9.1 × 0.154 × 100Per cent. of geraniol=————————=70.22.3825 - (9.1 × 0.042)
The percentage of combined alcohols can be calculated from the amount of ester found, and by subtracting this from the percentage of total alcohols, that of the free alcohols is obtained.
In the example quoted, the ester corresponds to 17.6 per cent. geraniol, and this, deducted from the total alcohols, gives 52.6 per cent. free alcohols, calculated as geraniol.
This process gives accurate results with geraniol, borneol, and menthol, but with linalol and terpineol the figures obtained are only comparative, a considerable quantity of these alcohols being decomposed during the acetylation. The aldehyde citronellal is converted by acetic anhydride into isopulegol acetate, so that this is also included in the determination of graniol in citronella oil.
Phenols.—These bodies are soluble in alkalies, and may be estimated by measuring 5 c.c. or 10 c.c. of the oil into a Hirschsohn flask (a flask of about 100 c.c. capacity with a long narrow neck holding 10 c.c., graduated in tenths of a c.c.), adding 25 c.c. of a 5 per cent. aqueous caustic potash solution, and warming in the water-bath, then adding another 25 c.c., and after one hour in the water-bath filling the flask with the potash solution until the unabsorbed oil rises into the neck of the flask, the volume of this oil being read off when it has cooled down to the temperature of the laboratory. From the volume of oil dissolved the percentage of phenols is readily calculated.
Aldehydes.—In the estimation of these substances, use is made of their property of combining with sodium bisulphite to form compounds soluble in hot water. From 5-10 c.c. of the oil is measured into a Hirschsohn flask, about 30 c.c. of a hot saturated solution of sodium bisulphite added, and the flask immersed in a boiling water bath, and thoroughly shaken at frequent intervals. Further quantities of the bisulphite solution are gradually added, until, after about one hour, the unabsorbed oil rises into the neck of the flask, where, after cooling, its volume is read off, and the percentage of absorbed oil, or aldehydes, calculated.
In the case of lemon oil, where the proportion of aldehydes, though of great importance, is relatively very small, it is necessary to first concentrate the aldehydes before determining them. For this purpose, 100 c.c. of the oil is placed in a Ladenburg fractional distillation flask, and 90 c.c. distilled off under a pressure of not more than 40 mm., and the residue steam distilled. The oil so obtained is separated from the condensed water, measured, dried, and 5 c.c. assayed for aldehydes either by the process already described, or by the following process devised by Burgess (Analyst, 1904, 78):—
Five c.c. of the oil are placed in the Hirschsohn flask, about 20 c.c. of a saturated solution of neutral sodium sulphite added, together with a few drops of rosolic acid solution as indicator, and the flask placed in a boiling water-bath and continually agitated. The contents of the flask soon become red owing to the liberation of free alkali by the combination of the aldehyde with part of the sodium sulphite, and this coloration is just discharged by the addition of sufficient10 per cent. acetic-acid solution. The flask is again placed in the water-bath, the shaking continued, and any further alkali liberated neutralised by more acetic acid, the process being continued in this way until no further red colour is produced. The flask is then filled with the sodium sulphite solution, the volume of the cooled unabsorbed oil read off, and the percentage of aldehydes calculated as before.
Solidifying Point, or Congealing Point.—This is of some importance in the examination of anise and fennel oils, and is also useful in the examination of otto of rose. A suitable apparatus may be made by obtaining three test tubes, of different sizes, which will fit one inside the other, and fixing them together in this way through corks. The innermost tube is then filled with the oil, and a sensitive thermometer, similar to that described under the Titre test for fats, suspended with its bulb completely immersed in the oil. With anise and fennel, the oil is cooled down with constant stirring until it just starts crystallising, when the stirring is interrupted, and the maximum temperature to which the mercury rises noted. This is the solidifying point.
In the case of otto of rose, the otto is continually stirred, and the point at which the first crystal is observed is usually regarded as the congealing point.
Melting Point.—This is best determined by melting some of the solid oil, or crystals, and sucking a small quantity up into a capillary tube, which is then attached by a rubber band to the bulb of the thermometer, immersed in a suitable bath (water, glycerine, oil, etc.) and the temperature of the bath gradually raised until the substance in the tube is sufficiently melted to rise to the surface, the temperature at which this takes place being the melting point.
The melting point of otto of rose is usually taken in a similar tube to the setting point, and is considered to be the point at which the last crystal disappears.
Iodine Absorption.—In the authors' opinion, this is of some value in conjunction with other data in judging of the purity of otto of rose. It is determined by Hübl's process as described under Fats and Oils, except that only 0.1 to 0.2 gramme is taken, and instead of 10 c.c. of chloroform, 10 c.c. of pure alcohol are added. The rest of the process is identical.
In the analysis of soap, it is a matter of considerable importance that all the determinations should be made on a uniform and average sample of the soap, otherwise very misleading and unreliable figures are obtained. Soap very rapidly loses its moisture on the surface, while the interior of the bar or cake may be comparatively moist, and the best way is to carefully remove the outer edges and take the portions for analysis from the centre. In the case of a household or unmilled toilet soap, it is imperative that the quantities for analysis should all be weighed out as quickly after each other as possible.
Fatty Acids.—Five grammes of the soap are rapidly weighed into a small beaker, distilled water added, and the beaker heated on the water bath until the soap is dissolved.
A slight excess of mineral acid is now added, and the whole heated until the separated fatty acids are perfectly clear, when they are collected on a tared filter paper, well washed with hot water and dried until constant in weight. The result multiplied by 20 gives the percentage of fatty acids in the sample.
A quicker method, and one which gives accurate results when care is bestowed upon it, is to proceed in the manner described above as far as the decomposition with mineral acid, and to then add 5 or 10 grammes of stearic acid or beeswax to the contents of the beaker and heat until a clear layer of fatty matter collects upon the acid liquor.
Cool the beaker, and when the cake is sufficiently hard, remove it carefully by means of a spatula and dry on a filtering paper, add the portions adhering to the sides of the beaker to the cake, and weigh.
The weight, less the amount of stearic acid or beeswax added, multiplied by 20 gives the percentage of fatty acids.
Care must be taken that the cake does not contain enclosed water.
The results of these methods are returned as fatty acids, but are in reality insoluble fatty acids, the soluble fatty acids being generally disregarded. However in soaps made from cocoa-nut and palm-kernel oils (which contain an appreciable quantity of soluble fatty acids) the acid liquor is shaken with ether, and, after evaporation of the ethereal extract, the amount of fatty matter left is added to the result already obtained as above, or the ether method described below may be advantageously employed.
Where the soap under examination contains mineral matter, the separated fatty acids may be dissolved in ether. This is best performed in an elongated, graduated, stoppered tube, the total volume of the ether, after subsidence, carefully read, and an aliquot part taken and evaporated to dryness in a tared flask, which is placed in the oven at 100° C. until the weight is constant.
In a complete analysis, the figure for fatty acids should be converted into terms of fatty anhydrides by multiplying by the factor 0.9875.
In this test the resin acids contained in the soap are returned as fatty acids, but the former can be estimated, as described later, and deducted from the total.
Total Alkali.—The best method is to incinerate 5 grammes of the soap in a platinum dish, dissolve the residue in water, boil and filter, making the volume of filtrate up to 250 c.c., the solution being reserved for the subsequent determination of salt, silicates, and sulphates, as detailed below.
Fifty c.c. of the solution are titrated with N/1 acid, to methyl orange,and the result expressed in terms of Na2O.
Number of c.c. required × 0.031 × 100 = per cent. Na2O.
The total alkali may also be estimated in the filtrate from the determination of fatty acids, if the acid used for decomposing the soap solution has been measured and its strength known, by titrating back the excess of acid with normal soda solution, when the difference will equal the amount of total alkali in the quantity taken.
The total alkali is usually expressed in the case of hard soaps as Na2O, and in soft soaps as K2O.
Free caustic alkaliis estimated by dissolving 2 grammes of the soap, in neutral pure alcohol, with gentle heat, filtering, well washing the filter with hot neutral spirit, and titrating the filtrate with N/10 acid, to phenol-phthalein.
Number of c.c. required × 0.0031 × 50 = per cent. free alkali Na2O, as caustic.
Free Carbonated Alkali.—The residue on the filter paper from the above determination is washed with hot water, and the aqueous filtrate titrated with N/10 acid, using methyl orange as indicator. The result is generally expressed in terms of Na2O.
Number of c.c. required × 0.0031 × 50 = per cent. free alkali Na2O, as carbonate.
Free Alkali.—Some analysts determine the alkalinity to phenol-phthalein of the alcoholic soap solution without filtering, and express it as free alkali (caustic, carbonates, or any salt having an alkaline reaction).
Combined Alkali.—The difference between total alkali and free alkali (caustic and carbonate together) represents the alkali combined with fatty acids. This figure may also be directly determined by titrating, with N/2 acid, the alcoholic solution of soap after the free caustic estimation, using lacmoid as indicator.
The potash and soda in soaps may be separated by the method described for the estimation of potassium inPearl ash(page 126).
The potassium platino-chloride (K2PtCl6) is calculated to potassium chloride (KCl) by using the factor 0.3052, and this figure deducted from the amount of mixed chlorides found, gives the amount of sodium chloride (NaCl), from which the sodium oxide (Na2O) is obtained by multiplying by 0.52991.
The potassium chloride (KCl) is converted into terms of potassium oxide (K2O) by the use of the factor 0.63087.
Saltmay be determined in 50 c.c. of the filtered aqueous extract of the incinerated soap, by exactly neutralising with normal acid and titrating with N/10 silver nitrate solution, using a neutral solution of potassium chromate as indicator. The final reaction is more distinctly observed if a little bicarbonate of soda is added to the solution.
Number of c.c. required × 0.00585 × 100 = per cent. of common salt, NaCl.
Chlorides may also be estimated by Volhard's method, the aqueous extract being rendered slightly acid with nitric acid, a measured volume of N/10 silver nitrate solution added, and theexcess titrated back with N/10 ammonium thiocyanate solution, using iron alum as indicator.
Silicates.—These are estimated by evaporating 50 c.c. of the filtered extract from the incinerated soap, in a platinum dish with hydrochloric acid twice to complete dryness, heating to 150° C., adding hot water, and filtering through a tared filter paper.
The residue is well washed, ignited, and weighed as SiO2, and from this silica is calculated the sodium silicate.
Sulphatesmay be determined in the filtrate from the silica estimation by precipitation with barium chloride solution, and weighing the barium sulphate, after filtering, and burning, expressing the result in terms of Na2SO4by the use of the factor 0.6094.
Moisture.—This is simply estimated by taking a weighed portion in small shavings in a tared dish, and drying in the oven at 105° C. until it ceases to lose weight. From the loss thus found is calculated the moisture percentage.
Free or Uncombined Fat.—This is usually determined by repeated extraction of an aqueous solution of the soap with petroleum ether; the ethereal solution, after washing with water to remove traces of soap, is evaporated to dryness and the residue weighed.
A good method, which can be recommended for employment where many determinations have to be performed, is to dissolve 10 grammes of soap in 50 c.c. neutral alcohol and titrate to phenol-phthalein with N/1 acid. Add 3-5 drops HCl and boil to expel carbonic acid, neutralise with alcoholic KOH solution and add exactly 10 c.c. in excess, boil for fifteen minutes under a reflux condenser and titrate with N/1 acid. The difference between this latter figure and the amount required for a blank test with 10 c.c. alcoholic KOH, denotes the amount of alkali absorbed by the uncombined fat.
Examination of the fatty acidsas a guide to the probable composition of the soap:—
From the data obtained by estimating the "titre," iodine number, and saponification equivalent of the mixed fatty and rosin acids, and the rosin content, a fairly good idea of the constitution of the soap may be deduced.
The titre, iodine number, and saponification equivalent are determined in exactly the same manner as described under Fats and Oils.
The presence of rosin may be detected by the Liebermann-Storch reaction, which consists in dissolving a small quantity of the fatty acids in acetic anhydride, and adding to a few drops of this solution 1 drop of 50 per cent. sulphuric acid. A violet coloration is produced with rosin acids. The amount of rosin may be estimated by the method devised by Twitchell (Journ. Soc. Chem. Ind., 1891, 804) which is carried out thus:—
Two grammes of the mixed fatty and rosin acids are dissolved in 20 c.c. absolute alcohol, and dry hydrochloric acid gas passed through until no more is absorbed, the flask being kept cool by means of coldwater to prevent the rosin acids being acted upon. The flask, after disconnecting, is allowed to stand one hour to ensure complete combination, when its contents are transferred to a Philips' beaker, well washed out with water so that the volume is increased about five times, and boiled until the acid solution is clear, a fragment of granulated zinc being added to prevent bumping. The heat is removed, and the liquid allowed to cool, when it is poured into a separator, and the beaker thoroughly rinsed out with ether. After shaking, the acid liquor is withdrawn, and the ethereal layer washed with water until free from acid. Fifty c.c. neutral alcohol are added, and the solution titrated with N/1 KOH or NaOH solution, the percentage of rosin being calculated from its combining weight. Twitchell suggests 346 as the combining weight of rosin, but 330 is a closer approximation.
The method may be also carried out gravimetrically, in which case petroleum ether, boiling at 74° C. is used for washing out the beaker into the separator. The acid liquor is run off, and the petroleum ether layer washed first with water and then with a solution of 1/2 gramme KOH and 5 c.c. alcohol in 50 c.c. water, and agitated. The rosin is thus saponified and separated. The resinate solution is withdrawn, acidified, and the resin acids collected, dried and weighed.
Halphen's Reaction.—This is a special test to determine the presence or absence of cotton-seed oil fatty acids in mixtures. Equal parts of the fatty acids, amyl alcohol, and a 1 per cent. solution of sulphur in carbon bisulphide, are heated in a test-tube placed in a water-bath until effervescence ceases, then in boiling brine for one hour or longer when only small quantities are present. The presence of cotton-seed oil is denoted by a pink coloration. The reaction is rendered much more rapid, according to Rupp (Z. Untersuch. Nahr. Genussm., 1907, 13, 74), by heating in a stoppered flask.
Other bodies which it is occasionally necessary to test for or determine in soap include:—
Carbolic acid.—Fifty grammes of the soap are dissolved in water and 20 c.c. of 10 per cent. caustic potash added. The solution is treated with an excess of brine, the supernatant liquor separated, and the precipitate washed with brine, the washings being added to the liquor withdrawn. This is then evaporated to a small bulk, placed in a Muter's graduated tube, and acidified with mineral acid.
The volume of separated phenols is observed and stated in percentage on the soap taken.
Or the alkaline layer may be rendered acid and steam distilled; the distillate is made up to a known volume, and a portion titrated by the Koppeschaar method with standard bromine water.
Glycerine.—Five grammes of soap are dissolved in water, decomposed with dilute sulphuric acid, and the clear fatty acids filtered and washed. The filtrate is neutralised with barium carbonate, evaporatedto 50 c.c., and the glycerol estimated by the bichromate method detailed under Crude Glycerine.
Starchorgummay be detected by dissolving the soap in alcohol, filtering, and examining the residue on the filter paper. Starch is readily recognised by the blue coloration it gives with a solution of iodine in potassium iodide.
Sugarsare tested for by means of Fehlings' solution, in the liquor separated from the fatty acids, after first boiling with dilute acid to invert any cane sugar.
Mercurywill be revealed by a black precipitate produced when sulphuretted hydrogen is added to the liquor separated from the fatty acids, and may be estimated by filtering off this precipitate on a tared Gooch's crucible, which is then dried and weighed.
Borax or boratesare tested for in the residue insoluble in alcohol. This is dissolved in water, rendered faintly acid with dilute hydrochloric acid, and a strip of turmeric paper immersed for a few minutes in the liquid. This is then dried in the water-oven, when if any boric acid compound is present, a bright reddish-pink stain is produced on the paper, which is turned blue on moistening with dilute alkali.
The amount of the boric acid radicle may be determined by incinerating 5-10 grammes of soap, extracting with hot dilute acid, filtering, neutralising this solution to methyl orange, and boiling to expel carbon dioxide. After cooling, sufficient pure neutralised glycerine is added to form one-third of the total volume, and the liquid titrated with N/2 caustic soda solution, using phenol-phthalein as indicator. Each c.c. of N/2 NaOH solution corresponds to 0.031 gramme crystallised boric acid, H3BO3or 0.0477 gramme crystallised borax, Na2B4O7·10H2O.
The amounts of caustic alkali (if any), carbonated alkali, and salt present are determined in the manner already described under Alkali and Alkali Salts. The glycerol content is ascertained by taking 2.5 grammes, adding lead subacetate solution, and filtering without increasing the bulk more than is absolutely necessary; the solution is concentrated to about 25 c.c., and the oxidation with bichromate and sulphuric acid conducted as described in the examination of Crude Glycerine. The solution, after oxidation, is made up to 250 c.c., and titrated against standard ferrous ammonium sulphate solution, the formula for the calculation being:—
Per cent. of glycerol=(0.25 - (2.5/n)) × 40
where n equals the number of c.c. of oxidised lyes required to oxidise the ferrous ammonium sulphate solution.
The estimation of actual glycerol in this is necessarily a matter of considerable importance, and a very large number of processes, which are constantly being added to, have been suggested for the purpose. Hitherto, however, only two methods have been generally adopted,viz.the acetin and the bichromate processes. Unfortunately the results obtained by these do not invariably agree, the latter, which includes all oxidisable matter as glycerol, giving sometimes considerably higher results, and it has been suggested that a determination should be made by both methods, and the average of the two results considered the true value. This involves a considerable amount of time and trouble, and it will generally be found sufficient in a works laboratory to determine the glycerol by one method only in the ordinary course, reserving the other process for use as a check in case of dispute or doubt.
Acetin Method.—This consists in converting the glycerol into its ester with acetic acid, the acetic triglyceride, or triacetin being formed. This is then saponified with a known volume of standard alkali, the excess of which is titrated with acid, and the percentage of glycerol calculated from the amount of alkali absorbed.
From 1 to 1.5 grammes of the glycerine is weighed into a conical flask of about 150 c.c. capacity, 7 or 8 c.c. of acetic anhydride added, together with about 3 grammes of anhydrous sodium acetate, and the whole boiled on a sand-bath under a reflux condenser for one to one and a half hours, after which it is allowed to cool, 50 c.c. water added, and the ester dissolved by shaking, and gently warming, the reflux condenser still being attached as the acetin is very volatile. The solution is then filtered from a white flocculent precipitate, which contains most of the impurities, into a larger conical flask, of some 500-600 c.c. capacity, and after cooling, rendered just neutral to phenol-phthalein by means of N/2 caustic soda solution, the exact point being reached when the solution acquires a reddish-yellow tint; 25 c.c. of a strong caustic soda solution is then added, and the liquid boiled for about fifteen minutes, the excess of alkali being titrated after cooling, with N/1 or N/2 hydrochloric acid. A blank experiment is carried out simultaneously, with another 25 c.c. of the soda solution, and the difference in the amounts of acid required by the two, furnishes a measure of the alkali required to saponify the acetin formed, and hence the amount of glycerol in the crude glycerine may be calculated.
Example.—1.4367 grammes crude glycerine, after treatment with acetic anhydride, and neutralising, was saponified with 25 c.c. of a 10 per cent. caustic soda solution.
The blank experimentrequired111.05 c.c.N/1hydrochloric acid.Flask containing acetin"75.3 c.c.""——35.75 c.c.""
Hence, the acetin formed from the glycerol present in 1.4367grammes of the crude glycerine required 35.75 c.c. N/1 caustic alkali for its saponification, so that the percentage of glycerol may be calculated from the following formula:—
35.75 × 0.03067 × 100Per cent. glycerol=———————=76.3.1.4367
Bichromate Method.—This process was originally devised by Hehner (Journ. Soc. Chem. Ind., 1889, 4-9), but the modification suggested by Richardson and Jaffe (ibid., 1898, 330) is preferred by the authors, and has been practised by them for several years with perfectly satisfactory results.
Twenty-five grammes of the crude glycerine are weighed out in a beaker, washed into a 250 c.c. stoppered flask, and made up to the graduation mark with water. Twenty-five c.c. of this solution are then measured from a burette into a small beaker, a slight excess of basic lead acetate solution added to precipitate organic matter, the precipitate allowed to settle, and the supernatant liquid poured through a filter paper into another 250 c.c. flask. The precipitate is washed by decantation until the flask is nearly full, then transferred to the filter, and allowed to drain, a few drops of dilute sulphuric acid being added to precipitate the slight excess of basic lead acetate solution, and the contents of the flask made up with water to 250 c.c. This solution is filtered, 20 c.c. measured from a burette into a conical flask of about 150 c.c. capacity, 25 c.c. of a standard potassium bichromate solution containing 74.86 grammes bichromate per litre added, together with 50 c.c. of 50 per cent. sulphuric acid, and the whole placed in a boiling water-bath for one hour, after which it is allowed to cool, diluted with water to 250 c.c., and this solution run in to 20 c.c. of a 3 per cent. ferrous ammonium sulphate solution until the latter is completely oxidised, as shown by no blue coloration being produced when one drop is brought into contact with one drop of a freshly prepared solution of potassium ferricyanide on a spot-plate. The ferrous ammonium sulphate solution is previously standardised by titration with a potassium bichromate solution of one-tenth the above strength, made by diluting 10 c.c. of the strong solution to 100 c.c. with water.
The reaction taking place in the oxidation may be represented by the equation:—
3C3H5(OH)3+ 7K2Cr2O7+ 28H2SO4= 9CO2+ 40H2O + 7K2SO4+ 7Cr2(SO4)3.
Now the strong potassium bichromate solution above mentioned is of such a strength that 1 c.c. will oxidise 0.01 gramme glycerine, and 20 c.c. of the ferrous ammonium sulphate solution should require about 10 c.c. of the one-tenth strength bichromate in the blank experiment. If it requires more or less than this, then the amount of ferrous ammonium sulphate solution which would require exactly 10 c.c. (correspondingto 0.01 gramme glycerine) is calculated, and the oxidised glycerine solution run into this until oxidation is complete.
The formula for the calculation of the percentage of glycerol then becomes:—
Per cent. of glycerol=(0.25 -((250 × 0.01)/n))×500,
where n equals the number of c.c. of oxidised glycerine solution required to oxidise the ferrous ammonium sulphate solution.
Example:—
In the blank experiment 20 c.c. ferrous ammonium sulphate solution required 9.8 c.c. one-tenth strength bichromate solution, so that 20.4 c.c. ferrous solution would equal 10 c.c. bichromate.
20.4 c.c. ferrous solution required 27.8 c.c. of oxidised glycerine solution before it ceased to give a blue coloration with potassium ferricyanide.
Therefore, per cent. of glycerol= (0.25 -((250 × 0.01)/27.8))×500,= 80.04 per cent.
Other methods have been suggested for the preliminary purification,e.g., silver oxide, silver carbonate and lead subacetate, and copper sulphate and caustic potash, but the lead subacetate alone with care gives satisfactory results.
Other determinations include those of specific gravity, alkalinity, proportion of salts and chloride, and tests for metals, arsenic, sulphur compounds, sugar, and fatty acids.
Specific gravityis determined at 15° C., and may be taken in specific gravity bottle, or with a Westphal balance or hydrometer It usually ranges from 1.3 to 1.31.
Alkalinity, which is usually sodium carbonate, and may be somewhat considerable if the soap has been grained with caustic alkali, is determined after dilution with water by titrating with N/2 acid, using methyl orange as indicator.
Salts.—These may be determined by gently incinerating 5-6 grammes of the glycerine, extracting the carbonaceous mass with distilled water, filtering, and evaporating the filtrate on the water bath. The dried residue represents the salts in the weight taken.
Chloride of sodium(common salt) may be estimated by dissolving the total salts in water, adding potassium chromate, and titrating with N/10 silver nitrate solution.
Copper,lead,iron,magnesium, andcalciummay also be tested for in the salts, by ordinary reactions.
Arsenicis best tested for by the Gutzeit method. About 5 c.c. is placed in a test-tube, a few fragments of granulated zinc free from arsenic, and 10 c.c. dilute hydrochloric acid added, and the mouth of the tube covered with a small filter paper, moistened three successive times with an alcoholic solution of mercury bichloride and dried.After thirty minutes the filter paper is examined, when a yellow stain will be observed if arsenic is present.
Sulphates.—These may be precipitated with barium chloride in acid solution, in the usual way, dried, ignited, and weighed.
Sulphitesgive with barium chloride a precipitate soluble in hydrochloric acid. If the precipitate is well washed with hot water, and a few drops of iodine solution together with starch paste added, the presence of sulphites is proved by the gradual disappearance of the blue starch-iodine compound first formed.
Thiosulphatesare detected by precipitating any sulphite and sulphate with barium chloride, filtering, acidifying, and adding a few drops of potassium permanganate solution, when in the presence of a mere trace of thiosulphate, the solution becomes cloudy.
Sulphides.—Lewkowitsch recommends testing for these by replacing the mercury bichloride with lead acetate paper in the Gutzeit arsenic test. Any sulphide causes a blackening of the lead acetate paper.
Sugarsmay be tested for both before and after inversion, by boiling with Fehlings' solution, when no reduction should take place, if pure.
Fatty acidsare detected by the turbidity they produce when the diluted glycerine is acidified.
Until the year 1853 the amount of soap produced annually in this country was readily obtainable from the official returns collected for the purpose of levying the duty, and the following figures, taken at intervals of ten years for the half century prior to that date, show the steady development of the industry during that period:—
Year.Manufactured.Consumed.Exported.Duty per Ton.Cwts.Cwts.Cwts.£1801509,980482,14026,790211811678,570651,78026,790211821875,000839,29035,7102818311,098,210955,360142,8502818411,776,7901,517,860258,9301418511,937,5001,741,070196,43014
Since the repeal of the soap duty, the revenue from which had reached about £1,000,000 per annum, no accurate means of gauging the production exists, but it is estimated that it has nearly quadrupled during the last fifty-five years, being now some 7,000,000 or 8,000,000 cwt. per annum.
The number of soap manufacturers in the United Kingdom is nearly 300, and the amount of capital invested in the industry is roughly estimated to approach £20,000,000 sterling.
Official figures are still available for the amount and value of soap annually imported and exported to and from the United Kingdom, the returns for the last eight years being:—
Household.Toilet.Total.[13]Year.Quantity.Value.Quantity.Value.Quantity.ValueCwts.£Cwts.£Cwts.£1900............191,233244,3451901............302,555315,0261902............361,851429,3001903273,542284,37625,74998,032462,959499,4071904254,425268,40817,96281,162383,122438,9661905274,238279,04419,63198,507473,067500,4301906309,975311,11418,554101,243399,070468,0861907228,035263,96518,24499,432504,710545,385
Household and toilet soaps were not given separately prior to 1903.
The imports during the last three years for which complete figures are obtainable, came from the following sources:—
1904.1905.1906.£££From Netherlands4,3153,6203,368France14,33917,78324,747Italy24,20918,12932,972United States218,740235,612242,294Other Foreign Countries6,7853,8737,448Total from Foreign Countries268,388279,017310,829Total from British Possessions2027285Total268,408279,044311,114
1904.1905.1906.£££From Germany3,5093,5163,001Netherlands5,9375,7735,919Belgium1,5681,8613,145France7,1207,6335,794Italy1,1762551,233United States59,86374,51678,382Other Foreign Countries166147196Total from Foreign Countries79,33993,70197,670Total from British Possessions1,8234,4113,225Total81,16298,112100,895
The exports from the United Kingdom during the past eight years have been as follows:—
Household.Toilet.Total.[14]Year.Quantity.Value.Quantity.Value.Quantity.Value.Cwts.£Cwts.£Cwts.£1900............874,214939,5101901............947,485999,5241902............1,051,6241,126,6571903998,995900,81438,372217,9281,057,1641,143,66119041,049,022955,77440,406228,5741,108,1741,208,71219051,167,9761,013,83743,837248,4251,230,3101,284,72719061,131,2941,009,65346,364261,1861,210,5981,309,55619071,114,6241,095,17050,655280,1861,240,8051,459,113
Household and toilet soaps were not given separately prior to 1903.
The exports for the last three years for which complete figures are available, consisted of the following:—
1904.1905.1906.£££To Sweden3,0272,9113,677Norway4,1733,9216,005Netherlands39,42041,19748,601Dutch Possessions in the Indian Seas8,58610,2937,746Belgium73,99651,5837,729France11,74112,22222,907Portuguese East Africa28,98742,98140,478Canary Islands24,76327,86427,579Italy2,8423,1873,962Turkey6,9747,8585,897Egypt12,1109,46712,035China (exclusive of Hong-Kong and Macao)49,235114,15689,169United States3,8851,9753,924Columbia3,6015011,364Ecuador3,0753,0966,861Chili5,9724,8659,203Brazil35,19728,19831,726Argentine Republic7,8028,95413,084Other Foreign Countries40,05853,91477,687Total to Foreign Countries365,444429,143419,634To Channel Islands5,3018,3287,968Gibraltar13,27213,86812,661British West Africa—Gold Coast22,59818,51323,423Lagos7,7518,0329,518Nigerian Protectorate14,94215,29920,951Cape of Good Hope158,517143,750136,388Natal74,84871,87446,771British India—Bombay (including Kurachi)59,40668,94577,867Madras6,3646,69710,355Bengal, Eastern Bengal and Assam.26,53423,08722,648Burmah26,38935,72737,103Straits Settlements and Dependencies26,51632,21439,749Hong-Kong14,11915,15315,685British West India Islands74,06958,88167,331British Guiana12,66112,02311,557Other British Possessions47,04352,30350,044Total to British Possessions590,330584,694590,019Total955,7741,013,8371,009,653