[ 37 ] 



and probably alfo, from their mixture with one 

 another, the mod active come to be neutral 

 and innocent. — 



Did not the acid vigor of the trine, 



Roll'd from fo many thundring chimnies, tame 



The putrid fleams that overfwarm the Iky ; 



This cauftic venom would perhaps corrode 



Thofe tender cells that draw the vital air, 



In v^in with all their un&uous rills bedew'd *. 



It is in few inftances that the exhalations are 

 not expofed to the means of mixture ; and it is 

 but feldom, comparatively, that effects are pro- 

 duced upon human bodies, although in a par- 

 ticular manner immerfed in this vitiated atmo- 

 fphere. 



There are, however, fome impregnations in 

 the atmofphere, which daily experience mews 

 have considerable influence on our bodies for 

 though they may not fenfibly affect the more 

 robuft and Arong, they certainly do the weak and 

 delicate. With a view to investigate them more 

 particularly, the following experiments were 

 made in the beginning of Auguft, in the year 

 1769. 



For fome preceding weeks the air had been 

 generally warm and dry, and moftly free from 

 wind ; the evening on which I began to condenfe 

 the atmofpherical moifture was calm, and clos'd 

 a fine warm day ; the place where this moifture 

 was collected, was in a court about the centre of 

 Gracechurch-ftreet. 



I procured a large glafs globe perfectly clear* 

 on the outfide, into which I put a quantity of ice 



* Armllrong's Art of preferving Health, p. 51. 



D 3 and 



