The Elements of economic geology

Bibliographic data

Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Part V. Mineral fuels

Collection:: Economics Books

COAL AND ITS CLASSIFICATION 265 A1- in 31" - [f= ig ag }=- |]. st 1e at mn |e at 1 3 1 has a less rectangular jointing than bituminous coal, and usually breaks into nodular lumps with curved surfaces. It has usually only from 3 to 5 per cent. of volatile material, and from 93 to 95 per cent. of carbon. Its thermal effi- ciency is from 14,500 to 15,000 B.T.U., which is less than the best bituminous coal owing to loss of heat during its slow kindling. The intense heat generated by its combustion, and freedom from smoke render anthracite especially suit- able for metallurgical and naval purposes, and slow combus- tion stoves. (GRAPHITE The complete removal of the volatile constituents of coal may leave a residue of fixed carbon as coke; where the removal of the volatile matter is due to rock pressure or earth-movements the residue forms graphite, which may occur in beds, veins, or masses. Its main use, owing to its softness and permanent colour, is in “lead ” pencils; fine scales are used as lubricant and polishing material. Graphite may result from the decomposition of inorganic hydrocarbons, but it is often the last stage in the coal series. The chief supplies are from Central Europe, Ceylon, Mada- gascar, and Korea. The price varies usually from 4d. to 8d. per lb. os SECTION II. SAPROPELIC COALS CanneL Coar—Cannel or candle coal is a bituminous coal, composed of sapropel, an organic mud. It varies in lustre from dull to brilliant ; it may be structureless or well-bedded, and it may have a less regular jointing than humic coal. It burns with a bright yellow flame, and is sometimes so rich in volatile matter that it can be ignited by a match. Large splinters were used for lighting houses, and it thus gained its name of candle coal, of which cannel is a modifi- cation. It is often called gas coal owing to its high gas yield; its gas is too smoky to burn with incandescent mantles, and is mainly used for gas enrichment for factories where the vibration is too great for mantles. Most if not all cannel coal has been deposited in water or swamps, and it usually occurs in lenticular patches which may pass into ordinary

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