E 3°3 J 



fered to cool, and then a globule of metaHic lead 

 wili be left upon the coal. If any iron is contained 

 in the lead ore, the lead, which is melted out of 

 it, is not of a metallic mining, but rather of a 

 black and uneven furface : a little borax muft in 

 this cafe be melted with it, and as foon as no bub- 

 ble is ieen to rife any longer from the metal into 

 the borax, the fire mull be difcontinued : when 

 the mafs is grown cold, the iron will; be found 

 fcorified with the borax, and the lead left pure, 

 and of a fhining colour. 



SECT. XXXVIiI. 



The borax does not fcorify the lead in thefe 

 fmall experiments, when it is pure: if the flame 

 is forced with violence on it, a bubbling will enfue, 

 refembling that which is obferved when borax 

 diflfolves a body melted with it, but when the fire 

 ceafes, the flag will be perfectly clear and tranfpa- 

 rent, and a quantity of very minute lead particles 

 will be feen fpread about in the borax, which have 

 been torn off from the mafs during the bubbling. 



S E C T. XXXIX. 



If fucn a lead ore (Sefh xxxvii.) is rich in filver, 

 this laft metal may like wife be difcovered by this 

 experiment -, becaufe, as the lead is volatile, it 

 may be forced off, and the filver remain. To effect 

 this, the lead, which is melted out of the ore, 

 mud be kept in conftant fufion with a flow heat, 

 that it may be confumed. This end willbefooner 

 obtained, and the lead part quicker, if, during 

 the fufion, the wind through the Blow-pipe is di- 

 rected immediately, though not forcibly, upon die 

 melted mefs itfelf, until it begins to cool, then the 

 rl/e muft be directed on it again. The lead a whkfi 



is 



