5 88 THE POPULAR SCIENCE MONTHLY. 



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 man- 

 aged, 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, pre- 

 vents 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 al- 

 lowed to evaporate into the bell-glass, a certain quantity of either of 

 these vapors would presently enter it, and then this vapor would act 



