-- 220 THE ANALYST. MONTHLY RECORD OF ANALYTICAL RESEAMHES INTO FOOD. WE are indebted to the enterprise of the Anericait Grocer Publishing Association for a very long aeries of analysis of Tea, by J. F. Geisler, of which the folloving is an abstract :- Taking the average of 6 andyses of Iudirtn tea ive find :-- Max.. mil. Average. Moisture ., .. . # 6.19 .. 6.66 .. 6.81 Half-hourExtract .. .. 39*66 .. 37*80 ., 38.17 Total Extra& . . . . 45-64 . . 41.32 . . 42.94 Insolubleleaf ., .. 63.07 ,. 48.63 . # 61.24 Tannin ., .. 18% .. 13.04 .. 14.87 Theine .. ., 3-30 ,. 1.80 .. 2% Soluble ash .. ,, 3*68 ., 3-24 .. 3*62 Insoluble ash .. ,. 2.22 ,. 1.93 ,. 2.12 AahincloI. in HCl .. .. 0296 .. -137 .. 0178THE ANALYST. 221 The average of thirteen varieties of Oolong tea yielded Max.Min. Average. Moisture . . .* . . 6-88 .. 5-09 *. 5.89 I-€alf-horu.Extraot ., ., 44.02 .. 34-10 ,* 37-88 TotalExtract .. .. 48-87 .. 40-60 ,. 43-32 Insolublcleaf ,, ,. 53.15 *. 44-80 ., 60-70 Tannin .. ,* 20.07 .. 11.93 ,. 16m38 Theine .. ., 3~50 .. 1*15 .. 2-32 Soluble ash .. .. 3*71 .. 2*60 .. 3.20 Insoluble ash ,, ,, 3.17 ,, 1’84 .. 2*68 Ash insol. in HCL , * . , -838 .. ,266 ,. *507 The czvel.tlge of eleven samples of Congou showed :- Max. Min. Average. Moisture .. . * .* 9-16 .. 7*65 ,. 8.37 Half-hourExtract .. .. 32.14 .. 23-48 ,. 28.40 TotalExtraot ,. .. 37.06 ,. 27.48 .. 34-35 Insoluble leaf .. .. 63-86 .. 54.50 .. 57.20 Tannin ., ., .. 13.89 .. 8.44 .. 11.54 Theine .. .. ,. 2.87 .. 1.70 ,, 2.37 Soluble ash ., . * .. 3.52 .. 2-25 ,, 3.06 Insoluble ash ,... 3-86 ,. 1.90 .. 2-68 Ashinsol. in HCl ,, ,. 1’31 ,. .32 .. *425 The (‘ half-hour extract ” is the result of boiling the tea for half an hour in 100 parts of distilled water, and is, in the author’s opinion, a better index of the quality of the ten than the ordinary total extract. The rest of the paper is devoted to the compari- 8on of the results of chemical analysis with commercial value, and it is shown that, although no absolutely unimpeachable ratio exists between them, yet the nearest results are got by infusing the tea for ten minutes, under b e d conditions, with 100 parts of boiling distilled water. Tables of the results so obtained are given, but as they are too long for abstraction, the reader is referred to the original article in the Amerionlz Grooe~. I n the Amhiv.der Pharmlr.cie there is a long paper on the (( Examination of Food, &a, containing Arseiiic,” by H. Beckurts.” It is an exhaustive and critical study of the different methods for the detection and estirnatiorz of arsenic in food and other organic substances. The author regards Fresenius and Babo’s method for the separation of arsenio from accompanying organic matter, by destroying the latter with hydrochloric acid and potassium chlorate, as inconvenient, and to be avoided. WGhler and Sieboldt’s method is looked upon with more favour. In this method the substance is heated with an equal weight of nitric acid in a porcelain dish, neutralised with pure potash, and, after the addition of potassium nitrate, evaporated to dryness, and ignited.The arseniate thus formed, is dissolved out by vater. Before testing the solution, however, in Marsh’ a apparatus, the nitrates and nitrites must be removed by evaporation with sulphuric acid.222 THE ANAIjYST. In criticising Schneider and Fyfe’s method, in which the arsenic is distilled out as arsenious chloride, by slowly adding sulphuric acid to a mixture of the substance to be examined with common salt, the author remarks that, of all the arsenic compounds, only arsenious acid is easily converted into arsenious chloride. The author then gives his and Herr Pehut’s researches, on a method by which arsenic compounds in organic substances can easily be determined. The substance to be examined is stirred up with hydroohloric acid (20-25 per cent.), free from arsenic, mixed with about 20 grms.of a 4 per cent. solution of ferrous chloride, and the mixture distilled froma large tubulated retort, the neck of which is directed upwards, and con- nected with a Liebig’s condensor. One-third is distilled at the rate of about 3 C.C. per minute. If the amount of arsenic present be not great, the whole of it will be in the first distillate. If larger quantities be present, the operation must, after the addition of another 100 0.0. of hydrochloric acid, be repeated. As ferrous chloride, according to Fischer, effectually prevents the volatilization of mercury, antimony, and tin in hydro- chloric acid solution, there is no fear of antimony and tin chloride being found in the distillate. The latter, after dilution, can be tested directly with Marsh’s apparatus. For quantitative determination the arsenic may be precipitated as sulphide by sulphu- retted hydrogen, or, after oxjdation, and the removal of the excess of hydrochloric acid, as ammonium-magnesium, arseniate, or, finally, volurnetrically, by titration with a standard iodine solution N.) I n this method the arsenic present as arsenious and arsenic acids distils over.Arsenious sulphide, which is often formed in putrefying organic matter containing arsenic, is also decomposed by the distillation. From the author’s quantitative experiments, the following have been a:Ilscted :- 1 . Arsenic Present tzs Arseniozts Acid-75 grms, of meat were mixed with 250 p. HCl, *01 grm. &Os and 200 0.0. 4 per cent. solution of ferrous chloride and distilled, The arsenic was determined ‘in the distillate as magnesium-ammonium arseniate : *00968 grm, A%03 was found. 2. Araefiic (GB Arsenic Act‘d.-300 gms. meat containing ai*senic acid equal to 001 gm. Aa03 were mixed with 20 gm. 4 per cmt. FeCL, and HCI 100 C.C. distilIed gave *00985 grm. As203. 3. Arsenious sulphicle was mixed with meat, and distilled as above. 42 per cent. hass was recovered from the distillate. 4. Metallic arsenic can also be easily detected even when not at all oxy&i~d.