224 Diana's fret. [Book VI* 



is very tedious, and would require the fpace of a 

 month. 



This phenomenon feems to admit of explanation 

 precifely on the fame principle as the branching of 

 pure filver when pafling from it* fluid to its folid ftate. 

 The amalgam of filver and mercury is fpecifically 

 heavier than either of the rnetals in a feparate flate, 

 and their union muft confequently be attended with 

 contraction. The filver, therefore, being precipitated 

 on the furface of the mercury, in proportion as the 

 latter metal is difTolved by its fuperior attraction for 

 the acid, the mercury becomes furrounded with a 

 Crufl, the contraction of which forces out its fluid con- 

 tents ; the excrefcences thus produced being in their 

 turn covered with a cruft of amalgam, are again com- 

 prefled, and produce fmaller protuberances, and if the 

 experiment is properly conducted, the brittle amal- 

 gam of the metals a flumes a cryftallized appearance, 

 and the form of a thick bufli. In this experiment it 

 is neceflary that there fliould be not only as much mer- 

 cury as is fufficient to precipitate the filver, but be- 

 fides this a quantity remaining in its fluid (late, to unite 

 with the precipitated filver into an amalgam. 



Sulphur has a remarkably ftrong affinity with filver, 

 and forms with it a compound which has the appear- 

 ance and foftnefs of lead. This metal feems alfo ca- 

 pable of attracting fulphur from antimony. But 

 though filver has fo ftrong an attraction for fulphur, 

 gold has none, and this furniflbes a method of feparat- 

 ing thefe metals by fufion. 



With gold, filver forms a pale alloy, the green gold 

 of the jewellers and gold beaters. This mixture, 

 however, is not made without fome difficulty, on account 

 of the different fpecific gravities of the two metals. 

 It does not unite well with platina. It forms an alloy 



with 



