On the Ponuers of Steam, &c. Ill 



4thly. That if this liquor is converted into vapour, 

 it will previously absorb an additional quantity of 

 heat, which heat will again emerge, if it comes in 

 contact with any body which is capable of condensing 

 it into drops. 



It appears, therefore, that the presence of a certain 

 quantity of heat is essential to fluidity, as no body 

 can acquire that form, until ifeitas had time to draw 

 the necessary supply of heat from surrounding bodies; 

 and as this same quantity of heat immediately escapes 

 from the fluid, on its returning to its state of solidity. 

 This portion of heat seems likewise to exhaust all its 

 powers, in producing the arrangement of particles es- 

 sential to fluidity, for it does not appear to affect the 

 thermometer in the least, and hence has, by Dr. Black, 

 been termed Latent Heat. The presence of a still 

 larger quantity of heat is requisite for a state of va- 

 pour, as has been before remarked. 



The cold of Canada renders the use of stoves al- 

 most indispensible ; and the poorer sort, from the 

 want of fire-places, or to save fuel, arc frequently 

 obliged to dress all their victuals upon the stove. 

 Soon after my arrival in that country, I observed, 

 that whenever they wished to heat a kettle of water 

 very quickly, they threw two or three spoonfuls of 

 water upon the stove, and immediately placed the 

 kettle upon it, whilst it was bubbling up. Dr. 

 Black's theory had not penetrated into Canada, and 

 no one seemed even to have guessed at the reason of 

 lliis phenomenon ; nevertheless, the old women con- 



