July 16, 1915. THE COLLIERY GUARDIAN 115 _______ ___________________________________________________________________ The Microscopical Examination of Coal.* By JAMES LOMAX. (Continued from page 66.) Regarding the shallow seam from the two localities, Brereton and Walsall, there is a close agreement in their constituents, although in the Walsall area there is a greater abundance of the lycopodaceous remains than in the Brereton seam. Both have, as already mentioned, commenced with a soft bright and brittle coal, break- ing up into more or less cubical fragments (dice). Micro-sections from this region show each to be com- posed of similar plant remains, which have been derived from very small and delicate plants, such as ferns, small Equisetinae (calamites), and others of a like nature belonging to the Archegoniate order of plants. Such plant remains would naturally form a fine humus, showing on carbonisation few laminations in comparison to those parts derived from stronger and larger plants, this, of course, forming the bright brittle coal found so general at the base of almost all seams. As already pointed out in the first lecture on the Rugeley seam (see in the coal. The stem is cut through almost in the centre, showing both the pith cavity A, the two sides of the woody cylinder B, and the medullary rays C, which gives to most woods the cross hatching, or grain. It is probably a species of calamite, or young stem of mesoxylon, a species of cordaites. Much larger stems are to be found, some having the wood tissues preserved either on the outer or inner part of the stem, which may gradually become jet-like, or may, as seen in many sections, be carbonised or converted into charcoal or mother of coal. This will be seen in fig. 13, which is a photograph (natural size) of a section containing such fragments of wood tissues. In the majority of eases the carbonised woody tissues found in thin partings is the remains of the cortical (bark) layers of the carboni- ferous trees which would be stripped or shed naturally at more or less equal intervals. Both the Rugeley and Walsall seams show this in the regular soft charcoal-like partings. Besides stems, root tissues are to be found in both seams. These are mostly belonging to the lyco- is found chiefly is the bole of the tree with the root stock attached, which ascends into the roof forming a pot-hole, whilst the root stock is embedded in the coal beneath. From each root stock there are four primary roots given off, these again dividing or bifurcating into two, these again dividing as before according to the size and growth of the tree above. Generally there are found eight secondary roots attached, which spread out a considerable distance from the main roots. Similar secondary roots may be found in the seat earth, beneath the coal. Now, what has occurred, as already pointed out, is that most of the lycopodaceous trees have com- menced their growth after there has been deposited a certain thickness of vegetable debris for their sustenance. The secondary roots grow and ramify in all directions in the vegetable humus and soil beneath. All stigmarian roots have been clothed with numerous rootlets, origin- ally round, but now found as black ribbon-like streaks Fig. 5.—Laminated coal. A Fig. 6.—Laminae with leaves of cordaites (vertical). Fig. 7.—Cordaites leaves (horizontal). Fig. 8.—Resinous laminae (ovalites). Rugeley Seam (vertical). J ! U J-f $ > , ■ 'll ■ j.l Fig. 14.—Horizontal section, showing stigmarian rootlets in a ground mass of fine humus. The rootlets are cut more or less tangentially, the outer epidermal tissues being well preserved. Walsall seam. - - * J ■ . .. w Fig. 9.—Resin us bodies, Walsall Wood Seam (horizontal). Fig. 10.—Wood tissues, probably that of a cordaites, cut transversely (vertical). He Wa i. i.r ? 4V \ \ \ U • - ■ Fig. 13.—Carbonised wood tissues in a ground mass of resinous matter and spores, Walsall seam, (horizontal section). Figs. 5 to 10.—Horizontal and Vertical Sections of Coal Samples. Colliery Guardian, January 8, 1915, p. 76), as we ascend higher in the seam the coal becomes more lami- nated, the laminations being composed more or less of alternating bands of leaf tissues and resinous bodies, with a small percentage of microspores and megaspores. Fig. 5 shows a photo of a vertical section cut through such a region, 3 to 7 in. from the base of the Walsall seam, the lower part showing fine humic coal or dice, A, and the upper part alternating bands of bright and dull looking coal, B. At the point C there is a thin laminee of very small megaspores, and a little below a band of resinous bodies, D. Fig. 6 is a photograph taken to show the leaf laminae cut vertically; whilst fig. 7 is of similar laminae cut horizontally, showing the tissues of a cordaites leaf. The resinous bodies, as seen in fig. 5, may vary in thickness and extent in the same seam. Some samples may contain a large quantity, whilst others taken only a few feet away may contain few; also the size may differ, some being very large and others small. Fig. 8 is from a vertical section from the Rugeley seam, cut from a similar band to D in fig. 5, showing the resinous bodies to be of a small size. Fig. 9 is from the same horizon in the Walsall seam, showing them to be of a comparatively large size. Coal composed of like constituents to the above may extend throughout the whole thickness of a seam, or it may be replaced by a spore coal, very low down in the seam. Sometimes also the resinous bodies are in such large quantities that the colour of the coal is a dull grey black to brown, and rough in texture; often such bands contain fragmentary wood tissues and earthy matter in varying quantities, also megaspores and microspores. Such bands or lamin® are classed as “ spires.” Many such bands can be found in some seams at regular intervals, whilst in others they are very scarce. Fig. 10 is from a similar band in the Walsall seam. In it can be found good wood tissues in a ground mass of finely divided resinous matter. Fig. 11, also from the Walsall seam, shows another band containing a large amount of earthy matter. The writer has, in former papers, referred to “ jetonised ” wood tissues. This means wood tissues in coal like jet. Such coal is very lustrous, and will take a very high polish. It is of various thickness, and mostly in lenticular patches. It is found that both in the Walsall and Rugeley seams such tissues are very common, and, in many cases, represent small twigs, portions of large and small stems. Fig. 12 is a photograph of a piece of stem which is lying horizontally * A lecture read before the South Staffordshire and War- wickshire Institute of Mining Engineers. Fig. 12.—Long section (vertical) of a small stem cut radically, showing the pith cavity, the two sides of the woody cylinder B and the Medullary rays C, Walsall seam. B AB Fig. 11. —Spires consisting of numerous small resinous bodies with a few megaspores and earthy matter, Walsall seam (vertical). pods. The characteristic root stock of this order is the Stigmaria, there being many species, some of a high size, others small, according to the species of the stem to which they belong. The writer has taken very particular notice as to the position of various specimens he has come across in the coal substance itself. He finds that it is rare that a stigmarian root stock passes right through the seam into the seat earth below; when it does it mostly occurs when there is a little or thin seam of coal in the floor beneath the main seam. What in the seat earth or roof, shales and mudstones. Such rootlets can be found in the coal itself, showing that the rootlets have grown in the vegetable debris, as already stated above. Fig. 14 is from the Walsall seam, show- ing stigmarian rootlets with the tissues preserved. Both in the Rugeley and Walsall seams such rootlets are common. (To continued.) ____________________________ Iron and Steel Imports and Exports.—-During the first half of 1915, 100,581 tons of pig and puddled iron were imported into the United Kingdom, the corresponding quantity imported in 1914 being 123,222 tons; the value rose from £493,860 to £539,880. The total quantity of iron and steel and manufactures thereof imported amounted to 511,012 tons, valued at £4,177,263, as compared with 1,170,989 tons, valued at £7,602.460. The principal declines were in wrought iron, hoops and strips, plates, rails, sheet bars, and tinplate bars (3,799 tons, as against 226,080 tons), steel castings and forgings, bars, angles, etc., girders, beams, joists, and pillars. It is significant that the import of steel blooms, billets, and slabs from the United States rose from 18,521 tons to 152,854 tons. In the same period our exports of iron and steel fell from 2,376,264 tons, valued at £25,169,145, to 1,448,502 tons, valued at £17,771,996. The following shows exports of pig iron in the six months :— Quantity. Value. 1914. 1915. 1914. 1915. Tons. Tons. £ £ Sweden................... 45,807... 14,726... 137,965... 66,769 Germany ................. 69,226... — ... 214,407... — Netherlands ............ 36,529... 9,492... 123.353... 32,904 Belgium ................. 33,793... — ... 117,589... — France ................... 70,780... 25,862... 236,995... 127,688 Italy ..................... 54,832... 22,460... 166,691... 132,535 Japan ................... Sl/SS... 15,048... 118,505... 71,086 United States of America 41,919... 23,029... 305,158...258,066 British East Indies...... 6,426... 4,923... 21,651... 20,764 Australia................. 23,126... 6,951... 67,461... 35,940 Canada................... 8,571... 3,683... 32,362... 31,612 Other countries.......... 83,338... 40,748... 253,088...166,545 ("Basic................. 3,181... 177... 8,953... 605 • | Forge and foundry ...323,863... 95,917... 891.412 ...315,187 s J Haematite ..........128,082... 30,427... 456,003... 146,509 o ] Spiegeleisen, ferro- E"1 I manganese & ferro- L silicon ............. 56.254... 40,401... 438,857...481,608 Total...........511,380...166,922...1,795,225..943,909 Puddled bars........ 574... 979... 3,712... 7.076 Total of pig & puddled iron 511,954 . 167,901.. .1,798,937.. .950,985 The chief decreases were in railroad material (£1,443,539, as against £2,554,935); wire, galvanised sheets (£2,315,064, against £4,713,311); tinned plates and sheets (£2,794,695, against £3,534,851); cast iron pipes and fittings, bolts and nuts, and steel girders, beams, joists, and pillars (£250,700, as against £547,890). The value of steel bars, angles, etc., exported increased from £1,456,864 to £3,092,107, this being entirely due to the large consignments to France, valued at £2,189,249.