ANALYTICAL CHEMISTRY. 3.86= 199 Examination of Wort and Starch. By E. W. T. JONES (Analyst, 12, 163—168).—The methods employed are essentially those described by O'Sullivan (this Journal, 1876, ii, 130). An analysis is given of a wort which gave [a] 3.84 116.5, and K = 50·8 (Trans., 1879, 606). The same wort analysed in the Inland Revenue Laboratory gave the values [a] = 120, and K = 57.2, on which numbers a charge of the addition of 1.6 per cent. of glucose was based. The suggestion is made that the higher value of K may have been obtained by the use of Fehling's solution volumetrically in the presence of dextrin. On keeping this wort for four months (after adding salicylic acid). the rotatory power diminished, whilst the cupric reducing power increased. Some of the same malt, mashed in the laboratory for three hours at 57-60°, gave [a] = 113·6, K = 51.85, from which it would appear that with some malts the limits recognised by the Inland Revenue chemists ([a] not less than 120, and K not over 51) may be exceeded. The method of analysing starch differs from that of O'Sullivan (Trans., 1884, 9) only in the omission of the washings with ether, alcohol, and warm water before gelatinising, and in controlling the results of the optical method by a subsequent hydrolysis with acid, and a determination by Fehling's solution. M. J. S. Estimation of Small Quantities of Lactic Acid. By W. WINDISCH (Chem. Centr., 1887, 826, from Wochenschr. f. Braueri, 13, 214). In order to estimate small quantities of lactic acid, the substance to be examined is heated with chromic acid, whereby the lactic acid is decomposed into formic acid and aldehyde. The mixed vapours are passed into Nessler solution, in which, in presence of an aldehyde, lead salts give a yellowish-red precipitate, or with smaller quantities, a yellowish opalescence. In order to examine roots by this process, they are first extracted with ether, which dissolves out all acid substances. V. H. V. New Method of Examining Butter. By T. T. P. B. WARREN (Chem. News, 56, 222, 231, 243-244).-Five grams of butter is placed in a tared tube, plugged with asbestos, and is extracted with carbon bisulphide. The fats are weighed, dissolved in carbon bisulphide, and well mixed with a solution of equal volumes of yellow sulphur chloride and carbon bisulphide; the latter is evaporated, and the thickened mass redissolved in carbon bisulphide, any insoluble residue indicating the presence of vegetable oils. The filter tube is dried and weighed; then by successive weighings after washing, first with water, then with ammonia, the dry matter, soluble substances, caseïn, &c., are determined. The sulphur chloride treatment applied to other fatty mixtures, such as lard, oil, or oleomargarin, will detect the admixture of any vegetable oil, rosin, rosin oil, or petroleum. After a few hours' contact with sulphur chloride, butter becomes brownish, commercial oleïn thickens and turns black, and animal oleïn assumes a very dark colour, but all dissolve in carbon bisulphide, whereas vegetable oils do not. Inasmuch as animal oils themselves dissolve vegetable oils, a small quantity of the latter might escape detection in presence of a large quantity of the former; to avoid this it is suggested to add to the butter or other fatty mixture sufficient tested cotton-seed oil to supersaturate the animal fats; then by treatment with sulphur chloride and subsequent washing with carbon bisulphide, the animal fats are removed, and the vegetable oils remain insoluble. Any excess residue over that due to the cottonseed oil added is derived from vegetable oil, present in the butter; this is, however, only approximately quantitative. Water must be absent when using sulphur chloride. Other precautions are noted, and some remarks are advanced on the character of the reaction of sulphur chloride on fats, and of the products formed in the reaction. Attention is drawn to the high percentage of caseïn in some samples of country butter, probably indicating the use of this substance as an adulterant. D. A. L. The Reichert-Meissl Process for the Estimation of Butter Fat. By R. WOLLNY (Bied. Centr., 1887, 699-703).-Errors frequently arise in the results obtained by working this process, the results being generally too high. This the author ascribes to the presence of carbonates in the potash used for saponification. A loss may also occur from the fact that distillation with sulphuric acid in presence of alcohol will produce ethereal salts of butyric and other acids, consequently the results may be too low. If the following precautions are taken, the results will be accurate. Instead of potassium hydroxide, a 50 per cent. sodium hydroxide solution is to be used, and allowed to settle before putting aside. Admission of carbonic anhydride to the saponifying solution must be avoided, and for this purpose the saponification must be conducted in a vessel to which a reflux condenser is attached, and the distillation of the alcohol should be effected without opening the apparatus. A closed T-tube is inserted between the flask and condenser, whereby, after distillation, water and acid can be added. As regards the process itself, 5 grams of the molten and filtered fat is accurately weighed into a 300 c.c. flask (length of neck 7 to 8 cm.), 2 c.c. of 50 per cent. sodium hydroxide solution, which has been preserved from all contact with carbonic anhydride, and 10 c.c. alcohol (96 vol. per cent.) are introduced into the flask, and after connection with the reflux condenser the flask is heated in the water-bath for hour; the alcohol is distilled off, and the heat continued for at least hour, 100 c.c. distilled water is then added, and the mixture further heated for hour, until the soap is dissolved. The clear solution is now to be decomposed whilst hot by 40 c.c. of sulphuric acid (30—35 c.c. = 2 c.c. of the soda solution), and a small piece of pumice should also be introduced. Distillation must be continued until 110 c.c. of the liquid has been collected, the distillate well mixed, and of it 100 c.c. filtered off and titrated with decinormal baryta, phenolphthalein being used as indicator. The figure thus obtained is to be multiplied by 11, and from the product are to be deducted such figures as are obtained from a preliminary blank experiment. The deduction to be made should not exceed 0:33. E. W. P. Examination of Cod-liver Oil and Vegetable Oils. By E. SALKOWSKI (Zeit. anal. Chem., 26, 557–582).-The determination of the temperature of solidification is of little assistance, since undoubtedly genuine specimens show widely different solidifying points. Moreover, cod-liver oil solidifies with extreme slowness, even at temperatures far below its freezing point, and an admixture of 20 per cent. of rape-seed, linseed, or cotton-seed oil, with an oil of low freezing point is not revealed at a temperature (0° C.) at which other genuine oils solidify. The presence of palm oil, palm kernel oil, or cocoa-nut oil may, however, be suspected if solidification occurs in 15 to 30 minutes at 0°. Treated by Reichert's process, cod-liver oil gives a very small quantity of volatile acid. Linseed, rape-seed, cotton-seed, and palm oils give a slightly higher yield, but not sufficiently different to enable this method to detect an admixture. When cod-liver oil is saponified and the dilute solution of the soap shaken with ether, cholesterin is extracted, together with a yellow substance, which seems to belong to the lipochrome series (Kühne, Untersuch. physiol. Inst. Heidelberg, 1882). This substance gives an indigo-blue colour with strong sulphuric acid, whilst cholesterin and also the cod-liver oil itself give violet. The fatty acids from the soap solution freed from cholesterin, when dissolved in chloroform and mixed with sulphuric acid, give a dark brown-red colour, with dirtygreen fluorescence. If after pouring off the chloroform some of the acid is added to glacial acetic acid, the mixture slowly acquires a fine red-violet colour, with dirty-green fluorescence. The only vegetable oils which in choloform solution are coloured blue by sulphuric acid are palm oil and cotton-seed oil. All the vegetable oils (except palm oil), when treated as above for the extraction of cholesterin, yielded a substance which was identified with the phytosterin of Hesse. This may be distinguished from cholesterin by its appearance under the microscope. A hot alcoholic solution of cholesterin solidifies on cooling to a mass of thin, rhombic plates, frequently showing reentering angles; the substance obtained from the vegetable oils forms stellate or fasciculate groups of thick needles, or on slow cooling gives elongated six-sided plates. The products from all the vegetable oils melted at 132-134° (Hesse's phytosterin at 132-133°). Cholesterin from genuine cod-liver oil melts at 146°; the product from an oil adulterated with 20 per cent. of rape, linseed, or cotton-seed oil melted at 139-140°, and showed the needles of phytosterin, together with the plates of cholesterin. Most of the specimens of cod-liver oil examined contained very little free fatty acid (0-24 to 0.69 per cent. calculated as oleic acid; one specimen, however, showed 6.5 per cent.). Since many vegetable oils give numbers lying within these limits, this character is of no service for their detection. M. J. S. Titration of Urea with Mercuric Nitrate. By E. PFLÜGER (Pflüger's Archiv, 40, 533–586).-After some critical remarks on von Rautenberg's and Pfeiffer's modifications of Liebig's method of estimating urea, a series of 28 experiments is detailed, in which the amount of nitrogen in urine was estimated first by Kjeldahl's method, and secondly by Rautenberg's mercurial solution. In some cases, the results by the latter were higher, in others lower than by Kjeldahl's method, and taking Kjeldahl's method as one which gives accurate results, it is calculated that the average error of Rautenberg's method is 0.7 per cent. On the average, out of 100 parts of the nitrogen in urine, 13 are combined in substances other than urea. Rautenberg's method does not give the amount of urea, but the total nitrogen. W. D. H. Fractional Reduction of Ortho- and Para-nitrotoluene and Quantitative Analysis of Ortho- and Para-toluidine. By T. MINIATI, H. BOOTH, and J. B. COHEN (J. Soc. Chem. Ind., 6, 418–420). -From a series of experiments on the reduction of ortho- and paranitrotoluene, it seems that both nitro-compounds are acted on concur. rently. Before commencing their analytical work, the authors thought it desirable to determine whether the reduction could be so regulated that approximately the same quantities of nitrotoluene could be reduced with a given quantity of the reducing agent; it was found that with care this could be readily accomplished. The separation and isolation of the nitrotoluene and toluidine is effected in the following manner :-After reduction, the acid solution obtained is distilled with steam, and the unattacked nitrotoluene driven over, the toluidine remaining behind. The toluidine solution is freed from tin by treatment with hydrogen sulphide and filtered. The filtrate is made alkaline and distilled with steam, when the toluidine distils over. Both distillates are extracted with ether, the ether is distilled off and the residues dried and weighed. The first gives the weight of nitrotoluene, the second that of the toluidine. Having the respective weights, an analysis of the one or the other and determination of the quantity of ortho- and para-compound present therein, suffices to find exactly how the reduction has gone. Having made unsuccessful attempts to analyse the resulting nitro-compound, the authors tried various methods for the quantitative estimation of ortho- and paratoluidine. The only process they found practicable was to add excess of oxalic acid solution, bring the precipitate on to a filter-paper, wash three or four times with ether, and weigh on a watch-glass. Any residue remaining in the precipitating vessel and in the filterpaper was dissolved in water and titrated with decinormal potash solution. With paratoluidine, it was found that precipitation was not complete unless the mixture was allowed to remain 12 hours. With pure orthotoluidine, there is no immediate precipitation, but in 12 hours from 4 to 5 per cent. of the ortho-compound crystallises out; hence in performing the analysis the error due to the precipitation of the ortho-compound must be allowed for if the solution remains 12 hours, or the error due to incomplete precipitation of the paracompound must be allowed for if the precipitate is filtered immediately. The better plan would therefore be to obtain an approximation of the amount of para-compound present in one determination, and then run in just sufficient oxalic acid solution to precipitate this Estimation of Small Quantities of Paratoluidine in Orthotoluidine. By C. HAEUSSERMANN (Chem. Ind., 10, 55—56).—Of the methods recommended for the estimation of para- and ortho-toluidine the process based on the titration of the para-compound with oxalic acid in an ethereal solution has been mostly adopted. It is not, however, wholly free from error, owing to the fact that the amount of ether to be used is frequently insufficient to completely dissolve the "ortho-oxalate" produced by the reaction. The author suggests the following method:- A solution containing 88 grams of crystallised oxalic acid in 750 c.c. of water and 43 c.c. of hydrochloric acid of 22° B. is heated in a porcelain basin to 70-75°, and treated with 10 grams of the toluidine under examination. When the precipitate which separates has been entirely redissolved, the mixture is allowed to cool gradually to 30-35° until the oxalate shows signs of crystallisation on the surface of the solution. It is then filtered through cotton and the residue washed with a few drops of water. The precipitate forms small, colourless scales having a dull appearance. The filtrate on standing deposits a further portion of crystals which are collected on a separate filter and washed. This operation is repeated until crystals are obtained having a lustrous appearance. These consist of the pure "ortho-oxalate," and are readily distinguished from the crystals of the para-compound. The crystalline fractions are then treated with a solution of sodium carbonate and subjected separately to distillation. The solidifying point of the distilled bases is determined by cooling a fraction of each distillate with ice. If the oil solidifies by merely agitating it, the crystals are collected on a tared filter, and after drying over sodium hydroxide weighed as paratoluidine. If, however, the addition of a few crystals of pure paratoluidine is required to induce solidification, only one-half of the mass is calculated as paratoluidine. If, on the other hand, it is impossible to solidify the base obtained from the distillation of the first crystalline fraction, orthotoluidine only is present in the sample under examination. With good toluidines, it generally suffices to collect and distil two fractions, in which case the base from the second crystallisation mostly constitutes a perfectly liquid oil. This method being inapplicable to mixtures containing more than 10 per cent. of paratoluidine, it is suggested to dilute such mixtures by the addition of pure orthotoluidine. D. B. Volumetric Determination of Alkaloïds by Mayer's Reagent. By F. S. HERETH (Zeit. anal. Chem., 26, 647).—To avoid the errors introduced by the use of filters and the irregular addition of the reagent (potassio-mercuric iodide), several equal portions of the solution to be titrated should be mixed at once with quantities of the reagent differing from one another by 01 c.c., and ranging from somewhat below the amount indicated by a rough preliminary test to an equal distance above. After settling for at least eight hours in a |
