258 Dr. Gorham’s analysis of sulphate of Barytes. 
Its fracture is laminated, and the lamina are frequently divided by 
thin layers of transparent amorphous quartz. When crystallized it is 
in the form, to use the language of Mr. Chilton, of “ rectangular bev- 
**elled tables, united into radial groups, which cross each other at 
‘‘ various angles of obliquity,” and about one sixteenth part of an 
inch in thickness. 
Before the blow-pipe it can hardly be fused without addition. In 
small fragments in decrepitates. 
Small portions of galena and sulphuret of copper are frequently dis- 
seminated through this substance. 
The specific gravity of this spar is 4°280, but it is difficult to ob- 
tain portions of any size unmixed with quartz, by which its relative 
weight is more or less influenced. 
~ 1, One hundred grains of this mineral exposed in a crucible of 
platina to a red heat for one hour lost 3 grains in weight. : 
2. One hundred grains reduced to an impalpable powder were 
mixed with 300 of sub-carbonate of potass and 1000 of water and boil- 
ed to dryness ina silver bason. Water was again added and the boil- 
ing to dryness repeated. Fluid was again poured into the vessel, and 
the whole thrown on a filter. The insoluble portion, when collected 
and dried, weighed 84 grains. 
3. On these 84 grains was poured muriatic acid, and when the ef 
fervescence had ceased the whole was passed through a filter, and the 
weight of the residue, perfectly dried, amounted to 34°2. 
4, These were mixed with 100 grains of carbonate of potass and 
a sufficient quantity of water and boiled to dryness, Water was again 
added, and the insoluble portion after filtration and érying weighed 
23°5 grains. 
5. These were treated as the above and 15 grains remained undis- 
solved. 
