516 Chemical Composition of the Brown Lead Ore. 
Oxide of lead, - - - - - 81.460 
Muriatic acid, - - - - 1.956 
Lime, - - - - - 0.320 
Phosphoric and fluoric acids, and loss, - 16.264 
100.000 
The constitution of this Brown Lead Ore, estimated by the prece- 
ding formula, and based upon the ascertained proportions of chlorine 
and oxide of lead, is as follows: 
Chloride of lead, - - = - 9.918 
Fluoride of calcium, - - - 0.137 
Hesic Phosphate of lead, - - -* 89.174 
lime, - - - 0.771 
: 0.000 
5. Crystallized Pinon sane Ore from England. Thi Brown 
Lead Ore forms up shaped crystals of a liver- 
brown color, which are perfectly transparent, and of an adamantine 
luster. I am-not exactly informed of the precise locality of this va- 
riety: I purchased my specimens, furnished with the above ticket in 
German, last year at Lyons of a mineral-dealer, named Lafont. Be- 
fore the blowpipe, it exhibits the same reactions as the varieties be- 
fore enumerated. When treated with soda, no smell of arsenic was 
afforded ; neither did its solution tested in several ways afford any © 
signs of the presence of this metal. Examined with sulphuric acid, 
I easily obtained though only in a feeble manner, signs of the pres- 
ence of fluoric acid: in like manner also a very small proportion of 
lime was rendered obvious, by adding, after the separation of the 
lead, to the concentrated solution, sulphuric acid mingled with alco- 
hol. The analysis of this ore could only be performed upon 0.9 
grammes, which gave for the one hundred — 
Oxide of lead, - - 82.083 
Muriatic acid, - - - - 1.990 
Lime, Aes Hotes i84 - 0.320 
Phosphoric and fluoric _— with loss, 15.607 
100.000 
These results, estimated ES to the formula adopted above, 
and calculated upon the basis of the quantities of oxide of lead and 
muriatic acid ascertained in the analysis, give, 
