16 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
On 1° 2 grammes— 
Silica, : : ; *458 
From Alumina, . : *016 
‘Aya == B0R 
Alumina, . : 2 . 15-036 
Ferric Oxide, . : ; "244 
Ferrous Oxide, . : . 1L0°229 
Manganous Oxide, . ‘ 75 
Lime, : ; : a eles: 
Magnesia, . : . 18°461 
Pasty ci Moe aflame nabs 
Soda, ‘ ; 3 : *618 
Fluorine, . ' : a 2) 
Water, ; ; . 3§°214 
99° 558 
Insoluble silica, 2°531 per cent. Possible impurity, chlorite. 
3. From the limestone at Shinness, Sutherland. Biotite, similar in appearance 
to the last, is to be seen rarely at this locality. More frequently it occurs 
in dark-brown almost black plates which sheathe sahlite, and still more fre- 
quently in the form which was chosen for the analysis,—namely, in small 
crystals superimposed on one another, so as to present a foliaceous structure. 
It was in immediate association with sahlite and brown sphene. 
The crystals were of a light greyish-brown colour, and a greasy lustre ; they 
were suspected to be phlogopite. 
1°3 grammes yielded— 
Silica, ‘ : ’ Jaye) 
From Alumina, . : -004 
Dilly, ==  aoeno9 
Alumina, . ; : > 26" G76 
Ferric Oxide, . : 2 *653 
Ferrous Oxide, . : epee 
Manganous Oxide, . ; 615 
Lime, ; ‘ . 5 PG 
Magnesia, . ; . 5 620923 
Potash;  . : d » WENO 
Soda, : : : : “476 
Water, . ; Re suai re) 
99 + 936 
Insoluble silica, 1°74 per cent. Possible impurity, sahlite or sphene. 
