PROCESS FOR REFINING LE^D. g 



which contains the lead to be refined, n breast of the test, 

 o o small gutters or channels through which the litharge 

 flows, jj a semi-eliptical hole for the litharge, to fall 

 through from the gutters upon the area of the refinery. 



These drawings and references will be sufficient to 

 make the description of the furnace, &c. clearly under- 

 stood. 



Of the lest or Cupel. 



A good testis of the first importance in refining ; the made of'eDart* 

 method of constructing one I shall endeavour to point out. bone and i fern 

 Six parts of well burnt bone ashes and 1 part, of gOod ashes. 

 fern ashes are to be well mixed, sifted through a sieve (the 

 spaces in which are about ^ of an inch square), and 

 moistened to about the same degree the founders use their 

 satid. The iron frame is to be laid on the floor and made 

 steady, with wedges under its rim ; about two inches in 

 thickness of the ashes are to be equally spread over the 

 bottom, and with an iron beater, such as used by the 

 ' founders, equally rammed between the cross bars ; the 

 frame is to be again filled and rammed all over, beginning 

 at the circumference and working spiral ways until 

 finished in the centre, the filling and ramming to be re- 

 peated until the frame is completely full ; an excavation 

 to contain the lead is made as expressed in the plan, with 

 a sharp spade about 5 inches square, the edges dressed 

 with a long-bladed knife; a semi-eliptical hole, as atj^;, is 

 to be cut through the breast. Having proceeded so far, 

 the test is to be turned on its side and dressed from all 

 superfluous ashes adhering to the bottom, taking care that 

 none shall be left flush with the bottom of the frame or 

 cross bars, otherwise in fixing the test to its situation at 

 the bottom of the furnace it would be liable to be bulged. 

 Fixing the Test in its situation. 



The rim of the test is now to be plastered with clay or Manner of fix- 

 moistened ashes, placed upon the supporting cross bars, *"S ^^ '"'* 

 and fixed with wedges firmly against the bottom of the 

 furnace, the breast next to the feeding hole. 



A gentle fire may now be lighted, and gradually in- 

 creased until the test bo red hot. When it ceases to emit 

 5team from the under side it is sufllciently dry. 



Lead previously melted in the. iron pot /is ladled into Manipulation 

 B2 the^y ^^'"^ '^^"^ 



