hitherto published, give a considerable quantity of silica as a constituent of it. This silica, if really found by the analysts, must have been introduced from the mortar, for pure chrysoberyl contains no silica whatever, but is a definite compound of glucina, alumina, and oxide of iron.

When Klaproth operated with fire, he always selected his vessels, whether of earthenware, glass, plumbago, iron, silver, or platinum, upon fixed principles; and showed more distinctly than chemists had previously been aware of, what an effect the vessel frequently has upon the result. He also prepared his reagents with great care, to ensure their purity; for obtaining several of which in their most perfect state, he invented several efficient methods. It is to the extreme care with which he selected his minerals for analysis, and to the purity of his reagents, and the fitness of his vessels for the objects in view, that the great accuracy of his analyses is to be, in a great measure, ascribed. He must also have possessed considerable dexterity in operating, for when he had in view to determine any particular point with accuracy, his results came, in general, exceedingly near the truth. I may notice, as an example of this, his analysis of sulphate of barytes, which was within about one-and-a-half per cent. of absolute correctness. When we consider the looseness of the data which chemists were then obliged to use, we cannot but be surprised at the smallness of the error. Berzelius, in possession of better data, and possessed of much dexterity, and a good apparatus, when he analyzed this salt many years afterwards, committed an error of a half per cent.

Klaproth, during a very laborious life, wholly devoted to analytical chemistry, entirely altered the face of mineralogy. When he began his labours, chemists were not acquainted with the true composition of a single mineral. He analyzed above 200 species, and the greater number of them with so much accuracy, that his successors have, in most cases, confirmed the results which he obtained. The analyses least to be depended on, are of those minerals which contain both lime and magnesia; for his process for separating lime and magnesia from each other was not a good one; nor am I sure that he always succeeded completely in separating silica and magnesia from each other. This branch of analysis was first properly elucidated by Mr. Chenevix.

6. Analytical chemistry was, in fact, systematized by Klaproth; and it is by studying his numerous and varied analyses, that modern chemists have learned this very essential, but somewhat difficult art; and have been able, by means of still more accurate data than he possessed, to bring it to a still greater degree of perfection. But it must not be forgotten, that Klaproth was in reality the creator of this art, and that on that account the greatest part of the credit due to the progress that has been made in it belongs to him.

It would be invidious to point out the particularanalyses which are least exact; perhaps they ought rather to be ascribed to an unfortunate selection of specimens, than to any want of care or skill in the operator. But, during his analytical processes, he discovered a variety of new elementary substances which it may be proper to enumerate.

In 1789 he examined a mineral calledpechblende, and found in it the oxide of a new metal, to which he gave the name ofuranium. He determined its characters, reduced it to the metallic state, and described its properties. It was afterwards examined by Richter, Bucholz, Arfvedson, and Berzelius.

It was in the same year, 1789, that he published his analysis of the zircon; he showed it to be a compound of silica and a new earth, to which he gave the name of zirconia. He determined the properties of this new earth, and showed how it might be separated from other bodies and obtained in a state of purity. It has been since ascertained, that it is a metallic oxide, and the metallic basis of it is now distinguished by the name ofzirconium. In 1795 he showed that thehyacinthis composed of the same ingredients as the zircon; and that both, in fact, constitute only one species. This last analysis was repeated by Morveau, and has been often confirmed by modern analytical chemists.

It was in 1795 that he analyzed what was at that time calledred schorl, and nowtitanite. He showed that it was the oxide of a new metallic body, to which he gave the name oftitanium. He described the properties of this new body, and pointed out its distinctive characters. It must not be omitted, however, that he did not succeed in obtaining oxide of titanium, ortitanic acid, as it is now called, in a state of purity. He was not able to separate a quantity of oxide of iron, with which it was united, and which gave it a reddish colour. It was firstobtained pure by H. Rose, the son of his friend and pupil, who took so considerable a part in his scientific investigations.

Titanium, in the metallic state, was some years ago discovered by Dr. Wollaston, in the slag at the bottom of the iron furnace, at Merthyr Tydvil, in Wales. It is a yellow-coloured, brittle, but very hard metal, possessed of considerable beauty; but not yet applied to any useful purpose.

In 1797 he examined the menachanite, a black sand from Cornwall, which had been subjected to a chemical analysis by Gregor, in 1791, who had extracted from it a new metallic substance, which Kirwan distinguished by the name ofmenachine. Klaproth ascertained that the new metal of Gregor was the very same as his own titanium, and that menachanite is a compound of titanic acid and oxide of iron. Thus Mr. Gregor had anticipated him in the discovery of titanium, though he was not aware of the circumstance till two years after his own experiments had been published.

In the year 1793 he published a comparative set of experiments on the nature of carbonates of barytes and strontian; showing that their bases are two different earths, and not the same, as had been hitherto supposed in Germany. This was the first publication on strontian which appeared on the continent; and Klaproth seems to have been ignorant of what had been already done on it in Great Britain; at least, he takes no notice of it in his paper, and it was not his character to slur over the labours of other chemists, when they were known to him. Strontian was first mentioned as a peculiar earth by Dr. Crawford, in his paper on the medicinal properties of the muriate of barytes, published in 1790. The experiments on which he founded his opinions were made, he informs us, by Mr. Cruikshanks. Apaper on the same subject, by Dr. Hope, was read to the Royal Society of Edinburgh, in 1793; but they had been begun in 1791. In this paper Dr. Hope establishes the peculiar characters of strontian, and describes its salts with much precision.

Klaproth had been again anticipated in his experiments on strontian; but he could not have become aware of this till afterwards. For his own experiments were given to the public before those of Dr. Hope.

On the 25th of January, 1798, his paper on the gold ores of Transylvania was read at a meeting of the Academy of Sciences at Berlin. During his analysis of these ores, he detected a new white metal, to which he gave the name oftellurium. Of this metal he describes the properties, and points out its distinguishing characters.

These ores had been examined by Muller, of Reichenstein, in the year 1782; and he had extracted from them a metal which he considered as differing from every other. Not putting full confidence in his own skill, he sent a specimen of his new metal to Bergman, requesting him to examine it and give his opinion respecting its nature. All that Bergman did was to show that the metallic body which he had got was not antimony, to which alone, of all known metals, it bore any resemblance. It might be inferred from this, that Muller's metal was new. But the subject was lost sight of, till the publication of Klaproth's experiments, in 1802, recalled it to the recollection of chemists. Indeed, Klaproth relates all that Muller had done, with the most perfect fairness.

In the year 1804 he published the analysis of a red-coloured mineral, from Bastnäs in Sweden, which had been at one time confounded with tungsten; but which the Elhuyarts had shown to contain noneof that metal. Klaproth showed that it contained a new substance, as one of its constituents, which he considered as a new earth, and which he calledochroita, because it forms coloured salts with acids. Two years after, another analysis of the same mineral was published by Berzelius and Hisinger. They considered the new substance which the mineral contained as a metallic oxide, and to the unknown metallic base they gave the name ofcerium, which has been adopted by chemists in preference to Klaproth's name. The characters of oxide of cerium given by Berzelius and Hisinger, agree with those given by Klaproth to ochroita, in all the essential circumstances. Of course Klaproth must be considered as the discoverer of this new body. The distinction betweenearthandmetallic oxideis now known to be an imaginary one. All the substances formerly called earths are, in fact, metallic oxides.

Besides these new substances, which he detected by his own labours, he repeated the analyses of others, and confirmed and extended the discoveries they had made. Thus, when Vauquelin discovered the new earthglucina, in the emerald and beryl, he repeated the analysis of these minerals, confirmed the discovery of Vauquelin, and gave a detailed account of the characters and properties of glucina. Gadolin had discovered another new earth in the mineral called gadolinite. This discovery was confirmed by the analysis of Ekeberg, who distinguished the new earth by the name of yttria. Klaproth immediately repeated the analysis of the gadolinite, confirmed the results of Ekeberg's analysis, and examined and described the properties ofyttria.

When Dr. Kennedy discovered soda in basalt, Klaproth repeated the analysis of this mineral, and confirmed the results obtained by the Edinburgh analyst.

But it would occupy too much room, if I were to enumerate every example of such conduct. Whoever will take the trouble to examine the different volumes of the Beitrage, will find several others not less striking or less useful.

The service which Klaproth performed for mineralogy, in Germany, was performed equally in France by the important labours of M. Vauquelin. It was in France, in consequence of the exertions of Romé de Lisle, and the mathematical investigations of the Abbé Hauy, respecting the structure of crystals, which were gradually extended over the whole mineral kingdom, that the reform in mineralogy, which has now become in some measure general, originated. Hauy laid it down as a first principle, that every mineral species is composed of the same constituents united in the same proportion. He therefore considered it as an object of great importance, to procure an exact chemical analysis of every mineral species. Hitherto no exact analysis of minerals had been performed by French chemists; for Sage, who was the chemical mineralogist connected with the academy, satisfied himself with ascertaining the nature of the constituents of minerals, without determining their proportions. But Vauquelin soon displayed a knowledge of the mode of analysis, and a dexterity in the use of the apparatus which he employed, little less remarkable than that of Klaproth himself.

Of Vauquelin's history I can give but a very imperfect account, as I have not yet had an opportunity of seeing any particulars of his life. He was a peasant-boy of Normandy, with whom Fourcroy accidentally met. He was pleased with his quickness and parts, and delighted with the honesty and integrity of his character. He took him with him to Paris, and gave him the superintendence of his laboratory. His chemical knowledge speedily became great, and his practice in experimenting gave him skill and dexterity: he seems to have performed all the analytical experiments which Fourcroy was in the habit of publishing. He speedily became known by his publications and discoveries. When the scientific institutions were restored or established, after the death of Robespierre, Vauquelin became a member of the Institute and chemist to the School of Mines. He was made also assay-master of the Mint. He was a professor of chemistry in Paris, and delivered, likewise, private lectures, and took in practical pupils into his laboratory. His laboratory was of considerable size, and he was in the habit of preparing both medicines and chemical reagents for sale. It was he chiefly that supplied the French chemists with phosphorus, &c., which cannot be conveniently prepared in a laboratory fitted up solely for scientific purposes.

Vauquelin was by far the most industrious of all the French chemists, and has published more papers, consisting of mineral, vegetable, and animal analyses, than any other chemist without exception. When he had the charge of the laboratory of the School of Mines, Hauy was in the habit of giving him specimens of all the different minerals which he wished analyzed. The analyses were conducted with consummate skill, and we owe to him a great number of improvements in the methods of analysis. He is not entitled to the same credit as Klaproth, because he had the advantage of many analyses of Klaproth to serve him as a guide. But he had no model before him in France; and both the apparatus used by him, and the reagents which he employed, were of his own contrivance and preparation. I have sometimes suspected that his reagents were not always very pure; but I believe the true reason of the unsatisfactory nature of many of his analyses, is the bad choice made of the specimens selected for analysis. It is obvious from his papers, that Vauquelin was not a mineralogist; for he never attempts a description of the mineral which he subjects to analysis, satisfying himself with the specimen put into his hands by Hauy. Where that specimen was pure, as was the case with emerald and beryl, his analysis is very good; but when the specimen was impure or ill-chosen, then the result obtained could not convey a just notion of the constituents of the mineral. That Hauy would not be very difficult to please in his selection of specimens, I think myself entitled to infer from the specimens of minerals contained in his own cabinet, many of which were by no means well selected. I think, therefore, that the numerous analyses published by Vauquelin, in which the constituents assigned by him are not those, or, at least, not in the same proportions, as have been found by succeeding analysts, are to be ascribed, not to errors in the analysis, which, on the contrary, he always performed carefully, and with the requisite attention to precision, but to the bad selection of specimens put into his hand by Hauy, or those other individuals who furnished him with the specimens which he employed in his analyses. This circumstance is very much to be deplored; because it puts it out of our power to confide in an analysis of Vauquelin, till it has been repeated and confirmed by somebody else.

Vauquelin not only improved the analytical methods, and reduced the art to a greater degree of simplicity and precision, but he discovered, likewise, new elementary bodies.

The red lead ore of Siberia had early drawn the attention of chemists, on account of its beauty; and various attempts had been made to analyze it.Among others, Vauquelin tried his skill upon it, in 1789, in concert with M. Macquart, who had brought specimens of it from Siberia; but at that time he did not succeed in determining the nature of the acid with which the oxide of lead was combined in it. He examined it again in 1797, and now succeeded in separating an acid to which, from the beautiful coloured salts which it forms, he gave the name ofchromic. He determined the properties of this acid, and showed that its basis was a new metal to which he gave the name ofchromium. He succeeded in obtaining this metal in a separate state, and showed that its protoxide is an exceedingly beautiful green powder. This discovery has been of very great importance to different branches of manufacture in this country. The green oxide is used pretty extensively in painting green on porcelain. It constitutes an exceedingly beautiful green pigment, very permanent, and easily applied. The chromic acid, when combined with oxide of lead, forms either a yellow or an orange colour upon cotton cloth, both very fixed and exceedingly beautiful colours. In that way it is extensively used by the calico-printers; and the bichromate of potash is prepared, in a crystalline form, to a very considerable amount, both in Glasgow and Lancashire, and doubtless in other places.

Vauquelin was requested by Hauy to analyze theberyl, a beautiful light-green mineral, crystallized in six-sided prisms, which occurs not unfrequently in granite rocks, especially in Siberia. He found it to consist chiefly of silica, united to alumina, and to another earthy body, very like alumina in many of its properties, but differing in others. To this new earth he gave the name ofglucina, on account of the sweet taste of its salts; a name not very appropriate, as alumina, yttria, lead, protoxide of chromium, and even protoxide of iron, form salts whichare distinguished by a sweet taste likewise. This discovery of glucina confers honour on Vauquelin, as it shows the care with which his analyses must have been conducted. A careless experimenter might easily have confoundedglucinawithalumina. Vauquelin's mode of distinguishing them was, to add sulphate of potash to their solution in sulphuric acid. If the earth in solution was alumina, crystals of alum would form in the course of a short time; but if the earth was glucina, no such crystals would make their appearance, alumina being the basis of alum, and not glucina. He showed, too, that glucina is easily dissolved in a solution of carbonate of ammonia, while alumina is not sensibly taken up by that solution.

Vauquelin died in 1829, after having reached a good old age. His character was of the very best kind, and his conduct had always been most exemplary. He never interfered with politics, and steered his way through the bloody period of the revolution, uncontaminated by the vices or violence of any party, and respected and esteemed by every person.

Mr. Chenevix deserves also to be mentioned as an improver of analytical chemistry. He was an Irish gentleman, who happened to be in Paris during the reign of terror, and was thrown into prison and put into the same apartment with several French chemists, whose whole conversation turned upon chemical subjects. He caught the infection, and, after getting out of prison, began to study the subject with much energy and success, and soon distinguished himself as an analytical chemist.

His analysis of corundum and sapphire, and his observations on the affinity between magnesia and silica, are valuable, and led to considerable improvements in the method of analysis. His analyses ofthe arseniates of copper, though he demonstrated that several different species exist, are not so much to be depended on; because his method of separating and estimating the quantity of arsenic acid is not good. This difficult branch of analysis was not fully understood till afterwards.

Chenevix was for several years a most laborious and meritorious chemical experimenter. It is much to be regretted that he should have been induced, in consequence of the mistake into which he fell respecting palladium, to abandon chemistry altogether. Palladium was originally made known to the public by an anonymous handbill which was circulated in London, announcing thatpalladium, or new silver, was on sale at Mrs. Forster's, and describing its properties. Chenevix, in consequence of the unusual way in which the discovery was announced, naturally considered it as an imposition on the public. He went to Mrs. Forster's, and purchased the whole palladium in her possession, and set about examining it, prepossessed with the idea that it was an alloy of some two known metals. After a laborious set of experiments, he considered that he had ascertained it to be a compound of platinum and mercury, or an amalgam of platinum made in a peculiar way, which he describes. This paper was read at a meeting of the Royal Society by Dr. Wollaston, who was secretary, and afterwards published in their Transactions. Soon after this publication, another anonymous handbill was circulated, offering a considerable price for every grain of palladiummadeby Mr. Chenevix's process, or by any other process whatever. No person appearing to claim the money thus offered, Dr. Wollaston, about a year after, in a paper read to the Royal Society, acknowledged himself to have been the discoverer of palladium, and related the process by which he had obtained itfrom the solution of crude platina in aqua regia. There could be no doubt after this, that palladium was a peculiar metal, and that Chenevix, in his experiments, had fallen into some mistake, probably by inadvertently employing a solution of palladium, instead of a solution of his amalgam of platinum; and thus giving the properties of the one solution to the other. It is very much to be regretted, that Dr. Wollaston allowed Mr. Chenevix's paper to be printed, without informing him, in the first place, of the true history of palladium: and I think that if he had been aware of the bad consequences that were to follow, and that it would ultimately occasion the loss of Mr. Chenevix to the science, he would have acted in a different manner. I have more than once conversed with Dr. Wollaston on the subject, and he assured me that he did every thing that he could do, short of betraying his secret, to prevent Mr. Chenevix from publishing his paper; that he had called upon, and assured him, that he himself had attempted his process without being able to succeed, and that he was satisfied that he had fallen into some mistake. As Mr. Chenevix still persisted in his conviction of the accuracy of his own experiments after repeated warnings, perhaps it is not very surprising that Dr. Wollaston allowed him to publish his paper, though; had he been aware of the consequences to their full extent, I am persuaded that he would not have done so. It comes to be a question whether, had Dr. Wollaston informed him of the whole secret, Mr. Chenevix would have been convinced.

Another chemist, to whom the art of analyzing minerals lies under great obligations, is Dr. Frederick Stromeyer, professor of chemistry and pharmacy, in the University of Gottingen. He was originally a botanist, and only turned his attention to chemistry when he had the offer of the chemical chair at Gottingen. He then went to Paris, and studied practical chemistry for some years in Vauquelin's laboratory. He has devoted most of his attention to the analysis of minerals; and in the year 1821 published a volume of analyses under the title of "Untersuchungen über die Mischung der Mineralkörper und anderer damit verwandten Substanzen." It contains thirty analyses, which constitute perfect models of analytical sagacity and accuracy. After Klaproth's Beitrage, no book can be named more highly deserving the study of the analytical chemist than Stromeyer's Untersuchungen.

The first paper in this work contains the analysis of arragonite. Chemists had not been able to discover any difference in the chemical constitution of arragonite and calcareous spar, both being compounds of

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