322 Magnesian Limestone . 
chromat of iron. I tried the specific gravity of three of them, which 
varied from 2,65 to 2,72 the visual range of common limestones. 
No. 1. Holstein : Colour, greyish white : Fracture, uneven : Sur- 
face, common splintery : the stone seems to consist of minute lus- 
trous chrystals: slightly fetid on being pounded. I obtained 
in 100 parts, silex 3, alumina 2, carbonat of magnesia 12. The 
rest was carbonat of lime or pure limestone. The traces of 
iron were evident with tincture of galls and prussiat of potash, but in 
no greater degree than might be attributed to the usual impurity 
of the acids of commerce. My muriatic acid was freed from the 
sulphuric, by muriat of Baryt. 
No. 2. Coates's. Colour, greyish white: Fracture, uneven: 
Surface, fine splintery, consisting of minute sparkling chrystals, 
I obtained in 100 parts, of silex 3, alumina 2, carbonat of magnesia 
14. The rest was pure limestone. 
No. 3. Yocum's. Colour, greyish white streaked with blueish grey, 
being coloured with hornblende (amphibole.) Fracture uneven s 
Surface, splintery, small sparkling chrystals. I obtained in 100 
parts, silex 4, alumina 2, carbonat of magnesia 14. The rest was 
pure limestone. 
No. 4. Cleaver's. Colour, blueish grey : Fracture uneven in one 
direction, but splitting into laminae of about \ an inch thick in the 
other ; there was a very thin clay coloured sediment between the 
luminae : Surface, opake, without lustre. I obtained from 100 
parts, silex 4, alumina 6, carbonat of magnesia 14. The rest was 
pure limestone. 
No. 5. Hughes's. Colour, white inclining to grey : Fracture un- 
even : Surface splintery, opake, void of lustre. I obtained from 
100 parts, silex 5, alumina 2, carbonat of magnesia 12. The rest* 
pure limestone. 
No. 6. Dr. Gardener's. Colour greyish, inclining to blueish 
White. Fracture uneven: Texture, a very fine, easily-pounded, 
sandy grit, consisting of minute lustry chrystals. I obtained from 
100 parts, silex 2, alumina 0, carbonat of magnesia 16. The rest* 
pure limestone. 
No. 7. Barnet's. Colour, white with a very slight clay coloured 
tinge: Fracture uneven: Surface, chrystailized lustry facets: 
Texture, saccharoid, the same as the saccharoid limestone on the 
York turnpike road about 10 miles from Baltimore. I obtained, 
silex 1 , alumina 0, carbonat of magnesia 14. The rest, pure lime- 
stone. 
