BY C. J. MARTIN AND FRANK TIDSWELL. 4S9 



(5) Nitric acid produced a precipitate which was not appr,-*- 



cialjly diminished by warming. 



(6) Picric acid produced a precipitate which was not appre- 



ciably diminished by warming. 



(7) Acetic acid produced no turVjidity. 



(8) Saturation with magnesium sulphate did not produce any 



precipitate. 

 (!)) Saturation with ammonium sulphate produced a precipi- 

 tate. This was filtered off and the filtrate contained no 

 proteid. 



From the above it is obvious that there were at least two 

 proteids present in our original solution — 



(1) A proteid coagulated by heat. 



(2) A proteid soluble at 100° C. 



The former appears from the above reactions to beloiig tj 

 the albumen class, as the presence of nucleo-albumen (nucleo- 

 proteid, Hammarsten) was excluded by the absence of any 

 precipitate of nuclein on submitting the clear solution of the 

 proteid in 2% HCl to pep bic digestion for some hours (12) at 37° C. 

 The albumen, however, had undergone digestion and had been 

 converted into deutero-proteose and peptone, for the solution now 

 reacted in the following manner : — 



(1) Boiling acidulated solution. No precipitate. 



(2) KHO + CuSO^. Strong pink biuret reaction. 



(3) HNO;,. No precipitate, but on further addition of NaCl 



turbidity which disappeared on heating and returned on 

 cooling the solution. 



(4) Saturation with Am o SO ^. Slight precipitate. Filtrate 



contained peptone. 



To detei'mine the nature of the proteid present in the filtrate 



after precipitation by heat, we boiled some of the solution which 



had been previously acidified with acetic acid, and separated the 



heat precipitate by filtration. An equal volume of trichloracetic 



34 



