PHYSICAL AND LITERARY. 32-9 



ged. Some ores, as they are taken from 

 the mine, tho' they appear pretty rich and 

 clean, yet will not readily diflTolve in the 

 fame menftrua which are fit to difTolve 

 the pure metals, until the ores are roaft- 

 «d, wafhed, and fmelted. The calces of 

 lead and tin will more ealily difTolve in 

 fpirit of vinegar, than the thin plates or 

 ihavings of the fame metals. 



VI. Some liquors which dilTolve feve- 

 ral different bodies, while they perforrn 

 ithe folutions, feem to a(5l in a different 

 nianner upon each body, require differen;: 

 helps, and difTolve different quantities 

 £)f each. 



This is very remarkable in the acfljon 

 of oil of vitriol upon iron arjd quick fil- 

 vei : To make oil of vitriol diffolve iron 

 fuccefs fully, it muft be diluted with a 

 quadruple quantity of water ; when the 

 clean filelngs are put into this liquor by- 

 degrees, there arifes a flrong ebullition 

 and e^fervefcence, with a confiderable heat 

 and thick fleams of a penetrating fulphu- 

 reous fmell, which are apt to kindle and 

 Vol. I. Tc make 



