Sulphurcous coal is but very little used, being so dan gerous to work ; it is only suitable for the burning of lime, the making of salt, or for producing sulphate of iron.
Culm is used for burning of lime, making. of salt, and for steam engines ; it sells at a very low price. There is but a small consmnpt for this coal, in comparison of what is produced annually in the mines.
Bovey coal is only used as common fuel by the poorer classes of the community, where better fuel cannot be had.
With respect to the origin of coal, naturalists have in general concluded that it is from the vegetable kingdom, particularly from the result yielded by distillation, which is as follows:— Watery phlegm, Volatile oil, Volatile alkali, Thick oil, which last, on being rectified, produces a transparent thin oil ; but it is remarkable that this oil, by exposure to the air, becomes black like animal oils.
Various theories have been brought forward regard ing the formation of coal, and in these much learning and ingenuity have been displayed. From the incontestible and evident traces of vegetables found so very abundant ly in the strata of the coal fields, together with the above analysis of coal, and the strong light and heat evolved in burning, the arc inclined to concur in idea with those who conceive it to be of v egetable origin. All the pa tient investigation of mankind regarding this point of na tural histoiv will never produce an absolute and conclusion on the subject, there beg such incur- mountable difficulties, particularly w hen etc cohsider that many of the vegetable remains found in the coal strata of Great Britain, belong to classes of plants which arc now found only to exist in the equatorial regions ; a fact which favours a theory brought forward by sonic naturalists, viz.
that at the great and universal deluge, the poles of the earth were changed considerably from their position. The formation of our globe, together with the causes which produced the various convulsions and dislocations which have so evidently taken place in the mineral king dom, must ever remain veiled in a (lark impe.ne.trahle. cloud. We must, however, conclude, that this vast ma gazine of fuel is most evidently placed by an all-wise Being in the bowels of the earth, in such positions and situations as are most apt and convenient for the use of man, and where his industry and ingenuity may be ex ercised.
Coal being an article so indispensibly requisite for mankind in civilized society, it is of great importance to learn every particular regarding its natural history, so that its existence may be traced, by a distinct analogy, in countries widely separated. And when coals are found, it is also very important that the most approved practi cal and ceconomical plans may be applied for working them to the best advantage. The mode of searching and boring for coal ; the detail of the most approved plans now used for working the mines ; descriptions of the dislocations and obstructions which most frequently oc cur in coal fields ; together with the general economy connected with the working of coal mines, will be given under the article AltNE. (R. R.)