Chemical and Physical Papers. 81 



ECONOMY OF HEAT IN COOKING. 



By J. T. LovEWELL, Ph. D., Topeka. 



TT is well known that the potential energy of fuel, when applied 

 ^ to steam-engines, is largely dissipated without mechanical or 

 other useful effect. It is none the less true when applied to cook- 

 ing that heat goes out into the flues or produces uncomfortable 

 temperatures in our kitchens, while but a small percentage of it is 

 actually employed in those preparations of food we term cooking. 



In most of these operations the essential thing is the mainten- 

 ance of requisite temperature long enough to secure those chemical 

 changes and that breaking up of starchy or proteid constituents 

 which renders the food palatable and easy to digest. In the great 

 majority of culinary processes there is no necessity for evaporation 

 with the consequent loss of heat, nor for the access of air. As or- 

 dinarily conducted there is often a great amount of vapor set free, 

 mixed with other gases with unpleasant odors. Then there is the 

 discomfort of having this vapor condense on windows and fur- 

 niture and contaminate the air we must breathe. To avoid this 

 waste of heat and its unpleasant results, we have only to raise our 

 cooking vessels and their contents to the proper temperature and 

 then put them into an enclosure where the heat cannot escape. It 

 is the continuance of heat and not its constant addition which ef- 

 fects the cooking. 



Our problem is to prevent the escape of heat; and while the so- 

 lution is not absolute, we can secure practical results without much 

 difficulty. Of the modes of heat transference, radiation, convec- 

 tion and conduction, we shall need to consider chiefly the latter in 

 making an enclosure imi^ervious to heat. Metals, well known as 

 the best conductors, will therefore be discarded from our list of 

 available materials. Of other solids, various kinds of wood, stone 

 and manufactured products remain to be chosen from, and their 

 merit is chiefly determined by the amount of air-spaces they in- 

 clude. The poorest conductors are liquids and gases, but the former 

 are obviously not available, and we are therefore led to choose a 

 substance filled with air-spaces so small that convection need not 

 be considered, and have practically a gaseous enclosure for retain- 

 ing heat. 



We may take wood where the air-cells are formed in the natural 

 growth of plants, or we may take asbestos or many other silicates 

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