174 Mr. H. L. Pattinson on the Smelling of Lead Ore, 8$c. 



The deposit called refiner's fume, is removed from the horizontal 

 fines from time to time, and is frequently ground up with oil, forming 

 a very cheap and durable paint ; but the quantity produced is generally 

 too considerable to admit of the whole being disposed of in this way, 

 and the surplus is reduced by being roasted almost to fusion, and then 

 worked in the slag hearth, in the same manner as grey slags. As might 

 be expected, the Lead obtained from the test bottoms and refiner's fume, 

 contains but a very small portion of Silver. 



Instead of converting into Litharge but four fodders of Lead in each 

 test, as already mentioned, some refiners are in the habit of working 

 twelve or thirteen ; but, in this case, the tests are constructed with 

 peculiar care, and the bottom, sides, and breast are made thicker than 

 usual. The Litharge from four fodders of Lead, flows through the first 

 gateway made on one side of the breast, and when the quantity of Lead 

 in the test is reduced to about a cwt., it is cast into a rich pig : four 

 fodders of Lead are then worked through another gateway, on the op- 

 posite side of the breast, yielding a pig of rich Lead in the same man- 

 ner ; and, for the remaining four fodders, a gateway is made across the 

 middle of the breast. By adopting this method of working, the loss 

 from the Lead absorbed by the test bottoms is considerably lessened, 

 and a great saving is made in the expense of tests ; but the process is 

 rendered slower, as it is necessary to work at a low degree of heat. 

 The saving in tests is not what it appears to be at first sight ; for those 

 made to refine the larger quantity of Lead, being thicker and stronger 

 than the others, require a larger quantity of bone ashes. 



The rate of refining varies a little, from the cause just stated. When 

 four fodders of Lead are oxydized in a test, it is usual to accomplish 

 this in from 16 to 18 hours ; and six tests, or 24 fodders of Lead, can 

 be very easily converted into Litharge, in one furnace, by three men in 

 a week. The quantity of Coal consumed is about four Winchester 

 bushels, or three cwt. avordupois, per fodder of Lead. In cases where 

 12 or 13 fodders of Lead are refined in a test, it is customary to work 

 but one test in a week, in one furnace, which is only half the quantity 

 stated above ; but here also, three men by managing two furnaces re- 

 fine 24 to 26 fodders of Lead per week. 



