820 EXPEEIMENT STATION KECORD. 



the reagent used in the phospho-tungstic acid method. Zinc sulphate 

 a!> a precipitant of proteid.s was also compared with the reagents on 

 several materials. The following conclusions are drawn: 



"Phoppho-tungstic acid does not precipitate proteidy completely at 90 or 100° C. 

 "With phospho-tungstic acid as the precipitant, at 60°, very nearly the same 

 results are obtained on vegetable materials as by the Stutzer method. 

 "Bromin is not a suitable precipitant for pnjteids in vegetal )le materials. 

 ''The Stutzer method seems to be the metliod lea«t o])t'n to ol)jections." 



A ncTV method for the determination of nitric nitrogen, J. F. 



Pool {Jour. Plmnn. et Chiin.. 6. .ser.. 11 (1900), JVo. G, j)- '285; abs. in 

 Attn. Agroii., 26 (1900), Mj. 11., x?. oSo). — The solution containing the 

 nitrate is evaporated to dryness with sodiinn chlorid and decomposed 

 with sulphuric acid in an atmosphere of carbon dioxid. The hvdro- 

 chloric and nitric acids thus formed react upon each other, liberating 

 chlorin according to the following formula: 



OHCl + 2HN0, = 2NO + 4H,0 + HCl,. 



The chlorin is driven off from the solution, after dilution, and con- 

 ducted into a solution of potassium iodid, the iodin set free being 

 determined by titration with sodium hyposulphite. From the data 

 thus obtained the nitrogen present is calculated by means of the above 

 equation. 



Estimation of nicotin, amount of nicotin in Ne^v South Wales 

 tobaccos, (t. Hakker ( (Jheiii. Neir><^ HI {1900)., p. 273; ahs. in. Jour. 

 CJuiu. ^oc. [Londrni], 78 {1900), No. Jfo7, //, p. 775).— Comparative 

 tests were made of the methods of Kissling and Biel. The original 

 forms of these methods gave similar results, but the modification of 

 BieFs method involving the weighing of the double sulphates of nic- 

 otin and ammonia did not give satisfactory results. The same was 

 true of attempts to estimate nicotin volumetrically in the presence of 

 ammonia. No loss of nicotin was observed during the evaporation 

 of its solutions in ether. Four varieties of New South Wales tobacco 

 examined gave the following percentages of nicotin: Manila, 1.95; 

 Tamworth, 2.30; Tumut. 3.84; and Bathurst, 4.53. 



The . adulteration and analysis of the arsenical insecticides, 

 J. K. Haywood {Jour. Aruer. Chem. Soc, 22 {1900), ^^o. 9, pp. 508- 

 582). — The author reviews the work reported by a number of the 

 experiment stations on the composition and adulteration of insecticides 

 and reports trials of a number of methods of analysis that have been 

 suggested. His conclusions are as follows: 



" (1) Water can be determined in Paris green and Sclieele green by drying at the 

 temperature of boiling water for 12 to 15 hours. 



"(2) The best method for determining the total arsenious oxid in Paris and 

 Scheele greens is the Thorn-Smith method [E. S. R., 11, p. 614]. 



"(3) The best method for determining the soluble arsenious oxid in Paris and 

 .Scheele greens is by extracting with 500 cc. of water at room temperature. 



