^3 ■ Experiments and Ohferijati'qnS) . j 



that arife from tliefe moill and ^aelt^rjcd fitua^kns. . Hail: too 

 cannot be afcribed to^any othqr caiife ; if k owed its origin, to 

 cold only, it would l:?q,nw)r^ prevalent in winter than in fummer; 

 it would, like,fli9,wer& ojEar^in, extend over. large traOs of country; 

 and it would fall from -much^ greater heights than it generally 

 does. But hail, like fro^ft, is often confined , to a very narrov/ 

 region, prevails in the warmeft weather, g.nd in long clofe vallies 

 at a diftance from the fea, more than in the. open country or 

 near the ocean. Thus France and Italy are extremely incom-. 

 moded by hail-ftorms ; in England they are very rare. All 

 thefe phenomena correfpond with the theory laid down j in 

 fummer are the greateft exhalations of volatile alkalies. Thefe 

 arc more like to arife, and form their union with the aerial acids 

 in vallies where the air is moft comprefTed ; in thefe fituations 

 they frequendy meet with thofe moift clouds that diffolve them 

 fu'ddenly, and afford the water that is by the folution of the 

 falts converted into hail. The fait compofed of an acid and a 

 volatile alkali, as fal amoniac, difTplves with great rapidity when 

 it comes in contaB: widi water, and generates a great degree of 

 cold ; while common fait diflblves much flower, and does not 

 generate fo much cold by 1 8 degrees in its folution ; for 

 which (among other reafons) hail prevails lefs near the fea than 

 at a diftance from it. That fuch falts are formed in the air 

 is farther proved from the experiments of Margraff and 

 DoQor Ratty, who both obtain a bitter fait from fnow and rain 



