172 Mr. H. L. Pattinson on the Smelting of Lead Ore, fyc. 



propelled forwards by the blast, and forced through the gateway, over 

 the breast of the test ; its place being supplied by a fresh quantity, so 

 as to keep up a continual stream. The Litharge concretes into lumps 

 as it falls, which are removed from time to time by the workmen in at- 

 tendance, who take care, by the addition of fresh quantities of Lead, 

 to keep its surface in the test always at the proper working level. In 

 this way the operation proceeds ; but as the hot Litharge gradually 

 wears down the gateway, so as to render the test incapable of holding 

 a sufficient quantity of Lead, it becomes necessary to make a fresh gate- 

 way, generally after two fodders of Lead have been refined. When this 

 is done, the blast is suspended, the old gateway is stopped up with a 

 paste of bone ashes, a fresh channel made on the other side of the 

 breast, and the test filled up with Lead to the proper level, as at first. 

 The process then proceeds again, until two fodders more of Lead have 

 been oxydized, when the second gateway being also worn down, until 

 the test does not contain more than one cwt. of Lead, the wedges sup- 

 porting it behind are slackened, and those in front taken away, and the 

 fluid Lead, called technically rich Lead, is poured into an iron pot 18 

 inches in diameter, running upon a carriage with four wheels. This 

 rich Lead, containing the Silver of four fodders of original Lead (usu- 

 ally from 30 to 40oz.) is cast into a pig and taken away, a fresh test is 

 applied to the furnace, and four fodders of lead worked in it, in the 

 manner described, until 50 or 60 pieces of inch lead are obtained. A 

 test is then made, the bottom of which is somewhat concave, instead 

 of being flat like those already mentioned, and in this the rich Lead is 

 carefully refined, yielding, at the end of the process, a cake of Silver 

 weighing from twelve hundred to eighteen hundred ounces. The 

 rich lead is treated in the same way as ordinary lead, except perhaps 

 more carefully, and after the last piece is introduced, the gateway is 

 made deeper with an iron tool, from time to time, as the surface of the 

 Lead subsides by its gradual conversion into Litharge ; and, from this 

 period until the cake of Silver is rendered pure, all the Litharge then 

 flowing is kept separate, as it is apt to carry along with it a portion of 

 Silver. The part received is called rich Litharge, and may contain 



