PKEFACE TO THE SECOND EDITION. 



WHEN we published, in April, 1874, the first edition of 

 this book, we were well aware that a process for the detec- 

 tion and determination of foreign fats in butter was urgently 

 needed, and that any method, based upon sound principles, 

 would be warmly welcomed. 



We are happy to state that we were not disappointed in 

 our expectations. One chemist after another critically and 

 carefully examined our process, and it was soon adopted, 

 with some modifications in its execution, in nearly every 

 laboratory all over the country in which articles of food are 

 examined. Butter analysis has, in fact, now been placed 

 upon as sound a basis as any branch of food analysis, and 

 the most difficult of problems is considered to be solved by 

 every one who has a voice in this matter. A few persons 

 have not been wanting, who from prejudice, or from other 

 causes, have struggled against the adoption of our process, 

 but they have, happily, been overruled. 



The composition of butter-fat has been closely studied 

 during the last few years, and many interesting facts, of 

 which we give a short account in the following pages, have 

 been brought to light. The subject is as yet by no means 

 exhausted, but as far as the practical part is concerned, we 

 feel confident that no great or important improvements of 

 the process will be introduced for some time to coine. 



