PREFACE TO THIRD EDITION 



This book is intended as a concise manual of the chemical 

 examinations of commercial milk and milk-products. Only 

 processes of practical utility are described. Nothing has been 

 said concerning the food- value of milk or its products. Much 

 text has been used from the second edition of "Select Methods 

 in Food Analysis." I am under obligation to P. Blakiston's 

 Son & Company for permission to use this matter and also 

 for the loan of several cuts. 



Since the second edition appeared much change has occurred 

 in some departments of milk analysis, while others have under- 

 gone but little modification. The most noticeable changes 

 are in regard to the detection of preservatives. Several recently 

 discovered and useful tests for formaldehyde will be found in 

 the following pages, also convenient tests for abrastol and ben- 

 zoates. Cochran's method for fat determination will be found 

 to be a useful addition to the facilities for examining condensed 

 milk and infant foods. 



Unless otherwise stated all degrees are centigrade and all 

 readings of scale and arc are positive. 



I desire to place again on record a protest as to the state- 

 ments occasionally made concerning the rapid process for 

 determining fat in milk by means of the mixture of amyl 

 alcohol and hydrochloric acid. Much misrepresentation has 

 been current in regard to it. A letter is in my possession which 

 shows that some American chemists have misled foreign chem- 

 ists in regard to the priority of discovery. The Gerber method 



