iv PREFACE TO SECOND EDITION 



first edition was published. The study of plant constituents is receiv- 

 ing greater attention and the papers dealing with the microscopical 

 studies are increasing in number. The examination of sublimates 

 obtained upon pyro-analysis of drugs is deserving of greater atten- 

 tion. During the past few years the author has had a great many 

 students follow this kind of work with a great deal of success. The 

 number of active principles which can be sublimed is increasing and 

 one is almost constrained to say that there are very few drugs which 

 do not yield a characteristic sublimate on igniting the drug. Further- 

 more, these sublimates can be further tested for identity so that 

 in applying this form of analysis it has a specific value in identify- 

 ing the drug and may be used as a criterion of its quality. For 

 these reasons this subject has been enlarged upon and a few illustra- 

 tions have been introduced. 



The general make-up of the book has been improved in several 

 particulars. The size of the printed page has been increased, thus 

 decreasing the number of pages and making it a more convenient 

 hand-book for the student. A most notable change has been in 

 the use of bold-face type to distinguish the titles of drugs discussed 

 and to indicate some of the more important features. These changes 

 will facilitate the use of the work by students and analysts. 



H. K. 

 January, 1920. 



