Br. Wall on Aitra^ion and Repulfton 455 



leaves a refinous farina, or fine oily dew, by 

 which the drops of water falling upon them will 

 be, for fome time, prevented fipm coming into 

 immediate contaft with the leaves j but will roll 

 oft, formed into fpheruks by the intrinfic attrac- 

 tion of their particles, as quickfilver rolls off 

 from wood, &c. 



The phenomena of quickfilver (thus cafuall/ 

 mentioned) will indeed greatly illuftrate this 

 fubjeflj for that fluid is very remarkable for the 

 flrong attradion of its particles inter Je. You 

 may argue, that mercury, falling upon wood or 

 marble, forms itfelf inro globules upon account 

 cf its repulfion frorn thofe fubftancesj but if it 

 be allowed to run upon other bodies, to which 

 it has a ftrong affinity, it difplays the fame pro- 

 perty in various degrees, according as that 

 affinity is more or lefs ftrong, more or lefs power- 

 ful to overcome the- attraction of its particles 

 inter Je., and to counteradt their difpofition to 

 form into globules. Thus mercury, poured upon 

 gold and fiiver, breaks at firft into globules i but 

 thcfe are almoil immediately attracted by thofe 

 metals, lofc their mobility, become flat, and, if 

 allowed to continue, amalgamate with the gold or 

 iilver: but, poured upon tin or copper, the mer- 

 cury feparates into globules in the farpe manner, 

 as if it was poured on wood or marble. Thefe 

 globules continue a long time perfed, but at 

 lad unite with the jin or copper j becaufc the 



attra<5tioa 



