l)r, Percival on AttraElion and Repiilfion, 451 



i-olls along a leaf, tv'hich has been wetted, its 

 brightnefs dilappears, and the green leaf, before 

 hardly difcernible, is now (it^n. clearly through 

 it. From thefe fads it is inferred, that the glo- 

 bule does not touch the plant; but that it is 

 fufpended at fome diftance, in the air, by the 

 force of a repulfive power; becaufe there could 

 not be any copious reflection of white light, 

 from its under furface, unlefs a real interval fub- 

 fifted between that furface and the plant. * This 

 hypothefis Recounts for the volubility of the 

 drop, and for its leaving no trace of moifture, 

 where it rolls. From the like realbning it hath 

 been concluded, that when a polifhed needle is 

 made to lie on water, it is not in cqntad v>/ith 

 that fluid, but forms, by repulfion, a bed, whofe 

 concavity is much larger than its own bulk. 

 Hence it is readily conceived, hovv the needle 

 fwims upon a liquid, lighter than itfelf ; fince 

 the quantity of water, difplaced by it, may be 

 equal to its weight. C^n it be phiiofophical, to 

 attribute fuch a plienomenon to thetcnacity of 

 water, or to the attradion fubfilling between its 

 particles ? 



IV. The attratflions ,2nd repulfions-^ between 

 thofe exhalations that are termed dew, and. cer- 

 tain fubftances expofed to them, are ftill more 

 remarkable, than the fads which have been 



• See Newton!s Optics, Query 29. Alfo Phyfical and 

 Literary Eff^ys vol. JI. p. 25. 



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