106 .Evaptr Alien produces Cold. [Book II. 



an elaftic fluid. If a thermometer is immerfed in 

 ipirit of wine, in water, or in any fluid that eafily eva- 

 porates, and is afterwards taken out and fufpended in 

 the air, the thermometer will fink two or three degrees, 

 though the temperature of the air and water mould be 

 exactly the fame j the fadt is, the linall quantity of 

 fluid which remains on the bulb of the thermometer 

 is carried off in vapour, and in that cafe the mercury 

 within the thermometer is deprived of a certain por- 

 tion of its latent fire. If the thermometer is repeat- 

 edly dipped in the fluid, the cold which is produced 

 will be confiderable. If ether, which is a very vo- 

 latile fluid, is applied to any part of our bodies, cold 

 is immediately produced ; and on the fame principle, 

 a man may be frozen to death in very warm weather, 

 by expofing him to continued evaporation ; which 

 may be effected by throwing repeatedly upon his body 

 a. quantity of ether, of fpirit of wine, or of any other 

 fluid which is eafily evaporable. It is a common prac- 

 tice in China to cool wine or other liquors by wrap- 

 ping the bottle in a wet doth, and hanging it up in 

 the fun j the water in the cloth" is gradually convert- 

 ed into vapour, to form which the liquor in the bottle 

 is deprived of its latent fire. The celebrated Muf- 

 chenbroek was aftonifhed at the freezing of a wet 

 cloth which was hung up to dry, when there was nt> 

 appearance of froft in the atmofphere : the folution of 

 the difficulty is, the temperature of the air at the time 

 rnuft have been within fome degrees of froft, and the 

 temperature of the cloth was fuddenly reduced to the 

 freezing point by the lofs of a part of its heat from 

 evaporation. 



Let it be remembered, that in all thefe inftanoes 

 there is an evident acceflion or increafe of the matter 

 of fire thrown into the bodies which are rendered 



fluid, 



