182 
Lead, 
washing with water, some black oxyd of copper was left 
weighing 32 grains after thorough drying. 
In the above analysis the metals are estimated as in 
their metallic state, this being the state in which they exist 
in the sulphurets, and hence, for the 63 grains of oxyd of 
antimony, 48.45 of the regulus are to be put down, and 
for the 120.2 of sulphat of lead, the author estimates 85.24 
of metallic lead, which is in the proportion of 70.9 in 100. 
The carbonat of lead was analyzed by Klaproth in the 
following way : 100 grains were dissolved in a mixture 
of 200 grains of nitric acid with 300 of water, and the 
loss of weight by the effervescence noted, which amount- 
ed to 16 grains, and was carbonic acid. The nitric so- 
lution was then diluted, and a cylinder of zinc immersed, 
which precipitated the lead in the metallic state in beauti- 
ful vegetations. This washed and dried, weighed 77 
grains, equivalent to 82 of oxyd, as it is in this state that 
the lead exists in the ore. This proportion however, would 
give an increase of only 6.5 of oxygen upon 100 of lead. 
That rare variety of lead ore, the compound carbonat 
and muriat of lead, has been analyzed both by Klaproth 
and Chenevix. By Klaproth, the following method was 
pursued : fifty grains of the ore were rubbed with 15Q 
of very pure carbonat of potash, (previously freed from 
every muriat) and heated in a platina crucible to a mode- 
rate redness, then lixiviated and filtered. An oxyd of 
lead was left behind. The solution was slightly super- 
saturated with nitric acid and precipitated with nitrat of 
silver. The muriat of silver thus obtained weighed 2 7 
grains, equal to more than 4 of concrete muriatic acid. 
Another quantity of the ore of 100 grains was then pow- 
dered and nitric acid affused, which produced an efferve- 
scence of carbonic acid. This solution gave with nitrated 
silver^ 5 grains of luna cornea, corresponding very close- 
ly in proportion with the former experiment, the acid of 
