120 Chemistry. [Lecture 28. 



be occasionally removed for supplying the furnace 

 with fuel. 



The heat of the air furnace is in general in 

 proportion to the height of the vent; but when 

 the quantity of fuel is such that the vent cannot 

 be carried to a sufficient height, i. e. when the 

 chamber is extremely large, then other artificial 

 means of throwing in a blast of air are neces- 

 sary. Bellows are made use of for this purpose. 

 The improvement in the Carron works, by 

 throwing in the air through a cylinder, is very 

 .considerable. 



In blast furnaces the pipe of the bellows 

 should be a great deal larger than is common, 

 that the whole air may be thrown into the fire- 

 place at once. The eolipile, which is a hollow 

 ball of metal, filled with water, with a long pipe, 

 and which being heated sends forth a volume of 

 steam, has also been used for sending a stream 

 of air into the furnace Some have proposed 

 putting it into the ash-pit for this purpose, and 

 Dr. Lewis made the experiment, thinking that 

 the steam might more easily enter the fire, but 

 it did not answer ; for, in fact, it is not the 

 steam that increases the inflammability of the 

 fuel, but the air which it impels before it. Steam 

 itself extinguishes flame: a candle put into the 

 steam of boiling water is rapidly extinguished. 



It was before observed, that flame, when 

 mixed with air and agitated, produces the most 

 intense heat. The reason why the agitation of 



