Page:Popular Science Monthly Volume 23.djvu/606

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wealthy and luxurious epicure, because I am convinced, not merely from theoretical considerations, but also from practical experiments, that all kinds of meat may be not merely as well roasted in a close oven as before an open fire, but that the close chamber, properly managed, produces better results in every respect than can possibly be obtained by roasting in the open air.

To obtain such results there must be no compromise, no concession to any false theory respecting a necessity for ventilation.

Many modern kitchen-ranges are fitted with such compromises in the shape of a ventilated roasting-oven, the action of which ventilation is purely and simply mischievous, excepting in the case of semi-putrid game or venison, which require to be carbonized and disinfected as well as cooked, and, of course, also demand the speedy removal of their noxious vapors.

Not so with fresh meats. There is nothing in the vapor of beef that can injure the flavor of beef, nor in the vapor of mutton that is damaging to mutton, and so on with the rest. But there is much that can, and does, actually improve them; or, more strictly speaking, prevents the deterioration to which they are liable when roasted before an open fire. I will endeavor to explain this.

Carefully-conducted experiments have demonstrated the general law that atmospheric air is a vacuum to the vapor of water and other similar vapors, while each particular vapor is a plenum to itself, though not to other vapors; or, otherwise stated, if a given space, at a given temperature, be filled with air, the quantity of aqueous vapor that it is capable of holding is the same as though this space contained no air at all, nor anything else. But this same space may contain a much smaller quantity of aqueous vapor, and yet be absolutely impenetrable to aqueous vapor, provided its temperature is unaltered.

Thus, if a bell-glass, filled with air under ordinary pressure, at the temperature of 100° Fahr., be placed over a dish of water at same temperature, a quantity of vapor, equal to one thirtieth (in round numbers) of the weight of the air, will rise into the bell-glass, and there remain diffused throughout. If there were less air, or no air at all (temperature remaining the same), the bell-glass would obtain and hold the same quantity of vapor.

If, instead of being filled with air, it contained at the outset only this one thirtieth of aqueous vapor, it would now be an impenetrable plenum, behaving like a solid to aqueous vapor—no more can be forced into it without raising its temperature.

But while thus charged with aqueous vapor, there would still be room for vapor of alcohol, or turpentine, or ether, or chloroform, etc. It would be a vacuum to these, though a plenum to itself. On the other hand, if the alcohol, turpentine, ether, or chloroform were allowed to evaporate into the bell-glass, a certain quantity of either of these vapors would presently enter it, and then this vapor would act