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 animal and vegetable fats, but the slight variation may make a lot of difference in digestibility and palatability as well as in nutritive value, and it is a mistake to consider Oleomargarine, Butterine, Nut-Butter and other substitutes for butter "just as good" because a chemical analysis shows them to contain "almost" the same elements or compounds. These products may be good and legitimate if sold for what they are, but should never be allowed to be sold or served for what they are not, genuine butter.

SOLIDS NOT FAT TOTAL SOLIDS

MINERAL MATTER MILK SUGAR CASEIN & ALBUMIN BUTTER FAT

WATER

Composition of cow's milk

Casein and Albumin are the proteids or nitrogenous matters of the milk, in chemical composition and in food value much the same as the protein in beans and peas or in meat, or the white of eggs. Casein is present in much larger quantity than albumin and is distinguished from the latter by being precipitated by rennet, which has no effect on albumin. Casein may also be precipitated by acids, while it required boiling as well as acidity to throw the albumin out of solution.

Milk-Sugar is related to the vegetable sugars, glucose, cane sugar, etc., and remains in solution in the whey which separates out from the cheese-curd when milk is curdled with rennet or acids. The whey also contains the mineral matters or ash, which consists largely of phosphate of lime, of use to the young in building up bones.