tliis the enzyme was added. This solution was diluted with an 

 equal volume of water, 4 grains of sodium acetate added and laniiin 

 so long as a precipitate continues to be formed. The nitrate, ac- 

 cording to the author of this method, should contain any phos- 

 phoric acid split off by the action of enzymes. According to later 

 investigations, tannic acid in dilute mineral acid solution and tannic 

 acid in sodium acetate both failed to precipitate completely the 

 soluble luieleins contained in certain of the feeding material. 



The 1 1 art-Andrews 1 method is superior- to those just mentioned 

 yet it is not in itself reliable. The method briefly is as follows: 

 lix tract 5 grains of material for fifteen minutes in 125 cc. of 2 per 

 cent hydrochloric acid, filter, wash with water until the filtrate is 

 500 cc., neutralize 200 cc. of this with ammonium hydroxide pre- 

 cipitate at 65 degrees with 10 grains of ammonium nitrate and 25 cc. 

 of neutral ammonium niolybdate solution and 2 cc. of nitric acid'. 

 Sp. Gr. 1.20. Keep at this temperature fifteen minutes, allow to 

 cool and filter after one hour. Treat this precipitate in the usual 

 manner. .Dissolve in ammonia. Precipitate with magnesium mix- 

 ture and burn to the pyrophosphate, then redissolve and reprecipi- 

 tftte. The neutral ammonium molybdate is used to reduce the de- 

 composition of nucleic acid to a minimum. 



The method to be used in this study is the one employed by the 

 Ohio Experiment Station 2 . This method which has been brought 

 forward recently seems to be more accurate, since by investigation 

 they have found reason to question the Hart- Andrews method in 

 the following: 



1. Time allowed for extraction appears to be insufficient. 



2. The precipitate with neutral ammonium molybdate solution 

 end the minimum amount of acid is rendered difficult as a routine 

 method by the fact that 2 cc. of 1.20 nitric acid are in many case- 

 not nearly enough to cause precipitation. 



-'). The bulky flocculent precipitate which often formed may fre- 

 quently mask the yellow precipitate of inorganic phosphorus ren- 

 dering it impossible to tell when the precipitation is complete. 



1. The precipitate is difficult to filter. 



.">. The method involves the precipitating of inorganic phos- 

 phorus in the presence 1 of Phytin, a quantitative precipitation of in- 

 organic phosphorus alone from a solution containing Phytin ap- 

 pears to he impossible. 



(>. Nucleic arid may be hvdrolvzed by the nitric acid used in 



1. Bull 238, N. Y. Agr. Exp. Station. 



2. Bull. 2*5, Ohio Exp. Station. 



