EXPERIMENT STATION RECORD. 



Vol. XXXIII. Abstract Xuiviber. No. 6. 



RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICTJITTIRAL CHEMISTRY— AGROTECHNy. 



A rapid method of estimating nitrates, E. Knecht {Jour. Soc. Chem. Indus., 

 34 {1915), No. 3, pp. 126, 121). — Titauous hyclroxid causes an instantaneo^is 

 reduction of nitrates to ammonia. " When caustic soda is added to a solution 

 of a titanous salt, black titanous hydroxid is precipitated, but this begins 

 to decompose almost at once, yielding nascent hydrogen and the white titanic 

 hydroxid, probably according to the following equations : 



Ti2(SOi)3+6XaOH=Ti2(OH)o+3Na2S04; Ti.(OH)6+2H20=2Ti(OH)4+H2. 



"A convenient amount of nitrate for a single estimation is about the equiva- 

 lent of 0.1 gm. potassium nitrate. Thus, in the assay of a commercial sodium 

 nitrate, about 1 gm. is accurately weighed, dissolved in water, and made up to 

 100 cc. Of this, 10 cc. are measured into a copper flask, excess of caustic soda 

 is added, and then about 20 cc. of commercial titanous sulphate or chlorid. The 

 distillation can then at once be proceeded with and, after the boiling has been 

 continued for a quarter of an hour, the operation is fiaislied and back titration 

 is effected." 



Nitrites are also quantitatively reduced to ammonia by titanous hydroxid 

 when an excess of caustic alkali is present. 



The estimation of protein ammonia, L. W. Winkles {Ztschr. Angew. Ghent., 

 27 {1914), No. 56, Aufsat;:tcil, p. 44^^ fiO- li c&s. in Jour. Soc. CJiem. Indus., 

 S3 {1914), No. 15, p. 804)- — Instead of determining the organic matter in water 

 by making a cumbersome albuminoid ammonia determination, the author sug- 

 gests determining the protein ammonia. 



The method proposed consists essentially of treating 100 cc. of the water, 

 acidified with one drop of concentrated sulphuric acid, with 0.05 gm. of pure 

 powdered potassium persulphate, heating in the steam bath for 15 minutes, 

 cooling, and determining the ammonia in the fluid by the Nessler colorimetrlc 

 method, adding 5 cc. of a mixture of equal volumes of Nessler's reagent and a 

 solution of Rochelle salts. A second test is prepared in the same manner, with- 

 out heating, adding standard ammonium chlorid solution to equal the color of 

 the first test. Distillation is not necessary in the process. 



There are two disadvantages in the method, one being that even the purest 

 potassium persulphate contains ammonia, and the other, the unstability of the 

 potassium persulphate solution. The first can be obviated by recrystallization 



501 



