different kinds of Coal-gat Burners^ ^c. 239 



some may object to the use of gas in a bed-room, owing to 

 the production of carbonic acid ; but their fears on this ac- 

 count are groundless. Suppose that 40 feet of gas are con- 

 sumed, and that the whole of the products of combustion 

 escape into the apartment, these will, on an average, yield less 

 than their own bulk of carbonic acid gas, which, when diluted 

 with the air of the apartment, is too small to have any inju- 

 rious effect on the system. 



From what has been said, we are enabled also to ascertain 

 the comparative expense of the method some time ago pro- 

 posed, of heating apartments, such as churches, manufactories, 

 &c. by gas. This was done by burning the gas as it escaped 

 from a number of small apertures in a circular tube, which 

 was surrounded by a large box of sheet-iron, from which the 

 heated air was conveyed by tubes through the apartment. 



It has been already stated, that a pound of coal will eva- 

 porate about 14 lb. of water, were the whole heat taken up by 

 the water. But this is never done. 



Let us suppose that, in heating a large apartment by a 

 stove throwing in hot air, only one-half of the heat generated 

 by the combustion of coal is available, that is, that as much 

 heat is available as would evaporate only about 7 lb. of water 

 for the pound of coal ; then, to produce the same heat by gas, 

 as before stated, the comparative cost of the coal and of the 

 gas would be as one-fourth of a farthing and 2d., that is, in 

 the ratio of 1 to 82. 



It is evident from this that gas, as a means of warming 

 apartments, is by far too expensive to allow it to come into 

 use. 



That I am correct in what I say, is proved by the results of 

 experiments in which I have been lately engaged in heating 

 apartments by stoves. 



In one trial, I found that several large apartments were kept, 

 during winter, at the temperature of about 60°, during twelve 

 hours each day, by the daily consumpt of half a cwt. of coal. 

 Suppose this cost 10s. per ton, then the daily expense is only 3d. 

 But small coal, at from 58. to Gs. per ton, may be used for this 

 purpose, which would still farther dimmish the expease. The 



