Fats also have the great advantage, like the starches, of keeping well for long periods, especially after they have been melted and sterilized by boiling, or "rendering," as in the case of lard, or have had moderate amounts of salt added to them, as in butter.
If you were obliged to pick out a ration which would keep you alive, give you working power, and fit into the smallest possible bulk, you would take a protein, a sugar, and a fat in about equal amounts.

Indeed, the German emergency field-ration, intended to keep soldiers in the field for three or four days without their baggage-wagons, or cook-trains, is made up of bacon, pea-meal, and chocolate.

A small packet of these, which weighs only a little over two pounds, and which can be slipped into the knapsack, will, with plenty of water, keep a soldier in fighting trim for three days.
Butter.

The most useful and wholesome single fat is the one which is in greatest demand--butter.

This, as we have seen, is the churned and concentrated fat of milk, to which a little salt has been added to keep the milk-acid (_lactic acid_) which cannot be entirely washed out of it, from "turning it sour" or rancid.