CHEMICAL COMPOSITION OF FOOD-FISHES. 
819 
of food. The proportions of these ingredients are determined by thr 
somewhat complicated methods of chemical analysis followed in tho 
laboratory, but our everyday handling of food materials often involves 
processes, though crude ones, of analysis. 
We let milk stand; the globules of fat rise in cream, still mingled, 
however, with water, protein, carbohydrates, and mineral salts. To 
separate the other ingredients from the fat the cream is churned. The 
more perfect this separation — i . e ., the more accurate the analysis— the 
more wholesome will be the butter. Put a little rennet in the skimmed 
milk, and the casein, called in chemical language an albuminoid or 
protein compound, will be curdled, and may be freed from the bulk 
of the water, sugar, and other ingredients by the cheese press, as is 
done in making cheese. To separate milk-sugar, a carbohydrate, from 
the whey is a simple matter. One may see it done by the Swiss shep- 
herds in their Alpine huts. But farmers find it more profitable to put 
it in the pig-pen, the occupants of which are endowed with the happy 
faculty of transforming sugar, starch, and other carbohydrates of their 
food into the fat of pork. 
The New England boy who on cold winter mornings goes to the barn 
to feed the cattle and solaces himself by taking grain from the wheat bin 
and chew 7 in g it into what he calls “wheat gum” makes, unknowingly, 
a rough sort of analysis of the wheat. With the crushing of the grain 
and the action of the saliva in his mouth the starch, sugar, and other 
carbohydrates are separated. Some of the fat— i. e . , oil — is also removed, 
and finds its way with the carbohydrates into the stomach. The tena- 
cious gluten, which contains the albuminoids or protein and consti- 
tutes what he calls gum, is left. When, in the natural order of events, 
the cows are cared for and the gum is swallowed, its albuminoids enter 
upon a round of transformation in the boy’s body, in the course of 
which they are changed to other forms of protein, such as albumen of 
blood or myosin of muscle, or are converted into fat, or are consumed 
with the oil and sugar and starch to yield heat to keep his body warm 
and give him muscular strength for his work or play. 
There is, unfortunately, a little confusion of terms in the usages of 
different writers on these subjects. Thus the words protein, proteids, 
and albuminoids are all applied to what we have here called the protein 
compounds. The term albuminoid, albumen-like, comes from albumen, 
which is best known in the form of white of eggs, a typical albuminoid 
compound. The term proteids is applied by some writers to albumin- 
oids and by others to very different classes of materials. The fats are 
sometimes spoken of as hydrocarbons, but this use of the latter term is 
very incorrect. 
These different classes of nutrients in food, to wit, protein, fats, carbo- 
hydrates, and mineral matters have different uses in nutrition. Muscle, 
tendon, and bone are formed from the protein compounds. These are 
sometimes called tlesh-formers, because they make flesh. Their chief use 
