72 Mr. Haidinger's Account of the Specific Gravity 



tion with the degrees of specific gravity. I have not, how- 

 ever, so far succeeded as to establish clearly the specific differ- 

 ence among these substances, which is indicated by several 

 of their properties. Mr. Mitscherlich is at present occupied 

 in ascertaining several of them ; and also in examining the 

 chemical composition of the substances themselves, in search 

 of the isomorphous bodies of sulphate of strontia and sul- 

 phate of lead. 



23. Di-prismatic Lead-baryte , (carbonate of lead,) columnar 

 compositions, perfectly white, almost opaque, from the Hartz, 6.339 



24. Di-prismatic Lead-baryte, similar composition, but of a 

 yellowish colour, superficially almost brown, from the Hartz, 6.417 



25. Di-prismatic Lead-baryte, greyish-white, easily cleavable 

 crystals, from Bleiberg, Carinthia, 6.461 



26. Di-prismatic Lead-baryte, fragment of a white strongly 

 translucent crystal, from Leadhills, 6.465 



27. Rhombohedral Lead-baryte, (phosphate of lead) a single 

 green crystal, from Zschopau, Saxony, 7.098 



28. Arseniate of lead, bright yellow crystals, from Johanngeorg- 

 enstadt, Saxony, 7.212 



There is a considerable difference between this and the 

 preceding variety in regard to specific gravity, but there is 

 likewise a difference in the form. I found the inclination of 

 the faces of the pyramid at the base = 80° 45' in a green va- 

 riety of phosphate from Freiburg, = 80° 44', in a green va- 

 riety of the same from Cornwall, = 79° 40', in the yellow ar- 

 seniate from Johanngeorgenstadt ; the correspondent angle in 

 phosphate of lime is = 80° 25'. 



29. Hemi-prismatic Lead-baryte, (chromate of lead) several 

 isolated crystals from Siberia, 6.004 



30. Pyramidal Lead-baryte, (molybdate of lead) longish deep 

 wax-yellow crystals, from Bleiberg, Carinthia, 6.698 



31. Pyramidal Lead-baryte, fragments of an orange-yellow, 

 perfect crystal, from Annaberg, Austria, 6.760 



32. Prismatic Lead-baryte, (sulphate of lead) broad deeply 

 striated crystals, of a white colour, and faint translucency, from 

 Leadhills, 6.228 



33. Prismatic Ijead-baryte, crystals similar to the preceding, 

 but of a brownish colour, from Leadhills, 6.255 



34. Prismatic Lead-baryte, a white translucent tabular crystal, 



from Leadhills, 6.298 



35. Prismatic Lead-baryte, fragments of a large semitranspa- 



rent crystal, from Leadhills, 6.309 



2 



