220 



SOAPS AND PROTEINS 



single experiment, chosen from many, may serve to illustrate 

 the point. 



In Table LXIX and Fig. 109 is shown how the addition of a 

 fixed alkali to an otherwise solid gelatin gel liquefies this. 



TABLE LXIX 



NEUTRAL GELATIN GEL AND ALKALI 



The mixtures were liquefied in a warm-water bath. After standing for twenty-four 

 hours at 25 C. the gelatin in tube 1 was solid; that in tubes 2, 3, 4 and 5 was also solid; 

 in tube 6 the surface quivered on shaking. The gelatin in tube 7 flowed as a viscid liquid. 

 In the remaining tubes the gelatin was entirely liquid. 



TABLE LXX 

 NEUTRAL GELATIN GEL AND ACID 



After these mixtures had stood for twenty-four hours the control gelatin in tube 1 

 was perfectly solid. The mixtures in tubes 2, 3, 4, 5 and 6 were so solid that they could 

 be turned over, though on hard shaking they quivered; in tube 7 the gelatin flowed as 

 a viscid liquid; in tubes 8, 9, 10 and 11 the mixtures were entirely fluid. 



Table LXX brings out the same general truths for the addition 

 of acid to an otherwise solid, " neutral " gelatin gel. 



In interpreting the findings here described we would say that 

 under the influence of the added alkali or acid the " neutral " 



