6 Journal of Agricultural Research voi. xvii, no. r 



ammoniacal silver-nitrate solution added, allowed to stand overnight, 

 filtered on the following morning, the residue on the paper washed until 

 all traces of ammonia were removed, and its nitrogen content determined. 



16. CrEatinin, — ^The method of Folin as modified by Kmmett and 

 Grindley (5) was used. An aliquot free from coagulable and insoluble 

 nitrogen and containing from 7 to 1 5 mgm. of creatinin was placed in a 

 500 cc. flask, 15 cc. of picric acid and 10 cc. of a 10 per cent solution of 

 sodium hydrate added, allowed to stand for five minutes, being agitated 

 several times in the interim, and then diluted to 500 cc. After mixing, 

 a portion of the solution was poured into one tube of a Duboscq color- 

 imeter and compared with NI2 potassium-bichromate solution contained 

 in the other tube, the scale of which was set at 8.0. 



Creatinin was calculated by the following formula : 



f 8.1 ^ Volume"! ^, _ milligrams of creatinin in the 

 i Reading 500""/ ''^ ^° ~ ^ aliquot taken. 



17. CrEatin. — To 5 cc. of the extract in a 50 cc. graduated flask, 

 10 cc. of Nil hydrochloric acid and 5 cc. of water were added, and the 

 solution heated in an autoclave at 135° C. for 30 minutes. It was then 

 cooled, 10 cc. of Nji sodium hydroxid added and the solution made to 

 volume with water. An aliquot was taken and creatinin determined as 

 above, with 30 cc. of 1.2 per cent picric acid and 10 cc. of a 10 per cent 

 solution of sodium hydroxid as suggested by Emmett and Grindley (5), 

 the result so obtained representing the total creatinin — creatinin due 

 to creatin and to preformed creatinin. The difference between the total 

 creatinin and the preformed creatinin multiplied by 1.16 represents the 

 creatin. 



1 8. Nitrates. — To a few drops on a porcelain spot plate of a reagent 

 containing o.i to 0.2 gm. of diphenylamin {4) in 100 cc. concentrated 

 sulphuric acid were added a few drops of the extract solution. In the 

 presence of nitrates a blue color developed. They were then quantita- 

 tively estimated by the Schlossing-Wagner method (9). 



DISCUSSION OF quantitative RESULTS 



The results of the quantitative chemical examination of the extracts 

 are presented in Table I and, calculated to a water-free basis, in Table II. 

 In Table III differences in the forms of nitrogen are shown. The per- 

 centages of creatin and creatinin appear in Table IV together with the 

 ratio between total nitrogen and the sum of the creatin and creatinin. 

 The percentages in this table are also calculated on a water-free basis. 



