I. CALORICS. 



This general division of the chemical arts receives con- 

 sideration from its principal subject, fuel, being the more 

 important of the two chief agents employed in these arts to 

 modify affinity, to break up existing, or to form new combina- 

 tions. We cannot conveniently divide the arts according as 

 they are acted upon by fuel or water, for these two prime agents 

 are often employed simultaneously in a single process. While, 

 therefore, the first classes of the arts are chiefly controlled by 

 the action of heat, they are not exclusively so ; and, again, 

 those which follow, although depending mainly on solution, 

 are likewise more or less influenced by temperature. 



1. Fuel and Furnaces. 



The various kinds of fuel employed in the arts may be most 

 conveniently divided into two groups : those consisting chiefly 

 of carbon, which burn without flame, and those containing both 

 carbon and hydrogen, which burn with flame. The division 

 is convenient, since flaming fuel is better adapted to certain 

 arts, and flameless fuel to others ; and in any particular art 

 requiring one of these species, it is rarely a matter of moment 

 which one of them is employed, the selection being usually 

 one of economy or convenience. The following are the varie- 

 ties of fuel : 



Flameless. Flaming. 



Anthracite, Bituminous coal. 



Coke, Wood, 



Charcoal. Rosin and Gas. 



To each of these may be added artificial fuels, which may be 

 made to burn either with or without flame. 



The furnaces employed in the arts are the boiler furnace, 

 or that emploj^ed to generate steam in a boiler, in which, 

 flaming fuel being generally used, the fire is maintained by a 

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