PREFACE TO SECOND EDITION. 



THE science of dairying is constantly broadening. The 

 methods and art of manufacturing the best quality of butter 

 have gradually changed in conformity to the scientific princi- 

 ples involved, ard no manufacture of butter should now be 

 undertaken until a careful study has been made of the prin- 

 ciples governing the best methods of manufacture. 



The authors admit that, in our present state of knowledge 

 and experimental progress, it is in some instances difficult 

 to distinguish well established facts from those not universally 

 confirmed; hence it has been the object of the writers to give 

 only information supported by the preponderance of experi- 

 mental evidence. 



The first edition of this book has been, in a manner, well 

 received, indicating the work has met with general approval. 

 The second edition has been carefully revised, and two chapters, 

 one on "Creamery Refrigeration" and one on "Economic Oper- 

 ation of Creameries" have been added to meet an indicated 

 demand, and the authors hope that this will justify the use of 

 the book in our dairy schools, and also as a general reference 

 book for those engaged in dairy pursuits. 



The authors believe that the subject of dairying should no 

 longer be treated as a whole, and for this reason such subjects 

 as Testing Milk and its Products, Dairy Bacteriology, Cheese- 

 making, and Technology of Milk and its Products, have not 

 been treated comprehensively in this work. In connection 

 with the practical phase of butter-making the writers have 



