214 
Lead, 
Figs* 2 and 3, plan and section of the test ; m the part 
which contains the lead to be refined, n breast of the 
test, 00 small gutters or channels through which the 
litharge Hows, p a semi-elliptical hole for the litharge 
t6 fall through from the gutters, upon the area of the re- 
finery* 
These drawings and references will be sufficient to 
make the description of the furnace, See* clearly under- 
- stood. 
Of the Test or CupeL 
A good test is of the first importance in refining ; the 
method of constructing one I shall endeavour to point out* 
Six parts of well burnt bone ashes and one part of good 
fern ashes are to be well mixed, sifted through a sieve,, 
(the spaces in which are about one-eighth of an inch 
square,) and moistened to about the same degree the 
founders use their sand. 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 equal- 
ly 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 repeated until the frame is completely full ; an ex- 
cavation to contain the lead is made as expressed in the 
plan, with a sharpe spade about five inches square, the 
edges dressed with a long bladed knife ; a semi- elliptical 
hole, as at />, is to be cut through the breast. Having pro- 
ceeded so far, the test is to be turned on its side and dres- 
sed 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. 
