Reactions of certain Synthesized Proteid-Uke Substances. 347 



and Osborne* in studying the proteids of maize. The method was 

 rendered more accurate by Hewlett,f who substituted a bath of cod- 

 liver oil for the water bath usually employed as the heating medium, 

 and exhaustively dealt with the adverse criticisms made by Haycraft 

 and Duggan.J 



I have applied this method, using an oil bath, in the examination 

 of the proteid like colloids synthesised by Professor Grimaux and 

 myself. As pointed out in a previous section, in the entire absence 

 of salts these substances do not coagulate, even when boiled. For 

 the sake of comparison the following experiments were performed, 

 so as to satisfy the following conditions : (a) A 2 per cent, solution 

 of the substance under examination was always used, (b) The 

 diluent fluid always consisted of a 0*75 per cent, solution of sodium 

 chloride, (c) In each experiment 10 c.c of the fluid under examina- 

 tion was used, and the test-tubes were of uniform internal diameter. 

 By this means the mass to be heated remained constant, (d) The 

 thermometer was placed in the middle of the test-tube containing the 

 fluid under examination. 



The colloid A (" colloide amidobenzoique " of Grimanx) shows a 

 coagulation temperature of 70 to 71 C. 



The colloid B (of Grimaux) which is prepared from the same 

 reagents as the colloid A, but the temperature at which the reaction 

 of synthesis is conducted is allowed to rise to 130 C., shows on 

 heating one faint appearance of flocculi at 56 to 58 C., and a 

 second more pronounced coagulum at 70 to 72 C. 



The colloid C (" colloide aspartique " of Grimaux) on fractional 

 heating shows three distinct sets of flocculi, appearing respectively 

 at 58, 67, and 73'1 to 76'4 C. 



The colloid a, if care has been taken to keep the temperature of 

 preparation constant at 125 C., shows, on heating, only one coagu- 

 lum at 70'6 ; if, however, in the preparation of this colloid the tem- 

 perature of synthesis is allowed to rise, a second colloid coagulating 

 at 42 C. is often but not always formed. 



The colloid /3, even when the temperature of the synthesis has 

 been kept constant at 130 C., shows, on heating, three constituents 

 coagulating at 47 C., 56 C., and 74 C. 



The colloid 7 apparently only has one temperature of heat coagu- 

 lation, viz., 75 C. 



The colloid b coagulates at 75 C. 



The colloid e coagulates only at 47 C. 



The colloid coagulates at 48 and 59 C. 



* Chittenden and Osborne, ' Amer. Chem. Jo urn.' vol. 13, 7 and 8j vol. 14, 1. 

 t Hewlett, ' Journ. Physiol.,' vol. 13, p. 493, 1892. 



J Haycraft and Duggan, * Brit. Med. Journ.,' 1890, vol. 1, p. 167; ' Edin. Roy. 

 Soc. Proc.,' vol. 16, p. 361, 1888-9. 



