AUTHOR'S PREFACE 



IT has been the author's chief concern that this volume 

 should fulfil its own part in the programme set forth in 

 Dr. Rideal's General Preface. 



The leather, glue, and kindred trades have been for 

 many years recognized as chemical industries, but the great 

 development of colloid chemistry in the last few years has 

 given these trades a more definite status as such, and they 

 can now be placed in the category of applied physical 

 chemistry. The time is probably not far distant when 

 some knowledge of pure physical chemistry will be a first 

 essential to students, chemists, chemical engineers, and to 

 all engaged in these industries in supervision, administration, 

 or control. It is hoped that this volume will stimulate the 

 study of these industries from that standpoint. 



As the author has previously written upon one of the 

 industries involved herein ("The Manufacture of Leather " : 

 Constable & Co.), he has, rather inevitably, found it difficult 

 to avoid altogether his own phraseology. The changes of 

 a decade, however, together with the wider field and newer 

 view-point, have made possible a radical difference of 

 treatment. 



The author desires to acknowledge the help he has 

 received from the many books, essays, and researches which 

 are mentioned in the references at the end of each section, 

 especially to Procter's " Principles of leather Manufacture," 

 and also to thank Dr. Rideal for many useful suggestions. 

 The author would like also to acknowledge here his indebted- 

 ness (as well as that of the trade generally) to the work of 



