Processes in the Useful Arts. 



In mercury. Equal bulks. Equal weights. 



71,15 1,2181 



,017120 



165 



But the result will be the same if we suppose the capacity to be inva- 

 riable, and the quantity of matter to be increased, in the same proportion, 

 as the capacity increases by enlargement of volume ; and in order to faci- 

 litate our calculations we will proceed on this assumption. 

 We then obtain for the weight of the vapour 27,16743, and 



this reduced to the standard of water as 1 : ,8474. 23,02168 



For the weight of the azote, 1 147,11225, which reduced as 



1 : 2754, - - 315,91471365 



For the weight of the carbonic acid, 362,839644, which re- 

 duced as 1 : ,221, - 80,18756132 





419,12395497 

 Now, supposing it to be required to ascertain the quantity of heat going 

 to the chimney when steam of 225° or about equal to 38,2 inches of mer- 

 cury is employed, and when that of 265° or 71,15 inches is used, the air 

 in both cases, to escape at the same temperature as that of the steam in the 

 boiler. 



Then 419,12395497X40—16764,958 1988 lbs. of water raised 1°, or 

 1 lb. of water raised 16764°,958 1988-7-60000, = ,2780826 of a cubic foot 

 of water more converted into steam of 225° than of 265°, with a bushel of 

 coal. It will be observed that for the quantities of heat extricated during 

 combustion, I have here, as well as in my preceding observations, assumed 

 those given by Mr Dalton. 



5. On the increase of elasticity which obtains, when steam removed from 

 contact with its generating water is heated. 



According to Mr Ivory " the heat extricated from air when it under- 

 goes a given condensation, is equal to § of the diminution of temperature 

 required to produce the same condensation, the pressure being constant." 



Whence it seems to follow, that when a given expansion of volume ob- 

 tains the quantity of heat absorbed is equal to f of the increase of tempe- 

 rature required to produce that expansion. We shall suppose that a quan- 

 tity of heat represented by 960° is required to convert a cubic inch of 

 water into steam ; double the quantity of heat will of course vaporize 2 

 cubic inches of water, which will give about 3456 cubic inches of steam, 

 of the pressure of 30 inches of mercury. Now 960° will convert one inch 



