viii PREFACE TO THE SECOND EDITION 



seemed least essential. Furthermore, instruction in biological science 

 is now a part of the requirements of candidates for admission to the 

 various medical schools. 



At the request of many who have found the book of assistance I 

 have added an outline of those methods in the chemical examination 

 of urine and gastric contents which have seemed to me to be most essen- 

 tial in the making of diagnoses. In the tropics I have found the deter- 

 minations of total nitrogen and nitrogen eliminated as ammonia to be 

 exceedingly valuable in diagnosis. Methods for such determinations, 

 as elaborated by Assistant Surgeon E. W. Brown, U. S. Navy, of the 

 U. S. Naval Medical School, have proven satisfactory and have been 

 incorporated in this section which is to be found in the Appendix. 



Every effort has been made to keep the book within the limits of a 

 pocket manual. 



Owing to my absence from the United States I have to thank Dr. 

 Charles S-. Butler for correcting the proof. For the revision of the 

 index I am indebted to Mr. John P. Griest. 



E. R. S. 



