Preface to Eighteenth Edition. 



Each year that passes brings some valuable contributions to 

 our knowledge of the subjects treated in this book and a fre- 

 quent revision of it is therefore desirable. The present edition 

 contains descriptions of methods and apparatus that have stood 

 the test of actual use during the past few years; the new infor- 

 mation published since the; last revision of the book, has been 

 carefully sifted, and what was deemed of sufficient importance 

 has been incorporated in such detail as the scope of the book 

 permitted; many changes and additions suggested by the expe- 

 rience of the authors have also been introduced. 



The book has, in brief, been subjected to a renewed critical 

 examination and careful revision. Among thei new subjects dis- 

 cussed in this edition may be mentioned: Analysis of ice cream; 

 estimation of water in butter by thei Gray, Patrick, Irish, Dean, 

 and Wisconsin oven methods; the Marschall acid test; the McKay 

 and Michels' sampling tubes; milk and cream overrun; the Gott- 

 lieb method -of determining fat in milk; the Hart casein test; 

 standards for Babcock glassware, etc. The general adoption of 

 the book as a text or reference book in American dairy schools, 

 as well as the favorable reception which it has been accorded by 

 the dairy public in general, will, it is hoped, be further justified 

 by the present revision. 



Acknowledgment is due to the following parties for loan 

 of electrotypes, viz.: Creamery Pkg. Mfg. Co., Chicago, 111.; 

 Vermont Farm Machine Co., Bellows Falls, Vt. ; Dairy Specialty 

 Co., West Chester, Pa.; D. H. Burrell & Co., Little Falls, N. Y.; 

 De Laval Separator Co., New York City; Henry Tromner, Phila- 

 delphia, Pa.; Torsion Balance Co., New York City; Bausch & 

 Lomb Opt. Co., Eochester, N. Y.; J. G. Cherry, Cedar Eapids, 

 la.; Marschall Dairy Laboratory, Madison, Wis., and Interna- 

 tional Instrument Co., Cambridge, Mass. 



Madison, Wis., Jan. 4, 1908. 



