396 THE PHOSPHORUS CONTENT OF THE 



105 C. for analysis. The following results indicate the purity 



of the product: 



N. p. 



per cent per cent. 



Hammarsten 16.65 0.847 



Jackson 16.53 0.862 



Casein from fifteen quarts of skimmed milk was placed in 

 seven litres of 0.4 per cent hydrochloric acid and warmed at 

 38 C. To this was added a dialyzed pepsin solution contain- 

 ing 0.75 grm. of commercial scale pepsin (1 : 3000). This 

 mixture was allowed to digest for two days at 38 C., at the 

 end of which time the undissolved residue was filtered off and 

 washed thoroughly with water. The undissolved matter was 

 again placed in three litres of 0.4 per cent hydrochloric acid 

 containing 100 c.c. of a 1 per cent dialyzed pepsin solution, 

 and allowed to digest at 38 C. for four days. Filtered from 

 this digestive mixture, the resulting residue was treated again 

 with a similar pepsin-hydrochloric acid solution and the pro- 

 teolysis continued for seven days at 38 C. As the quantity 

 of insoluble matter did not appear to decrease, it was filtered 

 from the acid fluid and washed with water until the washings 

 gave only a faint test for chlorides. 



It seemed possible that the apparent absence of organic 

 phosphorus hi Chittenden's preparations might be due to 

 the action of the alkali which had been used in redissolving 

 and purifying the paranuclein. In order to determine this 

 point, the paranuclein obtained in the above digestion was 

 divided into two portions, each of which was subjected to 

 the treatment outlined below. Furthermore, in order to pre- 

 clude the possibility of the formation of a large ash content 

 by the process of dialysis and precipitation employed by 

 Chittenden, the former process was omitted in preparation B. 



Preparation A. Paranuclein was dissolved in 1 per cent 

 sodium carbonate solution and filtered, thus removing the 

 larger part of the fat left adherent to the residue of digestion. 

 Upon addition of dilute hydrochloric acid to the alkaline fil- 

 trate, the paranuclein was thrown down as a heavy flocculent 

 precipitate. The latter was filtered, washed, and again dis- 



