226 
Lead . 
vessel, in a groove, so as to be taken out occasionally ; 
these boards are bored, with a centre-bit, as full of holes 
as may be, without danger of breaking into each other ; 
the size of these holes is, in the machine at large, about 
five- eighths of an inch in diameter. This being done, 
the vessel is filled with water, about three inches above 
the oak boards or riddles ; the lower brass roller is riow 
under water, and about half of the upper roller is under 
water also. Thus the lead coming from the stacks, is 
put through die brass rollers in water, and, by raking the 
lead with a copper rake, over the oak boards or riddles, 
the white lead passes through the riddles, and the blue 
lead remains above ; which, being taken out, is thrown 
upon an inclined plane of strong laths to drain, where it 
remains about 12 hours, when the blue lead is ready for 
the furnace to be re-melted ; by this means no dusty white 
lead can rise in any part to the work-people. No such 
plan as this (though long desired) has, to my knowledge, 
been put in execution, so as to answer all the purposes 
above stated. It may be asked, why the lead in the com- 
mon mode, is not made wet before it is passed through 
the rollers and screen. Should this be done, the lead 
Would be a paste on the rollers and screen, and the white 
lead prevented separating from the blue lead, which is ab- 
/ solutely necessary in the preparation of white lead. 
Reference to the Figure. 
Fig. 1, A, an inclined plane of wood, on which the 
white and blue lead is placed immediately from the stacks, 
and thus introduced between the brass rollers BB. 
CC, the vessel containing water. 
DDD, the pierced oak boards or riddles, which, by be- 
ing made to slide in grooves in the sides of the vessel CC, 
may occasionally be taken out by removing the wooden 
bar ee. 
