VI PREFACE 



exhaustively and may he forgiven if, instead, he elects to emphasize 

 those portions which are of special interest to him personally. He is 

 also generally excused from presenting an exhaustive bibliography. 



Most important of all, perhaps, lecturers are allowed to illustrate 

 their talks with numerous lantern slides, a feature which often greatly 

 increases the intelligibility of their presentation. This privilege is 

 reflected in the present case by a relatively high proportion of figures 

 and tables, which I hope will help in a similar way. In any case, the 

 illustrations form an integral part of the plan of the book. 



Although the topic is a specialized one, little previous knowledge 

 of it is assumed on the part of the reader. An elementary knowledge 

 of organic chemistry and, for the last two chapters, a slight ac- 

 quaintance with the notation of partial differentiation should be 

 sufficient. 



The author is grateful to the John Simon Guggenheim Foundation 

 for a fellowship that made the completion of this book possible, and 

 to friends and colleagues who read and criticized portions of the 

 manuscript. 



Casa Rosada W. C. B. 



May 1961 



