132 



Revieius and Notices of Boohs. 



lignite. The last two columns of the table give, the one the Ash, 

 the other the Coke, yielded by each specimen. 





Carbon. 



p 



. Nitrogen. 



Sulphur. 



Oxygen. 



Ash. 



Coke. 



Antliracite, Wales . . . 



91-44 



3-36 



0-21 



0-79 



2-58 



1-52 



92-20 j 



Coking Coal, Newcastle . 



81-41 



5-83 



2-05 



0-75 



7-90 



2-07 



66-70 



Cannel Coal, Wigau . . 



80'07 



5-53 



2-12 



1-50 



8-09 



2-70 



60-36 



Coal, ■Wolverhampton . . 



78-57 



5-29 



1-84 



0-39 



12-88 



10-30 



57-21 



Wallsend Coal, Elgin . . 



76-09 



5-22 



1-41 



1-53 



5-05 



10-70 



68-40 



St Helen's Coal, Lancashire 



75-80 



5-21 



1-92 



0-90 



11-89 



5-17 



65-50 



Methill Brown Coal . . 



65-96 



7-78 



0-96 



0-75 



9-23 



15-32 





" All these coals but the first include a considerable amount 

 of bitumen, whose principal constituents are carbon and hydrogen ; 

 and this, when exposed to an elevated heat in cast-iron or fireclay 

 tubes, called retorts, is resolved into coke, which remains in the 

 retorts, and various volatile products, which are expelled ; these 

 latter being tar, an ammoniacal liquid called gas liquor, and a 

 mixture of various gases. 



The tar and gas liquor are by a reduction of their temperature 

 condensed, and the gas, after having undergone a certain process 

 of purification, is conducted into the gasometer, from whence, by a 

 regulated pressure, it is transmitted through metal pipes to the 

 various points at which it is to be consumed. The retorts used 

 in the process are usually 7 feet in length and about 1 foot in 

 diameter, the cross section being, not a circle, but an ellipse. 

 Five of them are usually set in the same furnace, and, when suffi- 

 ciently heated, each is charged with 150 lbs. of coal. It takes 

 from four to five hours to work off" this charge, and the products 

 per cent, are the following, being the means of four experiments 

 by Mr Barlow on the Pelton main Newcastle coal : — 



lbs, per ton. 



Gas .... 475-0 21-20 



Coke .... 1540-0 68-75 



Tar . . . . 112-5 502 



Gas Liquor . . 112-5 5-03 



2240 0 100-00 



The specific gravity of the gas was 0-653, and its volume from 

 1 ton of coal, 9500 cubic feet; or 4 '24 cubic feet for every pound 

 of coal. 



" The crude aeriform product, as has been already stated, is not 



