Page:Popular Science Monthly Volume 23.djvu/528

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THE POPULAR SCIENCE MONTHLY.

meat, soup is merely a luxury, not a necessary element of complete dietary.

What we call boiled meat, as a boiled leg of mutton or round of beef, is an intermediate preparation. The heat is here communicated by water and the juices partially retained.

Note.—A correspondent tells me that he has tried the method of cooking eggs which I recommended, and he states that his eggs "were not cooked at all." From what I can learn by his letter, he omitted to attend to the quantity of water I named, viz., about a pint.

As this is of essential importance, I should perhaps have stated it with some emphasis. More than a pint of water should be used rather than less, as upon the quantity of water depends the retention of the heat. If the quantity of water is smaller, it should be kept boiling about half a minute before setting aside.

 
VIII.

The application of the principles already expounded to the processes of grilling and roasting is simple enough. As the meat is to be stewed in its own juices, it is evident that these juices must be retained as completely as possible, and that in order to succeed in this we have to struggle with the evaporating energy of the "dry heat" which effects the cookery.

It should be clearly understood that the so-called "dry heat" may be communicated by convection or by radiation, or both. When water is the heating medium, there is convection only, i. e., heating by actual contact with the heated body. In roasting and grilling there is also some convection-heating due to the hot air which actually touches the meat; but this is a very small element of efficiency, the work being chiefly done, when well done, by the heat which is radiated from the fire directly to the surface of the meat, and which, in the case of roasting in front of a fire, passes through the intervening air with very little heating effect thereon.

I am not perpetrating any far-fetched pedantry in pointing out this difference, as will be understood at once by supposing that a beefsteak should be cooked by suspending it in a chamber filled with hot dry air. Such air is actively thirsting for the vapor of water, and will take into itself, from every humid substance it touches, a quantity proportionate to its temperature. The steak receiving its heat by convection, i. e., the heat conveyed by such hot air, and communicated by contact, would be desiccated, but not cooked.

This distinction is so important that I will illustrate it still further, my chief justification for such insistence being that even Rumford himself evidently failed to understand it, and it has been generally misunderstood or neglected.

Let us suppose the hot air used for convection cooking to be at the cooking-point, as the hot water in stewing should be, what will follow its application to the meat? Evaporation of the water in the juices, and with that evaporation a lowering of temperature at the surface of