Ixvi Trans. Acad. Set. of St. Louis. 



Essai de statique chimique suggested a mathematical ground- 

 work for our doctrines of chemical action, but his effort was in a 

 sense premature . It remained for the Norwegians Guldberg and 

 Waage to follow up the idea, which they did in a treatise pub- 

 lished in 1867 with the title " iStudes sur les affinit^s chimi- 

 ques," in which problems of mass action and affinity are 

 handled systematically and in simple mathematical treatment. 

 Since that notable beginning many similar investigations have 

 been published and the journals teem with discussions on the 

 conditions of chemical equilibrium. Somewhat later than the 

 labors of Guldberg and Waage came the epoch-marking papers 

 of Gibbs and then the work of van't Hoff in which equili- 

 brium problems are more rigidly handled and in which the 

 many other applications of thermodynamics to chemical ques- 

 tions are pointed out. It may no longer be said that chemis- 

 try is " a science of the second rank." 



These advances are but a chapter in the new physical 

 chemistry, which includes much besides. The theory of the 

 independent action of the ions, the relation of this to ques- 

 tions of osmotic pressure, diffusion and electrical conductivity, 

 the relations of organic structure to optical activity and many 

 other chapters which might be mentioned, had I more time, 

 are all developments of the last fifty years. A word must be 

 said of the bearing of these discoveries in pure chemistry on 

 the new physiological or bio-chemistry, in the broad sense. 

 Where formerly we were obliged in the study of the animal 

 or vegetable cell to confine ourselves to questions of form we 

 now look to function as the thing of greatest importance. It 

 is not so much what the cell is, as what the cell does, and how 

 it does it, which claims our attention, and in the search for 

 light in this hidden field it is the new physical chemistry which 

 promises the greatest aid. Problems of fermentation and 

 enzymic activity are problems of chemical change and doubt- 

 less must find their solution by the same aids which have 

 been so helpful in other directions. The last fifty years have 

 witnessed practically the whole development of the doctrine 

 of cell ferments ; when we come together fifty years from 



