222 THE POPULAR SCIENCE MONTHLY. 



temperature than 212 by any amount of violent boiling, the popular 

 distinction between " simmering " and boiling, which is so obstinately 

 maintained as a kitchen superstition, is demolished. 



The experiment described in my last showed that immediately the 

 bubbles of steam reach the surface of the water and break there that 

 is, when simmering commences the thermometer reaches the boiling- 

 point, and that however violently the boiling may afterward occur, 

 the thermometer rises no higher. Therefore, as a medium for heating 

 the substance to be cooked, simmering water is just as effective as 

 " walloping " water. There are exceptional operations of cookery, to 

 be described hereafter, wherein useful mechanical work is done by 

 violent boiling ; but in all ordinary cookery, simmering is just as 

 effective. The heat that is applied to do more than the smallest de- 

 gree of simmering is simply wasted in converting water into useless 

 steam. The amount of such waste may be easily estimated. To raise 

 a given quantity of water from the freezing to the boiling point de- 

 mands an amount of heat represented by 180 in Fahrenheit's ther- 

 mometer, or 100 Centigrade. To convert this into steam, 990 Fahr. 

 or 500 Cent, is necessary just five and a half times as much. 



On a properly-constructed hot-plate or sand-bath, a dozen sauce- 

 pans may be kept at the true cooking temperature, with an expendi- 

 ture of fuel commonly employed in England to " boil " one saucepan. 

 In the great majority of so-called boiling operations, even simmering 

 is unnecessary. Not only is a " boiled leg of mutton " not itself boiled, 

 but even the water in which it is cooked should not be kept boiling, as 

 we shall presently see. 



In order to illustrate some of the changes which take place in the 

 cooking of animal food, I will first take the simple case of cooking an 

 egg by means of hot water. These changes are in this case easily visible 

 and very simple, although the egg itself contains all the materials of a 

 complete animal. Bones, muscles, viscera, brain, nerves, and feathers 

 of the chicken all are produced within the shell, nothing being added, 

 and little or nothing taken away. 



When we open a raw egg, we find, enveloped in a stoutish mem- 

 brane, a quantity of glairy, slimy, viscous, colorless fluid, which, as 

 everybody now knows, is called albumen, a Latin translation of its 

 common name, " the icliUe." Within the white of the egg is the yolk, 

 largely composed of that same albumen, but with other constituents 

 added notably a peculiar oil. At present I will only consider the 

 changes which cookery effects on the main constituent of the egg, 

 merely adding that this same albumen is one of the most important, if 

 not the one most important, material of animal food, and is repre- 

 sented by a corresponding nutritious constituent in vegetables. 



We all know that when an egg has been immersed during a few 

 minutes in boiling water, the colorless, slimy liquid is converted into 

 the white solid to which it owes its name. This coagulation of albu- 



