VI PREFACE 



On this account certain chapters of the book especially, 

 e.g., those on the principles of organic chemistry, have been 

 written in a more elementary manner than would be called 

 for by the pure chemist. On the other hand, the methods 

 of experiment and research -employed in bacteriological and 

 enzyme chemistry have been illustrated in some detail by 

 typical examples. 



The endeavour has also been made to keep the style in- 

 teresting and readable, without sacrificing scientific accuracy, 

 How far this object has been attained it will be for the reader 

 to judge. 



It is impossible for any one scientific worker to be a 

 specialist in more than, at most, a very few branches of 

 study. The author has been fortunate in obtaining valuable 

 assistance in the writing of this book from many of his 

 scientific colleagues. In particular he would gratefully 

 acknowledge the help which he has received from Professor 

 Adrian Brown of the University of Birmingham, Dr. A. Harden 

 of the Lister Institute, Dr. E. J. Eussell of the Eothamsted 

 Experimental Station, Dr. H. H. Mann, Chemist to the 

 Indian Tea Association, and Mr. S. H. Davies, Chemist to 

 Messrs. Eowntree and Co. 



Other references will be found in the body of the book, 

 or in the short bibhography at the end. The latter, while 

 comprising only important text-books, and original papers 

 of fundamental interest, will, it is hoped, enable the student 

 to continue his reading, and to follow up the subject in any 

 direction, by means of the fuller bibhographies in the works 

 cited. 



In conclusion it is only right to mention the great assistance 

 the author has received from his wife, who has acted as his 

 amanuensis, and to whom this book is dedicated. 



G. J. F. 

 January, 1911. 



