84 QUANTITATIVE ESTIMATION OF MERCURY IN ORGANIC COMPOUNDS ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS, Estimation of Theobromine and Caffeine in Cocoa and Chocolate, G. Savini. (Anoutli Chim. AppZic., 1916, 6, 247-250.)--Complete extraction of the fat from cocoa with a solvent causes more or less loss of the alkaloids. For example, on extracting the fat from 10 grms.of cocoa with petroleum spirit from 0-002 to 0404 grm. of the alkaloids was decomposed, whilst when carbon tetrachloride was used the amount of caffeine decomposed varied from 0.004 to 0.008 grm. In the following method this loss is obviated: 12 grms. of the finely powdered cocoa, or chocolate are heated on the water-bath for ten minutes with 70 c .c. of petroleum spirit in a 500 C.C.flrtsk, the extract decanted through a filter, and the process repeated twice. The filter-pper is returned to the flask, which is thenFOOD AND DRUGS ANALYSIS 85 heated for a few minutes in the water-oven to expel the solvent, and the residue is boiled for an hour beneath a reflux condenser with 5 C.C. of 10 per cent. sulphuric acid and about 250 C.C. of water.The hot liquid is poured off, the residue washed with hot water, and the solution and washings cooled to about 30" C., made up to 300 c.c., and filtered; 250 C.C. of the filtrate (= 10 grms. of the gample) are mixed with 10 grms. of fine sand and sufficient magnesia t o make the mass alkaline, and evaporated to a syrup, which is then mixed with 8 to 10 grms. more of magnesia so as t o convert it into a Clry powder.This is transferred to a flask and treated with 100 C.C. of chloroform, the basin and spatula being rinsed twice with 2.5 C.C. of hot water, which is added t o the chloroform in the flask. An addition of 0.25 C.C. of strong ammonia solution is then made, the liquid boiled for fifteen minutes beneath a reflux condenser, and decanted through a filter, and the residue again extracted, this time with 100 C.C.ctf chloroform only. This process is repeated three times more, so that, in all, 500 c..c. of chloroform have been used. The united extracts are evaporated to dryness on the water-bath, and the residue washed twice with 5 c.c., each time, of petroleum spirit, the washings being decanted through a small filter. Pinally the residue is taken up in a little boiling water, the solution filtered through the same filter, the insoluble residue washed three times with boiling water, the filtrate and washings evaporated, and the residue of theobromine and caffeine dried for an hour at 100" C. and weighed.C. A. M. Detection of Aracliis Oil in Olive Oil. R. Biazzo and S. Vigdorcik. (Annali Chim. AppZic., 1916, 6, 179-185.)-Twenty grms.of the oil are heated on a sand-bath with 40 C.C. of alcoholic potassium hydroxide (40 C.C. of 50 per cent. aqueous potassium hydroxide solution mixed with 100 C.C. af 96 per cent. alcohol and filtered through glass wool) until the liquid is homogeneous. It is then boiled for five minutes, the soap dissolved in 150 C.C. of water, and the fatty acids liberated by the addition of dilute sulphuric acid, and extracted with 200 C.C.of ether. The ethereal solution is wasb.ed twice with 150 C.C. of water, and then shaken for five minutes with 50 C.C. of .a 30 per cent. solution of normal lead acetate. The lead salts of the liquid fatty a,cids remain dissolved in tche ether, whilst those of the solid fatty acids separate out ;at the zone of contact of the ether and the aqueous layer.In the case of obstinate emulsions the particles of insoluble lead soaps are separated by filtering the aqueous layer, and are returned to the separating funnel. After separation of the aqueous layer the clear ethereal solution is decanted through a, dry filter, and the insoluble lead soaps are shaken for thirty minutes with 75 C.C.of ether at 15" C., and are then transferred to the filter and again washed with ether. They are then shaken in is separating funnel with 200 C.C. of ether and two successive portions of 100 C.C. of 20 per cent. hydrochloric acid, the ethereal layer containing the liberated fatty acids is washed with water, dried with calcium chloride, filtered and evaporated, and the residue of solid fatty acids tested for arachidic and ligno- ceric acids.For this purpose the following modification of the method of Kreis and Roth (ANALYST, 1913, 33, 160) is recommended: The solid fatty acids are dissolved in 50 C.C. of 90 per cent. alcohol (containing 10 droes of ;-hydrochloric acid per litre), the flask immersed in water a t 15" C. for thirty minut,es, and the crystals86 ABSTRACTS OF CHEMICAL PAPERS which separate dissolved in 25 C.C. of alcohol, which is cooled as before.If crystals are still obtained they are dissolved in 12.5 C.C. of alcohol, the solution again cooled, and any further crystals are dissolved in 5 C.C. of alcohol, which is then allowed to stand at the ordinary temperature. By this means it is possible to separate from olive oil containing 5 per cent.of arachis oil a sufficient quantity of crystals for the determination of the melting-point, which will be about 73.5" to 74" C. For the estimation of arachis oil the method of Tortelli and Ruggeri (ANALYST, 1898,23. 273) gives trustworthy results. The arachis oil used in the experiments cont,ained 4.65 per ce'nt . of arachidic and lignoceric acids.C. A. M. Detection of Rape Oil in Olive Oil. R. Biazzo and S. Vigdoreik. (Annali Chim. Applic., 1916,6,185-195.)-Twenty grms. of the oil are saponified as described in the preceding abstract, the fatty acids extracted with ether and sulphuric acid, the ethereal extract washed free from mineral acid, dried with calcium chloride and distilled, and the residue dried for fifteen minutes in the water-oven. The fatty acids are dissolved in 180 C.C.of anhydrous acetone, and t'he solution heated t o in- cipient boiling, treated with 20 C.C. of N-potassium hydroxide solution, and cooled at 15" C. The precipitated soaps are separated with the aid of a pump, washed four times with successive portions of 10 G.C. of cold acetone, and dissolved in water, and the solid fatty acids liberated by treatment with hydrochloric acid and lo0 C.C.of ether. The ethereal solution is washed twice with 100 C.C. of water each time, and shaken for five minutes with 15 C.C. of a 30 per cent. aqueous solution of lead acetate, and the insoluble lead soaps tested for arachidic and lignoceric acids (presence of arachis oil) as described in the preceding abstract.The ethereal solution, which will contain the lead salts of the liquid fatty acids and of erucic acid if rape oil be present, is mashed free from mineral acid, and hydrogenated in the presence of finely divided palladium. The ether is then distilled, and the hydrogenated fatty acids are fractionally crystallised by a modification of the method of Kreis and Roth (see preceding abstract).I f the last fraction melts above 71" C., the presence of behenic acid, produced by the hydrogenation of erucic acid, is indicated. As a rule, in the case of oils containing rape oil the melting-point of the crystals finally obtained is from 76" C. and upwards. Hydrogenation of erucic acid in ethereal solution yielded behenic acid melting at 78-5" C., and, after three recrystallisations from alcohol, at 82" C.Behenic acid is also characterised by its sparing solubility in 90 per cent. alcohol. C. A. M. Estimation of Sugars in the Presence of Gum. G. Savini. (Anwli Chim. AppZic., 1916, 6,250-255.)-1n the ordinary official methods of estimating sugars in gum pastilles, etc., the aqueous solution is treated with basic lead acetate, the excess of lead being afterwards removed by precipitation with sodium sulphate, phosphate or carbonate.Owing to the fact that gum arabic is not completely precipitated by basic lead acetate, the amounts of sugar estimated in the filtrate are inaccurate, the variations in the error depending upon whether the gum arabic was dextro- or laevo-rotatory. Better results are obtained by using a mixture of basic lead acetate and alcohol to separate the gum, as was first suggested by Chauvin.Twenty grms.BACTERIOLOGICAL, PHY STOLOGICAL, ETC. 87 of the substance under examination are dissolved in about 110 C.C. of hot water, and the solution cooled and treated with a mixture of 10 C.C. of basic lead acetate solution and 70 C.C. of 95 per cent. alcohol, which is added little by little with con- stant agitation.After standing for about an hour the liquid is diluted to 200 c.c., allowance being made f c r the v -ume of the precipitate, and is then filtered. An aliquot part (100 c.c.) of the filtrate is neutralised with a few drops of acetic acid, rapidly evaporated on the water-bath to expel the greater part of the alcohol, the residual liquid diluted to 100 c.c., and after the addition of a small quantity of alum to remove the excess of lead, it is again made up to 200 C.C. and filtered. The sugars in the filtrate are then estimated by the usual methods. The results given in detail show that the presence of gum arabic does not affect the accuracy of the estimation of cane sugar or dextrose, but that in the case of products containing invert sugar gum arabic has a certain influence upon the optical rotation, although even then the method is more accurate than the ordinary method. C. A. M.