VOt. Xn.] PHILOSOPHICAL TRANSACTIONS. 457 



melted. If any dross or filth be in the melting-pot, they throw in some tincal, 

 which collects the dross together, that it may be separated from it. These 

 melting-pots are never burned, but only dried, and will last a whole day, if they 

 be not suffered to cool : but if they once cool, they infallibly crack. 



The next is the almond furnace or sweep. Here are separated all sorts of 

 metals from cinders, parts of melting-pots, tests, brick, and all other harder 

 bodies, which must be first beaten into small pieces with a hammer, and an iron 

 plate. Those which stick but superficially to the silver, they wash off thus : 

 they have a wooden round instrument, 2 feet wide, somewhat hollow in the 

 middle, with a handle on each side. On this they put the materials, and hold 

 them in a tub of water below the surface, and so waving it to and fro, all the 

 lighter and looser matter is separated from the metal. 



The furnace is 6 feet high, 4 feet wide, and 2 feet thick. It is made of 

 brick, having a hole in the middle of the top, 8 inches over, growing narrower 

 towards the bottom, where on the fore part it ends in a small hole, encompassed 

 with a semicircle of iron, to keep the melted metal. About the middle of the 

 back is another hole, to receive the nose of a pair of great bellows. The night 

 before they begin, charcoal is kindled in the furnace to anneal it: and when 

 hot, they throw 2 or 3 shovels of coal to one of the fore-mentioned stuff, and 

 so proceed during the whole work, which continues 3 days and nights without 

 intermission. After 8 or 10 hours the metal begins to run, and when the re- 

 ceiver below is pretty full, they lade it out with an iron ladle, and cast it into 

 sows in cavities or forms made with ashes. They frequently stop the passage- 

 hole with cinders to keep in the heat ; and when they think a quantity of metal 

 is melted, they unstop the hole to pass it off. If the matter be hard to flux, 

 they throw in some slag, which is the recrement of iron, to give it fusion. A 

 stinking blue smoke proceeds from the furnace, and all by-standers look like 

 dead men. To get the silver from these metals, they now use no other art than 

 that of the test; and the same to refine the copper from the litharge. 



The last way of separation is by quicksilver. And this is for filings of small 

 workers and goldsmiths, wherein gold and silver are mixed with dust, &c. This 

 dust is put into a hand-mill with quicksilver, and being continually turned upon 

 that and the metals, an amalgama is made of them ; then fair water poured in 

 carries off the dust, as it runs out again by a small quill. This amalgama is put 

 into an iron vessel with a bolt-head, set in the fire, having an iron-neck 3 feet 

 long, to which a receiver is fitted. The mercury distils off into the receiver, 

 and the gold and silver remain in the bolt-head. 



VOL. II. 3 N 



