are burners that give a very brilliant light with little gas, because the spare heat of the flame is used to heat the gas that is presently to be burnt. We warm our food on precisely the same principle. Very hot food is always unwholesome, but warm food always goes further and is more nourishing than cold.
Amount of Food.—A day's ration for a healthy man of average size, doing moderate work, has been reckoned as follows:—
| Oz. Avoirdupois. | |||
| 1. | Water | 4½ | |
| 2. | Albuminoids | 3 | |
| 3. | Fats, starch, sugar, etc. | 14 | |
| 4. | Salts | 1 | |
| ——— | |||
| 22½ | oz. |
For a woman, also working, the rations may be somewhat smaller, the proportions being the same, but the total about 3 oz. less.
This seems a small allowance, but when we remember that it is reckoned as dry food, and that food as we get it is always moist, generally containing half or rather more than half its weight of water, it appears that the food altogether should weigh about 40 ozs.
The quantity required varies, however, very much within the limits of health. Every man requires more food if he works hard, and less if he has no work to do. Even doing the same work no two men will eat exactly the same, and it is only possible to calculate by taking an average of a large number of eaters. Generally speaking, more food is required in cold weather and cold climates than in hot. But it is necessary that all these four classes of elements should be represented in our daily food, and in something like the above proportion. If we have too little of any one class we are sure to be ill, and if one class were to be quite left out we should die, even though we have plenty of other foods.
As to the water, there is not much to be said in addition to the remarks in the chapter on Beverages. By whatever name we call our beverages, the chief constituent of them is water, and were we given but one food we could exist longer on water alone than upon any other, except milk. In every food, even when artificially dried, there is a percentage of water, and taking foods one with another there is about half water. But the amount varies; in lettuce, 96 per cent, is water; in onions, 91; in lean meat, 75; in wheat, 14. Artificially dried substances are ready to take up water from the atmosphere, a fact of practical interest to the housewife, who will remember that oatmeal, maize-meal, biscuits, and the like, soon become flabby and moist if they are left in the open air. It is generally agreed that animals thrive better on moist food than on dry food with water.
