57. Potatoes.—The potato contains about three-quarters of its weight of water. The solid matter is principally starch; the saline substances it contains, however, render it valuable as a fresh vegetable; the addition of a few pounds of potatoes weekly to the diet of sailors, &c., is most effectual in preventing scurvy; the potato also contains a peculiar substance taste; this is in great part driven off by the heat employed in cooking; some, however, remains in the water in which potatoes are boiled, giving it a disagreeable taste and smell; consequently in making an Irish stew, or soup in which potatoes are used, it is desirable to boil them by themselves in the first place and throw away the water in which they are boiled. Potatoes should be cooked with their skins on, except when baked under meat; for if peeled before boiling, there is great waste, as well as considerable loss of time; they can also be cooked to a much greater degree of perfection when boiled unpeeled. Many kinds of potatoes are much better steamed than boiled, and there is less risk of their being badly cooked. It should be borne in mind, however, that, as the condensed steam runs back into the saucepan underneath, the water becomes contaminated, and imparts an unpleasant taste to any food boiled in it.