TEE ANALYST. 357 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. The Detection of Added Water in Milk by Means of the Nitrate Test. M. Siegfeld. (Molkerei-Ztg. Hildesheim, 1902. xvi., 161, 162 ; through Zed. fur Untersuah. der Nahr. and Genussmittel, 1902, v., [18], 867.)-The author has com- pared the various reactions for detecting the presence of nitrates in milk, and finds that the formaldehyde test is as sensitive as the diphenylamine reaction. ’rhe former test should be made by allowing the milk, to which a drop of formaldehyde has been added, to run on to the surface of pure sulphuric acid. If nitrates be present a violet ring is formed at the junction of the two liquids. I t is not advisable to mix the acid and milk, as milk containing no nitrates gives a reddish-violet coloration, which may be mistaken for the nitrate reaction.(NOTE BY ABSTRACTOR.-Should the sulphuric acid contain a trace of iron, a blue ring is always obtained with milk containing formaldehyde, whether nitrates be present or absent.) w. P. s. Method for the Estimation of Metallic Impurities in Condensed Milk. J. W. Abbott. (Bull. Massachusetts Health Dept., 1900, 37; through Zeit. fuy Untersuch. der Nahr. und Genussmittel, 1902, V. [18], 866.)-The condensed milk is mixed in a china basin with a third of its weight of sulphuric acid, and subjected to an electric current of 1 to 4 amperes. After fifteen minutes’ treatment the whole mass becomes thorongly charred. The incineration is then readily completed over a free flame, and the ash may be employed for the estimation (electrolytical) of the metallic impurities which may be present.w. P. s. Determination of the Casein precipitated by Rennet. L. Lindet. ( A m . de Ch/im. wal., 1902, vii., 361-363.)-According to the author’s experience, the methods of determining casein in milk are not reliable, for the precipitation is358 THE ANALYST invariably incomplete ; and there is therefore no exact method of determining the value of milk for the purpose of cheese manufacture. The quantity of casein pre- cipitated by rennet under definite conditions can, however, be rapidly calculated from the depression in the speoific gravity of the separated milk after the addition of the enzyme. From the average results of his experiments the author finds that on the average the precipitation of each 3.5 grammes of casein per litre lowers the specific gravity of the whey by 1 degree.Hence the difference between the specific gravity of the separated milk and of the whey multiplied by 3.5 gives the amount of casein per litre precipitated by the rennet. Instead of separating the fat from the milk the specific gravity of the fat-free milk can be calculated by means of the formula- 100 D = a x 940 + (100 - a)D’, 100 D - a x 940 100-n ’ or D’= where D represents the specific gravity of the whole milk expressed in grammes, D‘ that of the separated milk, 940 that of the butter-fat in the milk, and a the per- cent age of butt er-fat. C. A. M. Separation and Estimation of Cholesterol in Butter Fat. A. Kirsten. (Zeit.fiir Unterszcch. der Nahr. und Genussmittel, 1902, v. [18], 849-856.)-Ten grammes of the melted fat are heated on a boiling-water bath under a reflux condenser for fifteen minutes with 20 C.C. of alcoholic potash, made as follows : 2 volumes of concentrated potassium hydroxide solution-1,000 grammes per litre-1 volume of water, and 7 volumes of absolute alcohol. Forty C.C. of water are then added, and, after cooling, 50 C.C. of ether. The contents of the flask in which the saponification has taken place are transferred to a separating funnel, and the flask is rinsed out with 50 C.C. of ether several times. The funnel is then shaken vigorously for one minute, and allowed to stand, the contents quickly separate. The ethereal layer is removed, and the soap solution shaken out five times with ether, using 50 C.C.of the latter each time. Should an emulsion form, a little alcohol may be added. The ether is distilled off from the combined extracts, and the alcohol remaining in the residue is removed by evaporation on the water-bath. The residue is then again heated with 10 C.C. of alcoholic potash, t o saponify traces of fat which it still contains, diluted with 30 C.C. of water, and shaken out with 100 C.C. of ether. After drawing off the soap solution, the ethereal layer is washed three times with 10 C.C. of 5 per cent. potassium hydroxide solution and twice with 10 C.C. of water. These washings are not added to the soap solution. After once more shaking the soap solution with 100 C.C. of ether, this second ethereal portion is also filtered into the weighed flask, and the filter washed with a little ether.The ether is then distilled off, and the residue of cholesterol is dried and weighed. The average amount of cholesterol found by the author in butter fat was about 0.46 per cent. At the commencement of lactation the quantity was 0.37 per cent., increasing a t the end The ether is filtered into a weighed flask. of the lactation period to 0.50 per cent. w. P. s.THE ANALYST. 359 Detection of '' Vinegar Essence " in Fermentation Vinegar. F. Rothen- bsch. (Deutsche Essigindustrie, 1903, vi., 49, 50 and 59-64; through Z e d . fur Untersuch. der Nahr. und Genussmittel, 1902, v., [17] , 817-819.)-The following methods are given : 1. Fifty C.C. of the vinegar are shaken in a separating-funnel with 20 to 30 C.C.of pure, alcohol-free chloroform. An emulsion is avoided by adding water and well cooling the mixture. The chloroform layer is filtered through a dry filter and again cooled, when a turbidity forms. On adding 2 to 3 C.C. of a mixture of 10 parts of concentrated sulphuric acid and 11 parts of fuming nitric acid, a dark-red zone appear8 between the two liquids should fermentation vinegar be present. By carefully shaking the mixture the whole chloroform layer becomes red-coloured, the acid layer remaining colourless. The red colour is very stable. Vinegar essence gives no coloured zone. 2. One C.C. of the sample, 0.1 C.C. of & iodine solution, and 0.2 C.C. of con- centrated sulphuric acid are mixed in a test-tube and cooled. Concentrated vinegar essence gives a clear, dark-red coloration, and water containing 1 per cent.of essence a clear yellow colour. Pure fermentation vinegar yields a dark-red coloration ; the fluid soon becomes turbid and opaque, and a greenish layer forms on the surface. Dilute fermentation vinegar gives a dark-red colour, soon becoming turbid. Mixtures of 100 C.C. of 10 per cent. fermentation vinegar with 20, 10, and 5 C.C. of vinegar essence give clear red colours; with less than 2.5 C.C. the mixture is still red, but soon becomes turbid. When fermentation vinegar is distilled the distillate yields a clear, bright-yellow colour, whilst the residue gives a turbid red coloration. Vinegar essence which has been allowed to stand in contact with vinegar shavings for a con- siderable time shows, when tested by this method, a dark-red colour which remains clear.Twenty C.C. of this dilute solution are placed in a wash-bottle, which is connected to a second wash-bottle containing 5 C.C. of sulphuric acid (1 : 3) and 19 C.C. of & permanganate solution. A strong regular current' of air, which has first been passed through an alkaline solution of permanganate, is drawn through the vinegar and permanganate solutions for two minutes. The wash-bottle containing the latter is then detached and placed for five minutes on a boiling-water bath. Ten C.C. of i& oxalic acid solution are then added, and the titration completed with i& permanganate. A blank test should be made, using 20 c.c of water. Vinegar essence destroys practically no permanganate.Fermentation vinegar, according to the amount of alcohol, etc., it contains, uses at least 1 C.C. of the permanganate. An attempt is made to render 3. The vinegar to be tested is diluted down to 1 per cent. this test quantitative, but without satisfactory results. w. P. s. The Estimation of Caffeine. J. Katz. (Zeds. f. angew. Chem., 1902, xxxix., 1013.)-The method is a modification of that of Beitter. Of the sample, 10 grammes are taken and shaken for half an hour with 200 grammes of chloroform and 0.5 gramme of ammonia. After settling, the chloroform solution is filtered through a Sander360 THE ANALYST. filter in order to obtain 150 grammes of clear water-free filtrate, The chloroform is distilled off entirely, and the residue is dissolved in 5 C.C.of ether, then 20 C.C. of 0.5 per cent. hydrochloric acid are added, and the ether is boiled away. When cold, the aqueous liquid is filtered, the flask and filter being washed several times with 0.5 per cent. hydrochloric acid, and the acid filtrate is shaken out four times with chloroform, using 20 C.C. each time. The chloroform solution is filtered if necessary, and the solvent is distilled off. The above method is used for coffee-beans, black tea, guarana, and kola-nuts. In the case of Paraguay tea, the material is treated with chloroform and ammonia as already described, the solution evaporated, and the residue dissolved in ether. Water is then added, the ether is boiled away, and 2 C.C. of water are introduced, having 5 per cent. of lead hydroxide in suspension. The liquid is heated for ten minutes on the water-bath, then a few decigrammes of calcined magnesia are added, and the liquid after cooling is filtered. The filtrate, which should be clear and only slightly coloured, is extracted in a, 6‘ perfora,tor3’ for two hours or shaken out with chloroform, and the extract is evaporated down. A. M. A Test for Phenacetin. F. H. Alcock and W. Wilkins. (Pharm. Jourm., 1902, 258.)-A purple coloration is obtained on strongly heating 0.01 gramme of phenacetin with 5 C.C. of pure sulphuric acid. On pouring the solution, when nearly cold, into a large bulk of water and adding ammonium hydroxide, a deep purple- coloured solution results. Should any charring have taken place, the solution must be filtered before making ammoniacal. Phenaeone, sulphonal, and acetanilide give entirely different results. w. P. s.