456 



R. H. A. PLIMMER AND W. M. BAYL1SS. 



THE SOLUBLE P 2 5 . 



It was found by Biffi (3) that 27 per cent, of the total phosphorus of 

 caseinogen was converted into inorganic phosphoric acid by the action 

 of trypsin, the remainder being combined in an organic form not pre- 

 cipitable by magnesia mixture. It might be concluded from our results 

 that the whole of the phosphorus was changed into inorganic phosphoric 

 acid. The precipitation of albumoses and peptones by tannic acid, 

 however, is known to be by no means complete, at any rate in acid 

 solution such as we have employed, and a further investigation of the 

 nature of this soluble P 2 O S was necessary. For this purpose we employed 

 the method of precipitation of phosphates as ammonium magnesium 

 phosphate without previously oxidising the organic matter. 



(1) The soluble P 2 5 obtained by the action of 1 per cent, caustic 

 soda. The opalescent solution obtained by the action of 1 per cent, 

 alkali on caseinogen was first slightly acidified, in order to remove the 

 substance thrown down by acid, as above mentioned, in order that the 

 solution should contain less albuminous matter, which might hinder the 

 precipitation of the ammonium magnesium phosphate. The acid solu- 

 tion so obtained was then employed directly. It was made alkaline 



