322 APPENDIX. 



burning of sulphur. And by what means such 

 intense Heat is produced, we are at a loss to de- 

 termine. 



Having spoken of the various methods of pro- 

 ducing Heat, we must next observe, that bodies 

 may be heated by communication. And several 

 experiments might be described to shew, that some 

 bodies will both communicate and receive Heat 

 more readily than, others. It is the same with re- 

 spect to Cold as to heat : for those bodies which 

 receive Heat most readily, most readily part with 

 it ; and if they do this, they must also suffer it to 

 pass through them (speaking of it as though it 

 were a body) from one substance to another, or 

 onduct it most readily, and vice versa. 



Iron is a good conductor of Heat : on the con- 

 trary, wood is one of the best non-conductors of 

 Heat known. That the former is a conductor, and' 

 the lattera non-conductor, of Heat, is evident from 

 the following simple experiment; if you take a 

 nail or a small piece of iron, and hold in the flame 

 of a fire or candle,, it will speedily become so hot 

 all over, as to oblige you to relinquish your hold ; 

 but if you take a small piece of wood and hold in 

 the flame, you may keep hold of it till it is nearly all 

 consumed by the fire, without being incommoded 

 by the heat of the wood. Hence heat passes with 

 case in iron, and with difficulty in wood. 



From the results of various experiments, Count 

 Rumjord * concludes that water , oil, mercury, 



and 



* In the Essays of this philosopher, very ingenious princi- 

 ples are applied to practical uses in the great art qf living. That 



my 



