When vegetables, or other foods of ordinary temperature, are put into boiling water, the temperature of the water is lowered in proportion to the quantity and the temperature of the food thus introduced, and will not again boil until the mass of food shall have absorbed more heat from the fire.  The result of this is that the food is apt to become more or less water-soaked before the process of cooking begins.  This difficulty may be avoided by introducing but small quantities of the food at one time, so as not to greatly lower the temperature of the liquid, and then allowing the latter to boil between the introduction of each fresh supply, or by heating the food before adding it to the liquid.

EVAPORATION is another principle often overlooked in the cooking of food, and many a sauce or gravy is spoiled because the liquid, heated in a shallow pan, from which evaporation is rapid, loses so much in bulk that the amount of thickening requisite for the given quantity of fluid, and which, had less evaporation occurred, would have made it of the proper consistency, makes the sauce thick and unpalatable.  Evaporation is much less, in slow boiling, than in more rapid cooking.

MEASURING.—­One of the most important principles to be observed in the preparation of food for cooking, is accuracy in measuring.  Many an excellent recipe proves a failure simply from lack of care in this respect.  Measures are generally more convenient than weights, and are more commonly used.  The common kitchen cup, which holds a half pint, is the one usually taken as the standard; if any other size is used, the ingredients for the entire recipe should be measured by the same.  The following points should be observed in measuring:—­

1.  The teaspoons and tablespoons to be used in measuring, are the silver spoons in general use.

2.  Any material like flour, sugar, salt, that has been packed, should either be sifted or stirred up lightly before measuring.

3.  A cupful of dry material is measured level with the top of the cup, without being packed down.

4.  A cupful of liquid is all the cup will contain without running over.  Hold the cup in a saucer while measuring, to prevent spilling the liquid upon the floor or table.

COMPARATIVE TABLE OF WEIGHTS AND MEASURES.—­The following comparative table of weights and measurements will aid in estimating different materials:—­

One heaping tablespoonful of sugar weighs one ounce.

Two round tablespoonfuls of flour weigh one ounce.

Two cupfuls of granulated sugar weigh one pound.

Two cupfuls of meal weigh one pound.

Four cupfuls of sifted flour weigh one pound.

One pint of oatmeal, cracked wheat, or other coarse grains, weighs about one pound.

One pint of liquid weighs one pound.

One pint of meat chopped and packed solid weighs one pound.

Seven heaping tablespoonfuls of sugar = one cupful.