316 FOSSIL FLORA 



trolling and directing the powers of steam and of the electric fluid, 

 it may be hoped that science, impelled onward by humanity, will 

 ultimately be able to bring the carburetted hydrogen from the mine, 

 where it spreads misery and death, and, conducting it into proper 

 receivers, to apply it to economical purposes. Already something 

 has been accomplished. The floor of the Bensham seam in Hebburn 

 Colliery was observed to rise, and gas to escape from another seam 

 24 feet below ; the lower seam was tapped, and the gas is conducted 

 by a pipe to the subterranean stables and used to light them. At 

 Wallsend a large quantity of gas — 11,000 hogsheads per minute — is 

 now wasted ; it is brought up by a pipe from the depth of 900 feet, 

 is ignited above ground, and may be seen from a distance of several 

 miles burning like a huge bonfire. The Americans, ever ready to 

 make practical apphcations, " are wiser in their generation." There 

 is an abundant discharge of the same gas, from carbonaceous shales 

 connected with the coal formation, at Franconia, but its escape into 

 the atmosphere is arrested, and it now illuminates the streets and 

 houses of the village. 



Pressure, heat, and time have been additional means of completing 

 the conversion of wood into coal. 



The A'cgetable deposits of our district have been compressed by an 

 enormous weight of superincumbent rocks, consisting of the broken- 

 up masses of more ancient mountains, of sand, mud, and lime beds of 

 great thickness, and of lava streams poured out from the depths of 

 the earth. 



Experiments made by Professor Goppert, and also by Mr. Oakes, 

 have well shown the influence of heat. The former placed recent 

 plants, representatives of the fossil Flora, for a long time in water, 

 whose temperature was maintained during the day at 212° Fahr. and 

 at from 133° to 167° Fahr. during the night ; in two years a product 

 was obtained which could not be distinguished from brown coal. It 

 was not, however, black and shining like ordinary mineral coal, but 

 by the addition of a small quantity of sulphate of iron, the product 

 obtained had this aspect. Anthracite can be formed by artificial 

 means, for Mr. Oakes exposed the bituminous coal of Alfreton to a 

 very gradual heat, and the result was, not coke, but an anthracite, 

 similar to that which is natural. Probably the lowei' beds of the 

 Welsh coal basin are anthracitic, because they are nearer to the 

 sources of central heat than the upper beds, which are bituminous. 

 Basaltic and other igneous dikes and overflows produce a like effect ; 

 many instances occur in the Scotch coal-fields ; and at Calton Hill, 

 fragments of coal which have been enclosed in the trap rock are 

 changed into anthracite. Our own district also presents facts of the 

 same nature. A large basaltic dike cuts through the Carboniferous 

 beds at Beadnel, and the coal at the point of contact with the dike 

 is charred, forming a kind of coke, but, at a short distance, it is 

 anthracitic, the hydrogen and oxygen of the coal havmg been driven 

 off along with a smaller amount of carbon, by the heat of the 

 molten rock. 



Time is demanded to account for the accumulation of vegetable 



