iv Preface to Fifth Edition. 



tical dairy operator who wishes to understand the principles 

 and reasons underlying his art, numerous references to orig- 

 inal investigations have been added to aid the dairy inves- 

 tigator who wishes to work up the subject more thor- 

 oughly. 



My acknowledgments are due to the following for the 

 loan of illustrations: Wisconsin Agricultural Experiment 

 Station; Creamery Package Mfg. Co., Chicago, 111.; and A. H. 

 Reid, Philadelphia, Pa, 



H. L. RUSSELL. 

 UNrvEitsiTY OP WISCONSIN, 

 Madison, January, 1902. 



