Chemical and Physical Papers. 83 



slant escape of heat. It is fortunate that the majority of viands do 

 not require the evaporating process. 



It should be remembered that fireless cookers must be kept 

 clean. Vapors are given off and will condense more or less on the 

 walls, packing and lining, and these ought to be removable and 

 adapted to ready cleansing. This renovation need not be very fre- 

 quent, certainly no more often than is required in a refrigerator, 

 which employs the same sort of barrier to keep heat out that is 

 needed by the cooker to keep it in. The g^rms of putrefaction and 

 decay are destroyed more readily by the high temperature of our 

 cooker than by the ice-cold temperature of our refrigerator. 



In either utensil precautions are needed. The plea for economy 

 of heat in cooking will apply equally well to economy of ice in 

 using an ice-cream freezer. In most such freezers no care of this 

 is taken. The low temperature is secured by liquefaction of ice 

 and salt. The heat required for the solution is secured from the 

 surrounding vessels and their contents, which are thereby frozen. 

 There is seldom any care taken to surround the freezer by a non- 

 conductor, and therefore the heat required for melting the ice and 

 and salt is taken quite as much from the surrounding air as from 

 the cream. So more ice is used than needed, and the laborious 

 turning of the freezer is superfluous. 



A simple fireless cooker makes a pretty good freezer. First have 

 a vessel sufficient to contain the material to be frozen, then a 

 larger vessel into which the former will sit with a space of one and 

 one-half or two inches between the two, and this space is to be 

 packed with pounded ice and salt. Then put this comJbination into 

 the proper compartment of a fireless cooker and shut it up. The 

 cream will be frozen in a little longer time perhaps than the revolv- 

 ing freezer requires, but with half the expenditure of ice and salt, 

 and without further care or labor. When so frozen it will keep 

 there all day and longer without melting. 



