Analyfis of the Air. 301 



abforbs elaftick air vigorously : As may be 

 feen in many inftanccs under Experiment 95- 

 The Walton mineral, in which there is a 

 good quantity of fulphur, did, when Com- 

 pound Aqua-fortis was poufd 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 80 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 consideration fcems 

 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 5 but there arifing 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 

 off in the air, do by their attra&ion deftroy its 

 dafticity $ for in that Experiment burning 

 Mmftone greatly deftroy ed the air's elasticity ; 

 1 which 



