152 HEAT1^G. 



distillation of coal, at such temperatures that they may take fire 

 in its contact." If a number of jets of air be admitted into a 

 heated inflammable atmosphere, as the body of a furnace, its 

 combustion will be attained in such a way as to produce a great 

 increase of heat, and, as a necessary consequence, destroy the 

 smoke. 



In some of the large gardens of Europe, as will as in some 

 manufactories, attempts have been made to consume the smoke 

 or gases of the furnaces, by bringing them in contact with a body 

 of glowing incandescent fuel, producing a result the reverse of 

 what was expected, namely, the absorptioQ of heat by their 

 expansion and decomposition, instead of giving out heat by their 

 combustion. It is strange that this erroneous notion should be 

 persisted in, even at the present day, when any chemical work 

 of good authority would satisfy any one wishing for such knowl- 

 edge that decomposition^ not combustion, is the effect of a high 

 temperature being applied to hydro-carbon-gases; — that no 

 possible degree of heat can consume carton ; — that it is a well- 

 known property of both the varieties of carburetted hydrogen, 

 that they deposit charcoal, (carbon) virtually become smoke, 

 when heated ; — that the amount of carbon deposited is propor- 

 tioned to the increase of temperature, and that its combustion is 

 merely produced by, and is, in fact, its iinion with, oxygen, 

 which these smoke-burners take no care to provide.^^ 



* Numerous methods have been devised for burning smoke, and 

 patents have been issued for supposed inventions of this kind, showing 

 the want of chemical knowledge on this subject. One consists in hav- 

 ing a double set of fire-bars, so that when the fuel is red-hot, it is 

 thrown back on the innermost bars, and the smoke of the fresh coal in 

 front passing over this incandescent fuel, is supposed to be consumed in 

 its passage. Another proposes a sliding carriage for this purpose, 

 working on castors inside the furnace. Others of a sin ilar kind have 

 "!)een put forward, and aii on the same principle ; an manifesting the 

 same neglect or ignorance of chemistry, — for chemistry teaches us 

 that heat has nothing to do with the combustion of smoke beyond this, — 

 that a certain temperature is essential to the development of chemical 

 action between the combustible and the supporter, when they are 

 brought together. But producing heat is not producing air ; and decom 

 ^Hisition is not, in this respect, combustion. 



