Page:Proceedings of the Royal Society of London Vol 60.djvu/365

338 Dr. J. W; Pickemig. 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 endeavoured 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 have up to the present sunthesised seven different colloidal substances, 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 physiological reactions are described below.

Colloid a. Prepared by the interaction of equal parts of metaamido-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 beating for about six hours, although a similar substance is obtained by heating for half an hour at 130° 0. 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 are 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 xanthoproteic 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 and 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,whenThe resulting product appears as a number of translucent yellowish plates, which are tasteless and inodorous, and closely i esemble in appearance both Grimaux5s colloides 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


 * 1) FrShde, ‘ Annalen der Chemie,’ vol. 145, p. 376.