ANALYSIS OF A NEW SPECIES OF LEAD-ORE. 253 



appearance of steel-grained galena, only the colour 

 is darker, and it shews the granular concretions 

 which distinguish that variety of sulphuret of lead. 

 But, in a few days, this fracture tarnishes, loses its 

 metallic lustre, and speedily becomes similar to the 

 external surface of the specimen. 



The fracture is small-grained uneven. The ex- 

 ternal lustre glimmering, and semi-metallic. The 

 internal lustre splendent and metallic. Soft, easily 

 scratched by a knife. Streak, lead- blue. Rather 

 sectile. Specific gravity, 6.590. But Dr Heyne 

 informed me, that he had found pieces as light 

 as 4 9^ 



Strong nitric acid acts upon this ore, when re« 

 duced to powder, with great violence ; but when 

 the acid is diluted with water, the action is scarce- 

 ly perceptible. 



A hundred grains of the ore in the state of pow- 

 der, were treated with an ounce measure of strong 

 nitric acid. The action was so violent, that I was 

 obliged to moderate it by the addition of water. 

 When this portion of acid ceased to act, it was de- 

 canted olF, and an additional portion substituted in 

 its place. After two days, all action was at an end. 

 Part of the ore was dissolved, and part was in the 

 state of a white powder. This white powder be- 

 ing separated by the filter, washed and dried in the 

 open air, weighed 58,5 grains. When exposed to 

 the heat of a lamp on a watch-glass, it gave out 

 fumes of sulphur, and the weight was reduced to 



