Chemical Composition of the Brown Lead Ore. 319 
One hundred parts of this mineral consist of: 
Oxide of lead, - - 82.290 
Muriatic acid, - 1.989 
Phosphoric acid with a trace of sae of ir iron and loss, 15.724 
or 100.000 
1 atom chloride of lead = - - - 10.069 
33 atoms phosphate of lead = é - 89.931 
100.000 
The following table is arranged to facilitate a review of the re- 
sults concerning the chemical composes of the varieties of Brown 
Lead Ore herein examined. 
Pies z es = £ pa 
4 8 £0 ie i 
Bee jee | 28 | eel oe = 
Brown lead oreof| — | 23 | E5| 82 | $2 |38 3 
z = 
ee es BS Lees ee oa 
D oO i= oh ou 
Sonnenwirbel oe 
mine. ease & 6.092)}10.838)1.094/11.053/77.015) — |100.000 
Mies. (am mor ph. )] 16.444'10.642'0.248| 7.457/81.65litrace| 99.998 
Mies. teen. ) 5.983) 9.664/0.219| 0.848|89.268 — | 99.999 
Bleistadt: do. /7.009) 9.918/0.137| 0.771/89.174| — |100.000 
England. do. | — /|10.07 0.130, 0.662/89.110) — 99.996 
Poullaouen. do. |7.048/10.0 — /|89.910tra if 
(do. amorph.) |7.050110.069| — | — /89.931/trace|100.000} 
From the researches of Mr. Woéhler relating to four Phosphates 
and Arseniates of Lead it follows, as I have before remarked, that in 
the mineral Phosphates and Arseniates, a mixture in indefinite propor- 
tions, or a complete replacement of principles may happen, without 
giving rise to any variation in the crystalline form, or to the relative 
proportion of the lead in the basic salt, or to that in the chloride of 
lead. From the results of the analyses of the seven varieties of 
Te Lead Ore, I think we can deduce the following conclusions. 
1. The Brown Lead Ores are partly combinations of one atom chlo- 
ride of lead and fluoride of calcium with three atoms and two thirds 
of phosphate of lead, and ‘two thirds of phosphate of lime,—partly of 
one atom chloride of lead with three atoms and two thirds phosphate 
of lead, and correspond in the first case, to the formula, 
Pb€! Pb? =e: 
43. $ 
CaF Ca* : 
in the second, to, fee 
Pbel+3Pb°B 
* 
