TRANSACTIONS OF THE SECTIONS. 53 



most desirous of finding a mode by wliicli the object could be accom- 

 plished at once. Conceiving tliat tlie crystals would be rendered poorer 

 if more thoroughly drained from the liquid lead, he adopted the plan of 

 exposing them, after removal from tlie pot to a cautiously regulated 

 heat in the chamber of a reverberatory furnace, so as to melt out from 

 among them a further portion of liquid lead ; and in this way he suc- 

 ceeded in obtaining at one operation from original lead holding 12 

 ounces of silver per ton, four parts of poor lead containing not more than 

 ^ of an ounce per ton, and one part of rich lead containing 50 ounces 

 per ton, or thereabouts. This was effected at a moderate expense, and 

 with a very inconsiderable loss of lead ; and the new process thus ar- 

 rived at, which he called the process of separation, was immediately 

 adopted and carried on in this way for some time at different lead- works 

 in the kingdom. 



The exposure of the crystals a second time to heat, required, how- 

 ever, a peculiar and rather expensive apparatus, and Avas found somewhat 

 difficult to get managed properly, for the workmen could not always keep 

 the furnace in which it was performed at the exact temperature neces- 

 sary for the operation ; and it often happened that, by the application 

 of too much heat, the crystals were melted entirely without being drained 

 of their richer lead ; besides, the lead exposed to heat in its crystallized 

 state was oxidized rapidly, and the subsequent reduction of the oxide 

 occasioned some loss of metal. These objections to the draining pro- 

 cess induced the author to recommend in preference the simple plan of 

 repeated crystallization, which has been everywhere adopted, and now 

 constitutes the process of separation ; experience and practice have gra- 

 dually rendered it easy and perfect, and it has become an established 

 operation among the arts of this country. 



The apparatus required for the separating process is exceedingly sim- 

 ple, and consists merely of a number of nearly hemispherical iron pots, 

 each capable of holding about five tons of lead, the size for which is about 

 4" ft. diameter and 2 ft. 3 in. deep ; one or two smaller pots, 18 in. diameter 

 by 2 ft. deep, are required for the purpose of holding melted lead, in 

 which the perforated iron ladles ai'e to be occasionally dipped to keep 

 them hot; and another pot, about 2 ft. 10 in. diameter by 1 ft. 10 in. 

 deep, for melting the ultimate poor lead to be cast into pieces. These, 

 with a few perforated iron ladles 15 in. diameter, and 5 in. deep, and 

 one or two whole ladles of lesser size for casting the melted lead 

 into pigs, are the principal articles required. The large pots are to be 

 placed side by side in a line, each with a separate fire-place, (upon 

 which there must be an ash-pit door as well as a fire door,) and also with 

 a separate flue and damper, so that the draught imder each pot can be 

 entirely stopped by closing the flue with its damper, and the heat of the 

 fire-place in some measure retained by shutting the ash-pit door. Above 

 the centre of this line of pots, at the height of six or eight feet, it is con- 

 venient to have a small iron railway, with a frame or carriage on four 

 wheels to move backwards and forwards the whole length of the range 

 of pots, from which is to depend a chain, terminated by a hook at the 

 bottom, and reaching to nearly the top of the pots. This is for the 



