in Glen Farirr, in Inverncas-sMre. 269 



ready mentioned ; but its working will, as is the case with all 

 minerals occurring in imbedded masses, be less certain than 

 when it occurs in regular beds or veins. 



The occurrence of graphite in gneiss has been observed in 

 other countries, as in Spain, where its mode of distribution is the 

 same as in this glen. It is also one of the minerals mentioned 

 in my Account of the Rocks of the Arctic Regions, published 

 with the Voyages of Captain Parry, as having been met with in 

 the arctic regions of America. In Scotland it is not confined to 

 Glen Farrer, as there are two localities of it in the county of 

 Ayr, where it is associated with rocks of the coal formation, 

 viz. near New Cumnock, and at Stair, on the water of Ayr. 



This interesting mineral is generally considered as a chemical 

 compound of carbon and iron, and as such it figures in chemical 

 works under the name of native carburet of iron. The experi- 

 ments of Karsten, however, shew, that the pure varieties of gra- 

 phite contain not an atom of iron, and that it is only the impure 

 kinds that contain oxide of iron, and occasionally also oxide of 

 titanium, silica, and alumina. Grapliite, therefore, is a pure 

 carbon. 



Having finished our rapid glance of this interesting spot, we 

 returned in the evening to Beauly. In our walk down the glen 

 we noticed more particularly the narrowings and widenings that 

 occur in its course to the Falls of Kilmorack. Of these we 

 reckoned five. These alternate widenings and narrowings of the 

 valley, the richness of its wooded banks and mountains, and the 

 tumult and noise of the river, as it forced its way through the 

 narrow rugged rocky passes, contrasted with its quiet and almost 

 still course through the wider parts of the valley, formed alto- 

 gether a scene not exceeded in natural beauty or geological in- 

 terest by any other glen in Scotland. 



2. Walk from Aberdeen to the Castleton of Braemar — 

 country around Castleton— ^rom Castleton to the Sptttal of 

 Glen Shee and Blair-Gowrie. — The country around Aberdeen 

 is almost entirely composed of primitive rocks. Of these there 

 are two .sets, the Neptunian and Plutonian. The Neptunian are 

 certain varieties of granite subordinate to gneiss, gneiss, mica- 

 slate, hornblende-rock, hornblende-slate, hornblendic gneiss, &c.; 



