The Evolution of Chemistry. 145 



an exceptional process in nature. But electricity is now 

 well-nigh claiming universal domain as the force of forces, 

 and so old-fashioned catalysis seems almost bound to swallow 

 up all chemical activity. The number of substances that 

 unite with each other rapidly when third bodies are present 

 as impurities or otherwise, but that refuse to unite in a 

 state of absolute purity, is multiplying daily. As to how 

 such third bodies act in aiding the change is still in grave 

 doubt for the majority of such cases, but has been pretty 

 clearly traced in a few. In the manufacture of sulphuric 

 acid from sulphurous anhydride, nitric acid, though acting 

 as a go-between, is very far from a mere passive agent in the 

 change. During the molecular dance it suffers successive 

 decompositions and recompositions, always ending up in its 

 original state. If we had not discovered the part it really 

 plays in the matter it would be registered in the list of 

 catalytic bodies. 



When we turn to the organic world and undertake the 

 study of physiological chemistry and botany we find contact 

 action at every turn. Numerous ferments have been iso- 

 lated and studied by organic chemists, and with some of 

 them there can be little doubt that they act by successive 

 decompositions and recompositions of themselves. Much 

 of their apparently magical power depends upon their 

 ability to decompose water at normal temperatures. 



Let us but learn how to isolate such substances in paying 

 quantities and in such a form that they can accomplish the 

 same task as in the plant, and the growth in knowledge will 

 be marvelous for rapidity. "We have known several organic 

 ferments for a good many years. Pepsin and trypsin are 

 probably the two with which we are most familiar. To 

 solve the secret of their composition would be to gain a key 

 to the situation. For nearly thirty years chemist after 

 chemist has been baffled in attempting to do so. Not a 

 single ray of light has been thrown upon the problem. Un- 

 til we succeed in getting them in a pure state for analysis, 

 or in securing some decomposition product of them in such 

 a state, nothing can be done. A very faint glimmer was 

 for the first time discovered during the present year by your 

 essayist. A substance was isolated from pepsin "that bears a 

 constant relationship in quantity to its proteolytic power. 

 This is a very small result for thirty years of trial by scores 

 of chemists, but it must not be forgotten that the problem 

 is a big one, and the first gleam is always followed before 

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