306 
THE GEOLOGIST. 
2. "On an Experiment in melting and cooling some of the Rowley Rag." Ry 
W. llawkes, Esq. C'omnninieateil by the President. 
About 31 cvvt. of basalt was melted in a large double reverberatory furnace, anil 
after a slow cooling during 13 days, it presented un ujiper stratum of stony 
vesicular matter, about 1 inch thick, next a layer of black glass, from 2 to 8 inches 
deep on that side of the mass which was exposed to the air from the door of the 
furnace (elsewhere, immediately under the vesicular layer was solid stone, inter- 
spersed here and there with air-bubbles). Mr. Hawkes added some observations 
relating to the results of exi)eriments which he had made to ascertain the tempera- 
ture of melted cast iron, and of melted basalt. 
3. "On the Iron ores of Exmore." By Warington Smyth, Esq., M.A., Sec. Geol. 
Soc. 
The author described the occurrence of ores of iron within a district of 
about thirty miles in length, between Ilfracombe and the Bridgewater Flats, in 
slaty rocks belonging to the " greywacke " of De la Beche's " Report on Cornwall," 
or to the " Plymouth Group " of the Devonian System, as described by Sedgwick 
and Murchison. They are situated partly to the north, but chietly to the south, 
of the irregular bands of limestone which pass from Combe Martin eastward by 
Simonsbath to Cutcombe and Treborough: The really stratified deposits of iron- 
ore are bands of argillaceous nodules, alternating with shales, similarly to those of 
the coal-measures ; and these have been found in abundance on the flank of 
Ilangivian Hill near Comb Martin, and in the north forest of Exmoor ; but in 
general, their angle of inclination is too great to allow of their being worked in 
competition with the analogous ores of the coal-fields. 
The lodes containing iron-ore, extensively worked some centuries ago, and which 
have recently been explored in the Brendon Hills, and tested on the property of 
T". W. Knight, Esq., M.P., are so nearly conformable to the beds of slate, striking 
about E. 10 degs. S., with a dip of from 45 degs. to 65 degs. southward, that they 
might be easily taken for stratified dc])osits. 
In several places, as at Cornham Ford, the Roman lode, and the little Woolcombe 
lode, haematite has been found at or near the surface, containing OS' l per cent, of 
peroxide of iron, in masses which present the structure of sjiarry iron or carbonate. 
Most of the lodes, however, especially those of the Deer park on Exmoor, and 
Raleigh's Cross, consist of brown or hydrous peroxide, generally occurring in large 
cavernous masses, with the interior of the cells often lined with brilliant but 
minute crystals of Goethite (pure hydrous peroxide), yet exhibiting the rhombo- 
hedral structure of sparry ore. Analysis shows this ore, especially from certain of 
the Exmoor veins, to contain 71'3 per cent, of peroxide of iron, together with a 
considerable per-centage of oxide of manganese. 
Lastly, several of the veins prove in depth to consist of sparry ore (siderite or 
carbonate of iron), containing a notable per-centage of carbonate of manganese. 
'J'his has especially been shown at Goosemoor, Huel Eliza, Hangley Cleave, and on 
Kentisbury Down. The width of these veins varies from a few inches to above 20 
feet, and at the greatest depth hitherto reached, 110 feet, there is no deteriora- 
tion in size. Quartz-veinstone and fragments of slate occasionally fill part of the 
lodes, and this fact, coupled with the interruptions of "slides "and "heaves," has 
led to some misplaced disappointment on the i)art of those who made their 
calculations without taking into account the capricious nature of true veins. 
Hence it ap])ears, — 1st, that the vein-fissures have been formed in this district 
almost solely in planes conformable to those of stratification, and that, after 
having been filled with carbonate of iron, quartz, &c., they have been more or 
less disturbed. 
2ndly. That the sparry ore has been converted, often to a great depth, into 
Goethite or pure hydrous peroxide, the consequent decrease of bulk giv ing rise to 
the cellular cavities lined with crystals. 
Srdly. That some smaller jjortions have been converted into hoematite, having 
probably passed through the intermediate stage of brown peroxide. 
4thly. The pebbles of ha;matite at the base of the New Red in the adjoining 
district appear to be derived from these lodes, and would indicate their having 
