42 ANSWERS to the OBJECTIONS 



ledges, that he had alfo been ftruck with that appearance, which 

 he thought inexplicable by the ordinary laws of evaporation and 

 condenfation. But, fays he, it is not to be admitted as <" fadt 

 to prove the fuppofed propofition. Why ? Becaufe it doc; not 

 belong to hygrology, but to phyfiology. 



I SHOULD have been at a lofs what to have replied to this ob- 

 jecflion, had not M. de Luc, in fome meafure, explained him- 

 felf in the next fentence ; where he fays, that the vapours 

 which are manifefled in this cafe, do not proceed from the eva- 

 poration of water contained in the lungs. Here, then, it is 

 evident, that M. de Luc leaves the fubjedt in hand, the conden- 

 fation of the breath, to enquire after the caufe of its humi- 

 dity. But whatever be the caufe of this aqueous vapour in the 

 breath, there is certainly no queftion about its eff'edl ; that is, 

 the humidity of the warm expired air, which is to be mixed 

 with the atmofphere, and there to produce mift. I do not, there- 

 fore, fee how any argument can be founded upon this fuppofed 

 operation of the lungs, whatever it be, any more than upon, 

 that of the heart, the liver or the kidneys. In our meteorolo- 

 gical enquiry, we furely are no ways concerned about the com- 

 pofition or decompofitlon of water ; a fubjedl of chemical en- 

 quiry : We only want to explain the condenfation of that hu- 

 midity which is on all hands allowed to be in the breath. 



The queftion which, in. this cafe, fhould, according to the 

 rules of fcience, have been either acknowledged or denied, was 

 this, Does the moift air, expired inbreathing, form a condenfa- 

 tion of water, in being mixed with cooler air fufEciently fatu- 

 rated with humidity ? M. de Luc has evaded making any di- 

 redl anfwer to that queftion, in propofing to develope the fub- 

 je<5l upon fbme other occafion. T his may have fuited the conr 

 veniency of our author, who was bufy in forming a meteoro- 

 logical theory very different from that which I had propofed ; 

 but he had undertaken to difprove my propofition, with regard 

 to the condenfation of vapour ; and this vifible condenfation of 



the 



