544 Intelligence and Miscellaneous Articles. 



conformable superposition of the micaceous schists or gneissose flag- 

 stones to the quartzite series, — the succession being visible at inter- 

 vals in all the intermediate country between Loch EriboU and Led- 

 more, and the passage upwards from the quartzites and their asso- 

 ciated limestones into the schists and micaceous Hags being both clear 

 and persistent, with some local interruptions only of igneous rocks, 



5. That the protrusion of porphyry, hypersthene, greenstone, &c. 

 is not peculiar to any one line, but occurs in the j^urple or Cam- 

 brian sandstone, in the overlying Silurian limestone of Durness, and 

 again in the still higher micaceous flagstones ; and that the latter, 

 when intruded upon by granite, much resemble the old gneiss. 



6. With regard to the Old Red Series of the east coast. Sir Ro- 

 derick pointed out the extension of the middle set of deposits, 

 namely the Caithness flags, — their great thickness in Caithness 

 compared with their development in the south, — and their range 

 over the Orkneys into the Shetlands, where they also thin out, put- 

 ting on a somewhat diff'erent lithological character, and where the 

 Old Red Series is chiefly represented by sandstones, the upper part 

 containing plants. He dwelt upon the great value of the Caithness 

 Flags as paving-stones, their extraordinary durability being due to 

 a certain admixture of lime and bitumen (the latter derived from 

 fossil fishes) with silica and alumina, whilst in some parts they 

 contain bitumen enough to render them of economic value. The 

 author next pointed out the passage of the Caithness flags upwards 

 into light-coloured sandstones, which eventually form the great 

 headlands of Dunnet and Hoy, where such overlying sandstones 

 cannot be of less thickness than 1200 to 1500 feet. 



With regard to the micaceous rocks of the North-east of Scotland 

 and the Shetland Isles, they are, according to the author, portions 

 of the series which is younger than the fossiliferous Lower Silu- 

 rian rocks of the west of Sutherland, — the so-called gneiss of the 

 Sutors of Cromarty belonging, in Sir Roderick's opinion, to the mica- 

 ceous-flag series of Eastern Ross-shire ; and the gneissic rock ex- 

 tending southwards to Flowerburn, Kinordy and Rosemarkie, near 

 Fortrose, is regarded by him as a member of that series, altered by 

 the intrusion of granitic and felspathic I'ocks. 



The paper was illustrated by a large series of rocks and fossils 

 poUected during the author's last tour, and by geological maps and 

 coloured views and sections. 



LXL Intelligence and Miscellaneous Articles. 



ON SOME PKOPERTIES OF ICE NEAR ITS MELTING-POINT. 

 BY PROFESSOR FORBES. 



DURING the last month of March, I made some experiments on 

 the properties of ice near its melting-point, with particular 

 reference to those of Mr. Faraday, published in the ' Athenrcum ' 

 and 'Literary Gazette' for June 1830, to which attention has been 

 jnore lately called by Dr. Tyndall and Mr. Huxley in relation to the 

 ph^enomena of glaciers. 



