On the minute structure of a peculiar combustible mineral from the coal-measures of Torbane-hill, near Bathgate, Linlithgowshire / by John Quekett.
- John Thomas Quekett
- Date:
- 1854
Licence: Public Domain Mark
Credit: On the minute structure of a peculiar combustible mineral from the coal-measures of Torbane-hill, near Bathgate, Linlithgowshire / by John Quekett. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
10/42 (page 10)
![when scratched with a knife, the streak is brownish-black in colour, somewhat resembling that of tlie mineral. There is also another variety of coal, termed tlie Black Methil, but in this the streak is black, as in all other coals. Yet the microscopic characters of both these varieties are very similar, and differ in no respect from coals generally. A curious fact, however, I learnt from the chemists in Edinburgh, that the composition of the Brown Methil came nearer to that of the Torbane-hill mineral than any of the other known coals did ; a fact which is borne out by the similarity in their external appearance. Examination of Coal by the Microscope.—If a small cubical block of any kind of coal be examined under a power of 50 diameters, four of its six sides will exhibit more or less of a fibrous structure, precisely like that of wood ; the other two sides, if perfectly flat, will appear bright and polished, and show very little structure: these correspond to the transverse sections of wood. Treat the Torbane-hill mineral in the same way, and how very different are the results! Nearly the same structure will be found on all its sides, but in none is there the least trace of a fibrous arrangement. Examination of Sections of Coal by the Microscope.—If a section of any well-known coal, cannel or otherwise, be reduced sufficiently thin to be transparent, a work sometimes of considerable labour and difficulty, it will be found to ex- hibit one of two structures, according to the direction in which the section has been made. These, for the sake of distinction, may be called the cellular and the fibrous; the first corre- sponding with a horizontal section, the second with a vertical section, of wood. If it so happen that a section taken at random from any specimen of coal should exhibit one of these structures above named, by cutting at right angles, the other will be found. Thus, for instance, if the first sec tion should correspond to a horizontal section of wood, the cut at right angles to it will correspond with the vertical one ; and, of course, if the section be an oblique one, an intermediate structure would be observed. This remarkable fact is con- stant in all the coals I have examined, and a knowledge of it enables the observer to tell at once whether any section taken at random was a horizontal or a vertical one. How strangely different this from the Torbane-hill mineral! Cut that mineral in any way you ])lease, and there will be little or no difference in appearance. The structure of the transverse sections of coal is so very peculiar and so characteristic, that I must briefly point out the means it affords of distinguishing coal from any other modification of vegetable tissue. The peculiarity con- sists in this,—that, in the midst of a black opaque ground,](https://iiif.wellcomecollection.org/image/b22285416_0012.jp2/full/800%2C/0/default.jpg)
