130 HEATING. 



r 



that exactly in the ratio that such union is complete, is the quan- 

 tity of heat increased. 



But we have not the means of obtaining this necessary sup- 

 porter in sufficient quantity, in a separate state, except at an ex- 

 pense which would render it incompatible with the purposes of 

 a furnace. Our only alternative then is to apply to the atmos- 

 phere, of which it forms a part, in order to satisfy our wants. 

 Had we to purchase this oxygen, we would, necessarily, be more 

 economical of its use, and inquire more respecting its application. 

 But, finding an abundant supply at hand, in the atmosphere, 

 and obtaining it without expense, we are careless of its use, and 

 unconscious of its value, and take no note of the largq 

 quantity of the noxious ingredients with which it is accompanied, 

 or loss sustained, by diminishing the supply; and hence, many 

 of the evils, such as bad apparatus, bad fuel, and bad furnaces, 

 might be easily remedied, were the properties of these gases fully 

 understood. 



The unions we have now to consider are those which take 

 place between the constituents of the coal and the atmospheric 

 air, namely, the hydrogen and carbon of the former, and the 

 oxygen of the latter. Dr. Ure calls the carbonaceous part of 

 coal, " the main heat-giving constituent." In this he must be 

 understood to include that portion of the carbon which forms 

 one of the constituents of the gases alluded to, and, although, 

 for the purposes of t\\e furTiace, so much value is set upon the 

 solid part — the coke — we must not, on that account, undervalue 

 the heat-giving properties of the gas. Indeed, the extent of 

 those powers is strikingly brought before us, by the fact, that for 

 every ton of bituminous coal no less than 10,000 cubic feet of 

 gas are obtained. 



When we consider the immense heating powers of such a 

 mass of flame as would be produced by 10,000 feet of gas, we 

 cannot resist the conclusion, that there must be something es- 

 sentially wrong in the mode of bringing it into action within a 

 furnace^ as compared to its well known efficacy in an argand 

 burner. That this is the fact, will appear manifest as we pro- 

 ceed. And one of our objects is to show how greater heat may 

 be obtained by the combustion of the volatile products of the 



