418 



THE GEOLOGIST. 



but cannot be used as fuel. Externally tliey much resemble the better 

 qualities of Bo^jhead and Torbane Hill mineral, but they yield only about 

 15 per cent, of light oil on slow distillation. They contain 60 per cent, of 

 ash, and some water. The schists and coal both vary in thickness, and 

 occasionally seem to pass into each other. The schists are in some places 

 30 to 40 feet thick, but they do not extend far in any direction, or at least 

 if they extend under the coal, which seems probable, they are not every- 

 where bituminous. 



The Feymoreau schists agree with the rich hydrocarbon minerals of 

 Torbane Hill and Boghead, in Scotland, in appearance, geological position, 

 and in the fact that they occasionally alternate with coal. They differ in 

 being far less rich in useful products, and they are always and readily dis- 

 tinguishable as schists, never putting on the appearance of true coal. 



On the other side of France is Autun, where there is also a small coal- 

 field ; but where bituminous schists of precisely the same nature as those 

 at Feymoreau generally occur in a part of the carboniferous series consi- 

 siderably above the highest coal-seam, and several hundred yards above 

 any workable bed. Below the coal at Autun are coarse grits of granite and 

 gneiss, alternating with black sliales. 



The bituminous shales are partly quarried, and partly obtained by drifts 

 or headings reaching the more valuable beds. There are about ten feet of 

 bituminous schist at Cordesse, where I visited the operations of mining 

 and manufacture ; and of these five only are valuable. Elsewhere the 

 thickness is greater. The broken schist is black ; but at the surface, while 

 in the bed, it is reddish-brown. The percentage of bitumen is very variable, 

 sometimes amounting to 50 per cent, of oils of all kinds, but the average 

 not much exceeding 6 at Cordesse, though much higher at Igornay, a place 

 in the neighbourhood where there are also works. At Chamboy, the rich 

 shales are nearer the coal and alternate with it. A grey limestone and 

 grey ironstone occur in some parts of the Autun coal-field. 



The Autun mineral oils are moderately rich in paraffiue. The shales will 

 not serve as a fuel, and are never so employed. Some beds are rather py- 

 ritous, and others abound with vegetable impressions, differing in this re- 

 spect from the Feymoreau schist. The general resemblance of the Autun 

 specimens to Boghead is very striking. 



^ The manufacture of schist oils and paraffine candles is carried on exten- 

 sively in more than one place near Autun, and the quantity supplied is 

 large. The methods adopted are the same as those of Mr. Young in ge- 

 neral principle, and are said to have been little altered for twenty years. 



The Tertiary shales below the brown coal on the Ehine are found in many 

 places to be very bituminous. They have no resemblance to coal or brown 

 coal, and are easily distinguished from the latter. They are thin, and form 

 the hldtte, or paper coal, of the Germans. They are worked near Linz and 

 elsewhere, and are distilled at Beul, opposite Bonn, the products being 

 precisely similar to those obtained from the other bituminous schists, and 

 in nearly the same proportions ; but the yield is small. 



The Posidonia schists of the Upper Lias are worked at present for eco- 

 nomic purposes at Bamberg, in the north of Bavaria, and at Eeutlingen, 

 near Tiibingen, in Wiirtemberg. The manufacture of light paraffine oil, 

 heavy oils for burning, lubricating oil, and paraffine, has "been carried on 

 with some success by the distillation of these schists for some years. Ee- 

 ccntly a similar establishment has commenced work with the schists of si- 

 milar age at Orawicza in Hungary, near the Danube at Baziasch. 



The Eisleben shales, amongst which the copper slate is deposited, are 

 not less remarkable for their titumen. This is apparently very intimately 



