ON THE ftEA* D£?ELOPE& IN COMBUSTION. !($ 



this. For my own part, I confess, I pay Tittle regard to 

 the experiments of which I am told, when I know they 

 are so negligently made; and assuredly I shall never waste 

 my time, in attempting to build theories on their results. 



In using the apparatus I have described, several pre- Complete 



cautions are necessary. In the first place it is obvious, that, """nbiistio*- 



, ... . • ' , /. , , requisite. 



when the object is to ascertain the quantity of heat de- 

 veloped in the Combustion of any inflammable substance, 

 it is indispensably necessary, so to arrange matters that 

 the combustion shall be complete. I have thought, that it 

 might be so considered, whenever the substance burned 

 leaves no residuum, and burns with a clear flame, without 

 smoke or smell. 



The least smell, particularly that peculiar to the in- Smell of t!he 

 flammable substance bnrned, is a certain indication, that st a™e'a proof 

 the combustion is imperfect. it is imperfect-. 



I had. long sought, before I was able to find to my 

 satisfaction, a mode of burning very volatile liquids, such 

 as alcohol and ether: but 1 have at length discovered it, 

 as will soon appear. I have frequently succeeded in 

 burning highly .rectified sulphuric ether, without the least 

 smell of ether being diffused through the room; and it 

 was in these instances alone, that I considered the experi- 

 ments as accurate. » 



As to wood I have found a very simple method of Method of 

 burning it completely, without the least appearance of ^p^eiy** 

 smoke or smell. I got a joiner to plane me shavings 

 about half an inch wide> a tenth of a line thick, and six 

 inches long: and holding these in the hand or with pliers, 

 elevated at an angle of 45° or thereabout, and with the 

 edges perpendicular, they burned like a match, with a very 

 clear flame. 



The slip of wood that burns being very thin, and placed 

 between two flat flames, which press on it closely, it is 

 exposed to the action of so strong a heat, that it burns 

 perfectly and entirely. 



If the shavings employed be too thick, a portion of the 

 charcoal of the wood remains; particularly if it be oak, or 

 any other wood of slow and difficult combustion : and in 

 this case the experiments are defective. But if the shaving* 



b- 



