RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



Gravimetric determination of nitric acid. M. Buses Ber. Deut. Chem. < 

 88(1906), No. 8, pp. 861-866).— The method proposed is based upon the fact that 

 diphenyl-endanilo-dihydrotriazol, for which the author proposes the abbreviated 

 name "nitron," forms insoluble compounds with nitric acid, making it possible to 

 detect this acid in a dilution of 1 : 60,000 at room temperature and 1 :80,000 at 0° < '. 



The following substances, which also form insoluble compounds with the nitron, 

 ami bene- may interfere with the determination of nitric acid, arc enumerated: 

 Hydrogen bromid in dilutions of less than 1:800, hydrogen iodid in dilations of less 

 than 1 : 20, 000, nitrous acid in dilutions of less than ] :4,000, chromic acid in dilutions 

 of less than 1:6,000, chloric acid in dilution- of less than 1:4,000, perchloric acid in 

 dilutions of less than 1:50,000, all of which, except chloric and perchloric acids, may 

 be removed with comparative ease. 



Among the more rarely occurring substances which may interfere are Rhodan- 

 tua88ergtoffia dilution- of less than 1:15,000, ferro- and ferri-cyanid, picric acid, and 

 oxalic acid, the latter, however, not bein<r precipitated in a strong sulphuric-acid 

 solution. 



The method recommended is as follows: Dissolve an amount of the substance cor- 

 responding t'i 0.1 gm. of nitric acid in 80 to 100 cc. of water, add 10 drops of dilute 

 sulphuric acid, heat nearly to boiling, and add 10 to 12 cc. of the nitron acetate 

 solution i in per cent solution of nitron in 5 per cent acetic acid |; allow the Mask to 

 stand for ]\ t<. - hours in ice water and collect the precipitate on a Neubauer crucible; 

 run the filtrate through the crucible again, and when the solution has been com- 

 pletely removed wash with 10 to 12 cc of ice water, the wash water being added in 

 small portions and each portion completely removed before another is added: dry 

 the precipitate at 110° to constant weight, which can be done in \ hour. 



In calculating the results the formula C M H ltt N 4 . II\<> is used, the amount of 

 nitric acid pre-ent being estimated by multiplying the weight of the nitron nitrate 

 by 



A series of tests of the method on pure potassium nitrate are reported which show 

 a close agreement between the determined ami calculated amounts of nitric acid. 

 "When nitrites an- present they interfere with the accuracy of the determination and 

 must he removed. This is done by dissolving the substance in a small amount of 

 water (0.2 gm. in 5 to 6 cc. of waten and allowing the solution to drop slowly on 

 finely pulverized hydrazin sulphate (about ] gm. I, which decomposes the nitrites, 

 allowing the nitrogen to escape in the free state. 



The electrolytic oxidation of ammonia to nitrite, E. Mulleb and 1- . Spitzes 

 (Ber. Deut. Chem. Gesell., ?,$ (1905), .V... .;. pp. 778-782).— This article describes 

 apparatus and methods used and j:ives results obtained in electrolytically oxidizing 

 ammonia to nitrite in sodium bydroxid solution. The method used is based on the 

 work of Traube and Biltz. 



Studies on the action of different physical and chemical agents on the 

 gluten of wheat flour. E. Flkdkent - Ann. Sri. Aaron., :. ser., 9 < 1904 • II- A"- ■■'■ 

 [)}). 450-472). — On the basis of investigations extending over many years the author 



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