PREFACE. 



The analysis of dairy products has been the subject 

 of so much exact investigation within the last few 

 years, that most of the earlier processes have been 

 abandoned, since it has been shown that the data de- 

 rived from them are inaccurate. In the present work 

 we have had in view the object of providing not only 

 methods suitable for professional chemists, but also 

 such as may be safely employed by dairymen and 

 others unskilled in general analytical work. To aid in 

 securing uniformity, we have described some of the 

 published methods of the Association of Official 

 Agricultural Chemists, selecting those that we find to 

 be satisfactory. 



We have drawn freely from the valuable material 

 contributed to The Analyst and these references will 

 show how large a part of the advance in the analytical 

 practice in this field is, due to the industry and inge- 

 nuity of the members of the Society of Public Anal- 

 ysts. We have constructed a table, based on the form- 

 ula of Hehner and Richmond, arranged to suit the 

 method of calculating total solids from the fat and 

 specific gravity. Several other tables, not easily ac- 

 cessible, have been added, the insertion of which will 

 contribute to the usefulness of the work. 



yi5 Walnut St., Phila. H. L. 



July, 1891. W. B. 



