Annlyji~> of the Air. 299 



more fubtile diflblvent fermentation: But we 



may obferve, that * :olent Sales, Spirits, and 

 fulphureous Oil, which are at the fame time 

 feparated from thefe fubftances, will not make 

 elaftick air. 



Experiment CXX. 



As elaftick air is thus generated by the force 

 of fire from thefe and many other fubftances, 

 to is the elafticity of the air greatly deftroyed 

 by fulphureous bodies. Sir Ifaac Newton 

 obferves, " That as light acts upon fulphur, 

 " fo, fince all action is mutual, fulphurs ought 

 " to act moft upon light/' And the fame 

 may be obferved of air and fulphur ; for by 

 Experiment 103. it is found that burning 

 fulphur, which is a very ftrongly attravting 

 fubftance, powerfully attracts and fixes the 

 elaftick panicles of air; fo that there muft 

 needs be a good quantity of unelaftick air- 

 particles in oil and flour of fulphur : The 

 firft of which is made by burning fulphur 

 under a bell, the other by fublimation: In 

 further confirmation of this it is obferved, 

 that Oleum Snlphuris per Campanam is with 

 more difficulty made in a dry than a moift 

 air j and I have found by Experiment pur- 



pofely 



