On Cupellation with the Blowpipe. 411 
lead entirely free from silver. The German granulated lead pre- 
pared. expressly for this purpose, contains a notable quantity of 
silver. Nitrate of lead and acetate of lead when reduced and cu- 
pelled yield silver; and I have precipitated lead with zine, reject- 
ing the half of the lead first precipitated, as being that likely to 
contain all the silver, and saving only that part precipitated last, 
and still found it to contain silver. As lead absolutely pure seems 
to be unattainable, I estimate the difference between the weights 
of peraninsion glo obules , obtained from the metal or ore, and from 
'* These weights are easily made by a little skill in manipulation. To make 
moderately smail weights I have used silver lace, which when yaa" pled is a 
1s gees with flattened wire of silver of ep tenuity. I how 
many inches of this gave 1 grain of silver, and t y means of dividers anda 
sector Seale, cut off such lengths as would make met Tr 
With the sector scale, +45 and even zdy of an inch can be measured 
red and twenty inches in 9 th oft the lace, pate 2:2 grains bsileer: Twelve 
Inches = -22 ron, 1-2 in. = 0-022 grain, 0-12 in. = 0-0022 grain, &c., and 
generally, 120 in: 2 2-2sgrs. 3: 2 length required : y the weight required. If y 
= oho grain, ‘iin 120 in. : 22: ‘rove . © = gl¥y inch, which is vautiy 
off on the oa aig scale. Having ie length cut off, moisten it with borax wa- 
terand melt o he borax water enables the silver to coalesce without 
rating Fite? aah globules, as it Id do, i w fe) moistened and 
rolled up into a little pellet. T is so small in quantity, where the 
is moistened with borax water, that it does not dissolve any sensible quantity of 
silver. By rolling the moistened thread into a little pellet, I can easily make all 
hp water coalesce into a single globule when the thread is ten to twenty i 
th. 
nt still smaller weights I use fine plated copper wire, and cu That ased 
is from an epau pit of ue ch by ne analysis, I found 1800 ee #8 length gave 
16 grains of silve er, inches in length for 1 grain of silver. 135 hes then 
Would give a ae sei » 1:35 inches = rou grain eins, eres 0-135 
aherg of si This is no mapa PR accurate, as little of os oe 
. se. 
d A ay tesa method; enclosing a 
wire, with a hole drilled to let 
