PREFACE TO SECOND EDITION 



In preparing the second edition of this book the author lias 

 attempted to preserve the original character of the work. Much 

 material has been added, however, both in the text and labora- 

 tory section, and some older methods have been omitted. A 

 chapter on the portions of physical chemistry of most interest 

 in biology has been added, including more extended discussion 

 of colloids, and the material on enzymes has been considerably 

 extended. More material on the saliva, and muscle has been 

 included and a summary of the vitamines to the present date. 

 In the laboratory section the principal additions are the segre- 

 gation of the physicochemical material with the addition of vari- 

 ous simple but significant experiments, and the inclusion of 

 Folin 's methods for blood analysis and microchemical estimation 

 of certain constituents of the urine. 



The author wishes to express thanks for various suggestions 

 and corrections. 



C. J. V. P. 



Minneapolis, August, 1922. 



PREFACE TO FIRST EDITION 



My aim in writing this book has been to prepare an inter- 

 mediate text which would cover the general field of physiologi- 

 cal chemistry in such a way as to give students a familiarity 

 with compounds important from a biochemical viewpoint, and 

 to acquaint them with the fundamental processes which go on 

 in the animal body. I have attempted to avoid confusing the 

 beginner with lengthy discussions of debated points, but to set 

 forth as clearly as possible the present status of our knowledge. 

 The material is so chosen that the book may be used for inter- 

 mediate classes, or for advanced work if supplemented by lec- 

 tures. 



