162 Transactions of the Royal Society of Victoria. 



hour at 95° F., but little if any solvent action was observed 

 at the end of that time. 



It was thus made clear that the action of the mixed 

 ferment is almost completely checked in the presence of 

 hydrochloric acid, in the proportion of 1 part per 1000, and 

 to a considerable extent when the acid was present in the 

 strength of 1 to 5000. 



IX. For the purpose of discovering whether loss of power 

 was only temporary, or if the ferment had been permanently 

 injured ; the mixtures of starch and acid (Exps. IV., Y., 

 and VI.) were rendered alkaline, by the addition of 2 grains 

 of bicarbonate of soda to each, and again kept at 95° F. for 

 two hours. In that which had contained only ^qooo of the 

 acid, there was complete liquefaction, while in those which 

 had contained 50^00 and tu^o respectively, there was slight 

 breaking down of the clotty particles, but no great change. 

 In both of these, therefore, there had been permanent inj ury 

 to the ferment, though it did not seem to be completely 

 destroyed. 



X. For the purpose of discovering whether this destructioi. 

 would be effected by the presence of pepsin in the acid 

 mixture, the following experiment was carried out. Zymine 

 (1 grains) was heated for two hours at 95° F., in 40 c, ctrs. 

 of water, with 10 grains of Fairchild's scale pepsin, acidulated 

 to the strength of 1 in 1000. At the end of that time the 

 mixture was divided into two equal parts, each of which 

 was rendered slightly alkaline with bicarbonate of soda, and 

 heated again for an hour with 10 grains of pressed fibrin, 

 and the mucilage of 10 grains of starch respectively. It 

 was found that both the fibrin and the starch were almost 

 completely dissolved. This difi'erence from the experiment 

 before detailed (IX.), was due probably to the larger 

 amount of zymine present, 5 grains instead of 2. It was 

 made clear that the pepsin, as such, had not acted at all on 

 the zymine, though placed under very favourable conditions 

 for doing so. 



For the sake of completeness, the following counter- 

 experiment was tried : — 



XI. Five grains of pepsin were kept at 95° F. for 2 hours, 

 along with 5 grains of zymine and 2 grains of bicarbonate of 

 soda. Hydrochloric acid was then added in sufficient amount 



