»' 



:; 



Analjfis of the Air. 301 



abforbs elaftick air vigoroufly : As may be 

 fecn in many inflanccs under Experiment 95. 

 The Walton mineral, in which there is a 

 good quantity of fulphur, did, when Com- 

 pound Aqua-fort is was pour'd on it, in Ex- 

 periment 96, make a confiderable fermen- 

 tation, and abforb a great quantity of elaftick 

 air: But when the ferment was much in- 

 creafed, by adding an equal quantity of 

 water to the like mixture, then inftead of 

 abforbing 85 cubick inches as before, it 

 generated So cubick inches of air : So that 

 fermenting mixtures, which have fulphur in 

 them, do not always abforb, but fometimes 

 generate air : The reafon of which in the 

 Experiment now under confideration feems 

 to be this, viz, in the firft cafe a good quan- 

 tity of elaftick air was generated, by the 

 inteftine motion of the fermenting ingre- 

 dients j but there arifmg thence a thick, acid 

 fulphureous fume, this fume abforbed a 

 greater quantity of elaftick air than was be- 

 fore generated : And we find by Experiment 

 103 that the fulphureous particles which fly 

 ofFin the air, do by their attraction deftroy its 

 elafticity 5 for in that Experiment burning 

 Urimftonc greatly deftroy ed the air's elafticity; 

 j. which 





. 





I 







\ 11 



