G8 Report op the Chemist of the " ' 



Introduction. 



Until five years ago there was little evidence at hand to show 

 whether there was any nniform relation between the amount of 

 fat in milk and the yield of cheese made from milk. Up to this 

 time it was almost universally held that, while fat in milk might 

 have some definite relation to butter yield, there could be no simi- 

 lar relation between milk-fat and cheese, because casein played 

 so important a part in cheese-yield. As a result of work done at 

 this Station, it has been established beyond question that there 

 is, within certain limits, a fairly definite and uniform relation 

 between milk-fat and cheese-yield, especially when we deal with 

 large quantities of milk. Up to 1895, our work dealt largely 

 with mixed factory milk, without extended study of detailed 

 variations that might exist in the milk of different herds of cows. 

 During the summer of 1895, we made a detailed study of the milk 

 of each of fifty different herds of cows, whose milk was used in 

 cheese-making at the factory of G. & F. H. Merry, of Verona, to 

 whose co-operation we are indebted for securing for us the sam- 

 ples of milk examined. 



The specific object of our investigation was to study the rela- 

 tion of fat to casein and to cheese-yield in the milk of different 

 herds, in order to ascertain whether this relation was uniform, 

 or whether it varied and, if it varied, whether regularly or irregu- 

 larly. 



In order to insure a clear understanding of what our investiga- 

 tion involves and of what its bearing is upon the daii-y industry 

 in relation to cheese-making, we will present briefly some of the 

 fundamental considerations relating to the question which forms 

 the subject of this bulletin. 



Formerly milk was universally paid for at cheese-factories 

 according to weight alone, on the supposition that all kinds of 

 normal milk were of equal value for cheese production. Investi- 

 gation showed that the cheese-producing power of milk varied 

 greatly, because the amount of cheese-making constituents in 

 milk was very different in different milks. It was found that, of 

 the several compounds contained in milk, only two are promi- 



