PREFATORY NOTE TO AMERICAN 

 EDITION. 



THE advance of medicine is so dependent upon 

 progress in the fundamental sciences of physics, chem- 

 istry, and biology that he who will keep abreast of 

 modern conceptions in physiology and pathology is 

 compelled to be more or less conversant with theory 

 and practice in the basal subjects. When one con- 

 siders the phenomenal development in recent years, 

 through the work especially of Willard Gibbs, van't Hoff, 

 and Arrhenius, in the domain of what is designated 

 physical chemistry, it is not surprising that attempts 

 should have been made to apply the new knowledge 

 gained to the clearing up of some of the problems 

 which confront the physician. While the application 

 of stoichiometrical methods in medicine and biology 

 has led and is leading to fruitful results, it is from 

 the utilization of the principles of the other great branch 

 of physical chemistry, that which deals with energy- 

 relations in chemical processes, that most is to be 

 hoped; that many of the medical conceptions of the 

 future are to be colored by the ideas of thermochem- 

 istry, electrochemistry, chemical kinetics, and chemical 

 dynamics even those of us who are entirely untrained 

 in these sciences are compelled to admit. The work 

 already done on reaction- velocity, catalysis, -equilibrium, 

 viscosity, osmotic pressure, and electrolytic dissocia- 



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