PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 73 
On 1° 519 grammes— 
Silica, : : “360 
From Alumina, . * 006 
‘369 = 24° 292 
Alumina, ; : : Pol 9 
Ferric Oxide, 3 : “201 
Ferrous Oxide, . : 18-739 
Manganous Oxide, : °8 
Lime, . H 2 : 1:°659 
Magnesia, . ; : 21.* 033 
Potash, . ‘ ; é 1° 286 
pods, +". ; t 564 
Water, . 5 ? f 10° 083 
8-13 per cent. of the silica insoluble. 
From Granular Limestone in Mica Slate. 
4. The bed of limestone which appears near the house of Lude, running 
parallel to that of Glen Tilt, contains small imbedded masses of a pale olive- 
green colour, sometimes slightly browned. The structure is minute scaly, and 
the scales are so soft that the mineral has been thought to be “ potstone.” 
Specific gravity 2 : 852. 
1° 4635 grammes yielded— 
Silica, F 2 Boag 
From Alumina, . °019 
Oo = 23 * 922 
Alumina, j : ; 22-976 
Ferric Oxide, . : : 1:106 
Ferrous Oxide, : F 19°54 
Manganous Oxide, . ; "28 
Lime, . : : , 2° 453 
Magnesia, . ; 17° 259 
Water, . , p , 11: 784 
99-39 
5°67 per cent. of the silica was insoluble: possible impurity, lime. 
5. In the same quarry, translucent quartz in layers rarely cuts the lime; and 
this quartz contains chlorite, which differs from the above only in being of a 
