184 
Lead. 
ash, and kept for some time in a red heat in a piatina cru- 
cible, which gave a reddish-yellow hardened mass. This, 
digested with water, was all dissolved except the oxyd of 
lead separated in the previous process, amounting to 72 
grains, after strong drying. This oxyd was redissolved 
in nitric acid, and deposited thereby one grain of oxyd of 
iron. The solution was then decomposed by zinc, and 
yielded 66.5 grains of metallic lead. The alkaline fluid 
formed by the washing of the contents of the crucible, af 
ter ignition, was then saturated with nitric acid and acetate 
of barytes added as long as any sulphat of barytes was 
precipitated. This amounted to 73 grains, equal to 24.8 
of concrete sulphuric acid on the estimation that 100 parts 
(after ignition) contain 34 of acid. The iron in this ore 
appears merely casual. 
The phosphated lead ores have been also examined by 
the same eminent Chemist with much attention. The 
composition of all the varieties is very uniform, all con- 
sisting of phosphoric acid and oxyd of lead, together with 
muriatic acid, the quantity of which varies very little. It 
is a distinguishing and singular property of the phosphat 
of lead, that when melted into a round bubble under the 
blow-pipe it assumes a regular polygonal garnet-shaped 
form on the moment of solidifying by cooling. 
The green phosphat was thus analyzed : after some 
imperfect attempts at reduction in the dry way, 100 grains 
of the ore were dissolved in hot nitric acid leaving no re- 
sidue. Nitrat of silver then gave a precipitate of 11 
grains of luna cornea, the muriatic acid of which amount- 
ed to 1.7 grains. Sulphuric acid was then added to the 
warmed solution, by which sulphat of lead was precipitat- 
ed, weighing after ignition 106 grains, equal to 73.61 of 
metallic lead or 78.4 of the oxyd. The liquor was then 
freed from the excess of sulphuric acid by nitrat of bary» 
tes, it was then nearly saturated with ammonia* and ace* 
