338 Dr. J. W, Pickering. The Chemical and Physiological 



of the Norway hare (^Lepus variabilis), during" its albino condition, 

 these substances fail to induce intravascular coagulation of the blood, 

 although they hasten the coagulation of the blood when drawn from 

 the carotids, in a precisely similar manner to nucleo-proteids. 



Taking these facts as the basis of my investigations, I have en- 

 deavoured to synthesise substances which will approach more nearly 

 in their chemical and physiological reactions to proteids than those 

 briefly described above ; and to further investigate the properties of 

 Grimaux's colloids. 



I. General Description of Experiments. 



I have up to the present synthesised seven different colloidal sub- 

 stances, by the interaction of either phosphorus pentachloride or 

 pentoxide on certain well-known derivatives of proteids, and the 

 details of their preparation, physical properties, chemical and physio- 

 logical reactions are described below. 



Colloid a. Prepared by the interaction of equal parts of meta- 

 amido-benzoic acid, biuret, and three times its weight of phosphorus 

 pentoxide at 125 C. in a sealed tube. The best results are obtained 

 by continuing the heating for about six hours, although a similar 

 substance is obtained by heating for half an hour at 130 C. The 

 product of the reaction is a pinkish-grey friable powder, which is 

 insoluble in cold water, and almost insoluble in boiling water. 

 This substance should be repeatedly washed until all traces of 

 phosphoric acid a.re removed. When heated with Millon's reagent 

 it fails to give the reaction characteristic of tyrosine and proteids ; 

 it also does not give the well-known colour reactions with the 

 salts of copper, nickel, cobalt, and caustic potash. It gives the 

 typical blue reaction associated with the name of Frohde* when 

 heated with sulphuric and molybdic acids, as well as the xantho- 

 proteic reaction. 



If the amount of biuret exceeds the amount of meta-amido-benzoic 

 acid, then the excess of biuret left over gives its typical colour 

 reaction with copper sulphate ancl potash. 



The pinkish-grey powder, obtained by the reaction described 

 above, should be dissolved in ammonium hydrate, and the resulting 

 solution evaporated down at the temperature of the atmosphere in 

 vacuo, when the resulting product appears as a number of translucent 

 yellowish plates, which are tasteless and inodorous, and closely 

 resemble in appearance both Grimaux's " collo'ides amido-benzoique 

 and aspartique " and dried serum-albumen. These plates are with 

 difficulty soluble in cold water, but readily pass into solution on 

 warming. The solution obtained does not coagulate on heating, but 



* Frohde, ' Annalen der Chemie,' vol. 145, p. 376. 



