4 GENERAL INTRODUCTION 



The development of knowledge in all branches of science, and 

 especially in chemistry, has been so rapid during the last fifty 

 years and the fields covered by this development have been so 

 varied that it is difficult for any individual to keep in touch with 

 the progress in branches of science outside his own specialty. 

 In spite of the facilities for the examination of the literature 

 given by Chemical Abstracts and such compendia as Beilstein's 

 Handbuch der Organischen Chemie, Richter's Lexikon, Ostwald's 

 Lehrbuch der AUgemeinen Chemie, Abegg's and Gmelin-Kraut's 

 Handbuch der Anorganischen Chemie and the English and 

 French Dictionaries of Chemistry, it often takes a great deal 

 of time to coordinate the knowledge available upon a single topic. 

 Consequently when men who have spent years in the study of 

 important subjects are willing to coordinate their knowledge 

 and present it in concise, readable form, they perform a service 

 of the highest value to their fellow chemists. 



It was with a clear recognition of the usefulness of reviews of 

 this character that a Committee of the American Chemical 

 Society recommended the publication of the two series of mono- 

 graphs under the auspices of the Society. 



Two rather distinct purposes are to be served by these mono- 

 graphs. The first purpose, whose fulfilment will probably render 

 to chemists in general the most important service, is to present 

 the knowledge available upon the chosen topic in a readable 

 form, intelligible to those whose activities may be along a wholly 

 different line. Many chemists fail to realize how closely their 

 investigations may be connected with other work which on the 

 surface appears far afield from their own. These monographs 

 will enable such men to form closer contact with the work of 

 chemists in other lines of research. The second purpose is to 

 promote research in the branch of science covered by the mono- 

 graph, by furnishing a well digested survey of the progress 

 already made in that field and by pointing out directions in 

 which investigation needs to be extended. To facilitate the 

 attainment of this purpose, it is intended to include extended 

 references to the literature, which will enable anyone interested 

 to follow up the subject in more detail. If the literature is so 

 voluminous that a complete bibliography is impracticable, a 

 critical selection will be made of those papers which are most 

 important. 



