THE CHEMISTRY OF COOKERY. 589 



like a solid mass in resisting the entry of any more of its own kind, 

 while it would be freely pervious to the vapor of w r ater or that of the 

 other liquids. 



A practical example will further illustrate this. Some years ago I 

 was engaged in the distillation of paraffin-oil, and had a few thousand 

 gallons of the crude liquid in a still with a tall head and a rising con- 

 denser. In spite of severe firing, the distillation proceeded very slowly. 

 Then I threw into the still, just above the surface of the oil, a jet of 

 steam. The rate of distillation immediately increased with the same 

 firing, although the steam was of much lower temperature than the 

 boiling oil, and therefore w r asted much heat. The rationale of this 

 was that at first an atmosphere of oil-vapor stood over the oil, and 

 this was impervious to more oil-vapor, but, on sweeping this out and 

 replacing it by steam, tne atmosphere above the liquid oil was per- 

 meable by oil-vapor. This principle is largely applied in similar dis- 

 tillations. 



But I am exceeding my limits, and must, therefore, defer the direct 

 application of these principles to my next, though doubtless most of 

 my readers w r ill anticipate, or, in vulgar but expressive phrase, " see 

 what I am driving at." 



XI. 



Always keeping in view that the primary problem in roasting is to 

 raise the temperature throughout to the cooking heat with the smallest 

 possible degree of desiccation of the natural juices of the meat, and 

 applying to this problem the laws of vapor diffusion expounded in my 

 last, it is easy enough to understand the theoretical advantages of 

 roasting in a closed oven, the space within which speedily becomes 

 saturated with those particular vapors that resist further vaporization 

 of these juices. 



I say " theoretical," because I despair of practically convincing any 

 thorough-bred Englishman that baked meat is better than roasted meat 

 by any reasoning whatever. If, however, he is sufficiently " un-Eng- 

 lish " to test the question experimentally, he may possibly convince 

 himself. To do this fairly, a large joint of meat should be equally 

 divided, one half roasted in front of the fire, the other in a non-ven- 

 tilated oven over a little water by a cook who knows how to heat the 

 latter. This condition is essential, as some intelligence is demanded 

 in regulating the temperature of an oven, while any barbarian can 

 carry out the modern modification of the ordinary device of the sav- 

 age, who skewers a bit of meat, and holds this near enough to a fire to 

 make it frizzle. 



Having settled this question to my own satisfaction more than 

 twenty years ago, I now amuse myself occasionally by experimenting 

 upon others, and continually find that the most uncompromising theo- 

 retical haters of baked meat practically prefer it to orthodox roasted 

 meat, provided always that they eat it in ignorance. 



