8<5 Extract from tke third Vblwneqf 



striated. When the charcoal inflames at the place u-here the 

 globule adheres to it, the latter breaks in pieces, the mu- 

 riatic acid escapes in white vapours, and the charcoal is 

 covered with grains ot" nictallic lead. 



M. Klaproth has found in t4ie crystals of muriate of lead 

 treated by potash in a platine crucible, and by nitric acid. 

 Oxide of lead - - - Sj-50 



Muriatic acid - - - S*50 



Carbonic acid, with a little water 6 



100 



Artificial muriate of lead contains 13 or 14 per cent, of 

 concrete muriatic acid, while natural muriate of lead is not 

 completelv saturated ; which explains why the carbonic acid 

 may be found there at the same time as muriatic acid. 



Analyses of the Green Phosphate of Leadof Zschopan. 



This ore is composed of hexaiidral prismatic crystals, ter- 

 minated by planes perpendicular to the axis. They are 

 sometimes single, and sometimes formed intogroupes; some 

 of them are two inches in length. They are of an olive or 

 green, sometimes inclining to meadow-green, and often 

 to pale yellow ; when pounded, they give a straw-coloured 

 powder. The crystals, when very pure, have a smooth 

 surface and a greasy polish ; they are generally covered with 

 a stratum of ochre which renders them rugged. The matrix 

 from which they are extracted is white sulphate of barytes. 

 The specific gravity of this substance is 6'270. 



This phosphate of lead, when exposed on charcoal to the 

 flame of the blow-pipe, fwes into an almost transparent 

 globule ; but it becomes opake by cooling, and soon cry- 

 stallizes under the form of a polygonal garnet, with brilliant 

 facets on the side which touches the charcoal. There are 

 generally found small grains of lead reduced to the metallic 

 state, but it is never entirely reduced without a flux. It 

 participates in this property of crystallizing, by cooling, with 

 all the ores of phosphate of lead hitherto known, as well 

 as with artificial phosphate of lead. This observation had 

 before been made by Cronstedt. 



To fuse this ore a very strong heat is required; for M. 

 Klaproth extracted it without its having experienced any al- 

 teration except at its edges, which were a little blunted by 

 the muflle of a cupelling furnace, in which he had effected 

 exceedingly well the separation of gold ; but it fused 

 completely in a blast-furnace, and crystallized in radii by 



cooling. 



