PHOSPHORUS FROM CASEINOGEN. 



449 



this experiment and found to be f^ after 146 days, so that not only 

 phosphorus but also nitrogen was contained in the insoluble residue. 



In Experiment 4 the quantity of acid was 1 per cent. H 2 SO 4 . This 

 strength was chosen, since Langstein <14) ' (15) , who found that amino-acids 

 were produced from albumins on prolonged peptic digestion, employed 

 this quantity in his experiments and subsequently stated that 1 per 

 cent. H 2 SO 4 produced no amino-acids from albumin after one year's 

 action at 37 C. We have examined the effect of 1 per cent. H 2 S0 4 and 

 our result will be mentioned later. 



The fact that so much as two-thirds of the total phosphorus passed 

 into the soluble form does not agree with the result obtained by 

 Salkowski (16) , who stated that the whole of phosphorus of caseinogen 

 was converted into paranucleic acid by the action of pepsin, and that 

 this compound is precipitated by tannic acid. The prolonged digestion, 

 which was carried out by us, is sufficient to account for the difference in 

 our results, since paranucleic acid would most probably undergo further 

 change and be converted into a peptone containing phosphorus, which 

 is not thrown down by tannic acid. This explanation appears to be the 



