702 



COAL. 



(<ML 



cubical. The lamellated structure, or what is termed the 

 reed of the coal, ii always parallel to the bed or trata 

 upon which it reitl, at is the general case of all coals, 

 with a very few exceptions. -Of this coal there are two 

 kinds, the caking coal, and the open burning coal. The 

 caking coal of the best kinds, however small when kind- 

 led, undergoes a semi-fusion, and unites into a solid mass. 

 The open burning coal, burns more rapidly than I lie 

 former, with much flame and heat ; the caking coal is 

 very abundant in England, the other in abundant both 

 in England and Scotland. The cubical coals which 

 unite when set on fire, are known by the name of caking 

 or smithy coals ; the open burning coals by the name of 

 rough coal, cheery coal, and clod coal. 



The Whitehiven caking coals, in the west of Eng- 

 land, according to Kirwan, contain 



Carbon, 56.8 



Asphalt and Maltha, the former pre- 

 dominating, 43 



9O8 



Specific gravity 1.250. 



iUiecoal. 2. Slate Coal Is black, compact, and much harder 

 than the Grit specie* ; dull in the colour ; in working 

 turns out in large quadrangular masses, which can wth 

 ease be split into very thin pieces, similar to slates, hence 

 the nair.e. This coal is open burning, and produces much 

 flame and smoke ; it contains a greater proportion of white 

 ashes than the cubical coals. Some of the inferior kinds 

 of this coal burn with difficulty, and produce a great 

 quantity of white ashes. This coal is commonly known 

 by the name of splint coal, and, according to Kirwan, 

 contain* 



Carbon 47.6 



Maltha 31.6 



Ashes 20.8 



100.0 



Specific gravity 1.426. 



3. Glance Coat Is black, with bright metallic lustre, 

 and brittle ; it has the external characters of the preceding 

 species of coals, but the chemical properties of charcoal, 

 hence termed by some mineralogists native mineral carbon. 

 It burns with considerable heat, with a blue lambent 

 flame, produces no smoke, and leaves a small proportion 

 of ashes ; it appears to have a portion of sulphur in di- 

 rect combination, so that in burning it gives out a most 

 suffocating effluvia, it produces no soot, but on the con- 

 trary whitens the plai.es where the fumes are condensed. 

 This kind of coal abounds in Ireland, and is known by 

 the name of Kilkenny coal ; it is the blind coal of Scot- 

 land, and the malting, or stone coal of Wales. This coal 

 approximates to the graphite or plumbago species, and in 

 some instances passes into it. From the trial of several 

 specimens, it contains of carbon from 72.05 to 90.00. 

 Specific gravity, 1.526. 



4. Canncl Coal Is black, with little lustre ; in work- 

 ing turns out four-sided columnar, breaks with a con- 

 choidal fracture, in any direction, like pitch, ignites very 

 easily, and burns with a very bright flame like a candle, 

 from which itjderives its name. It is found very abundant 

 in the coal field at Wigan, in Lancashire, where there is 

 an entire stratum of it about four feet thick, without a mix- 

 ture of any other coal. It produces very little dust in work- 

 ing, and does not soil the fingers as the other coals do ; varie- 

 ties of this coal are found in Scotland, forming frequently 

 part of the thickness of the common coal*. What is termed 

 pitch coal by some mineralogists, is only a variety of this 

 species. The cannel coal, when first kindled, decrepitates 

 very much, throws the burning splinters to a distance, 

 and it on this account dangerous ; it is said that this fault 



<; uice 

 coal. 



Cuutel 

 coal. 



is corrected by immersing the coals for some time in wa- Coil, 

 ter, previous to their being used for fuel. In Scotland v -Y > ' 

 this coal is termed parrot coal, or bottle coal. 

 It contains, according to Kirwan, 



Carbon 7.5. 



Maltha 21.7 



Ashes :(.!_' 



99-82 

 Specific gravity l.J 



5. Sulphureous Coal, is of a dull black colour, mix- Sulphure- 

 ed with a great proportion of pyrites. Though pyrites out t<aL 

 is found in distinct pieces in coal, this occurrence does 



not constitute it a sulphureous coal, because the pyrites 

 can easily be picked out ; but sulphureous coal, proper- 

 ly so called, has the pyrites so interwoven with its tex- 

 ture in small veins, or so intimately combined with the 

 principles of the coal, that the sulphureous parts cannot 

 be separated. It is very unsafe to work such coals, be- 

 cause if any quantity of the small coals produced in 

 working is left below ground, a decomposition ensues, 

 heat is generated, and the mine is set on fire, of which 

 there have been many instances. When laid in heaps 

 above ground the same result ensues, hence it is very un- 

 safe to be put on board a vessel for a voyage of any 

 considerable length. 



This coal is very heavy, and yields a large proportion 

 of ashes. 



6. Culm Coal, is of a dull black colour, small and Culm coal, 

 dusty, by some mineralogists it is reckoned a distinct 



kind of coal, at least such is said to be the case in Sweden. 

 What is termed culm in Great Britain, is the refuse or 

 small dusty coal produced in working the common coals; 

 it contains much earthy matter, will not kindle in an or- 

 dinary fire place, but produces a considerable heat and 

 flame in a furnace, where a strong current of air is intro- 

 duced ; it also produces a very great proportion of ash- 

 es. In England it is exempted from the high duty im- 

 posed on the "ther coals. 



7. Bovey coal, or bituminous wood, is found in allu- BoveyeoaL 

 vial land, though some mineralogists affirm that it is 



found in the rock stratification. It is composed of trees, 

 reeds, and rushes embedded in the alluvial earth, the 

 form of the^trces, the ligneous and fibrous texture, being, 

 in most cases, distinct ; their texture is impregnated 

 with petroleum, and combinations of the sulphuric acid. 

 When first dug up, the fibres are flexile ; in burning, it 

 produces little heat, and a very unpleasant smell, and is 

 only used where other kind of fuel is scarce and 

 in high price. In England it is found in greatest abun- 

 dance at Bovey near Exeter, from which it derives its 

 name ; it also abounds in many parts of the continent, 

 particularly in Germany. 



Two hundred grains of Bovey coal, according to Hat- 

 chett, yielded, 



Water turbid and mixi'd withl /v, 



bitumen j 6 



Thick brown oily bitumen . . 21 



Charcoal 90 



Hydrogen gas, carbonated hy- ' 

 drogen, and carbonic acid 



200 



According to Professor Jameson there are five sub- 

 species of this inflammable matter, classed under the name 

 of Ilitiini coal. 



The fon going are the principal kinds of coal known 

 in commerce, ana used for economical purposes, in each 

 kind various shades of difference exist, both with respect 

 to texture and quality. 



With regard to the economical uses of the coals b- 



