BUYING AND SELLING ON FAT BASIS 213 
able food constituent of milk, and the quantity of this in 
any sample of milk bears a rather definite relation to 
the butter fat in the same milk, as the following figures 
of Dr. Van Slyke, of the Geneva (N. Y.) Experiment 
Station, show: 
Per cent of fat in milk. Per cent of casein in milk. 
3.0 2.1 
3°5 2.3 
4.0 256 
4.5 27 
5.0 2.9 
The other constituents of milk, while they vary ac- 
cording to the butter fat content, do not vary as much 
as the casein. 
It is fair to say that in point of food value, a quart 
of 5.5% milk is worth at least 50% more than a quart 
of 3.0%. In other words, when a consumer pays 9 
cents a quart for 5.5% milk he is paying no more for 
the actual amount of food he gets than when he pays 
6 cents a quart for 3% milk. 
It is as much a business proposition for consumers 
to consider the food value of milk as it is to consider 
the quality of cloth they buy. Milk should be bought 
under a guarantee as to its quality, which guarantee the 
consumer can enforce by having his milk tested oc- 
casionally for butter fat. The cream line on the bottle, 
upon which consumers rely more or less, is not a sure 
indication of the quality of the milk. 
A definite percentage of butter fat should also be 
guaranteed in cream. ‘This is especially important since 
the homogenizing of cream and the frequent use of 
viscogen by milk dealers makes it impossible to place 
