May 18, 1917. THE COLLIERY GUARDIAN. 943 distinctly uncommon among carboniferous plants. Resins in the widest sense of the term have doubtless played an important part as constituents of coal, but to assume that all those parts of the mineral, which can be shown from their relations to have passed through a liquid phase, are resins of any kind, still more that they are actual resinous secretions, is to prejudice fatally the whole question of the true chemical constitution of coal. In conclusion, a very brief statement may be made regarding the possibility of classifying coals on the basis of their microscopic structure. There would seem to be little doubt that in due course a satisfactory classification, which will link up the past history and present qualities of different coals, would be made possible by that means. As yet, however, we are far from possessing the necessary mass of observations. It is, perhaps, justifiable at this stage to classify coals into the following groups: — (1) Humic coals. In this type, “ lignitoid ” con- stituents predominate, and are, as a rule, of medium depth of colour. Partings of “mother-of-coal” are © Fig. 1.—Map Plan Showing Topography of the Locality. fairly frequent. The oval or flocculent bodies are not uncommon, spore coats are relatively scarce, and “ algae ” are absent. (2). Canneloid, including true cannels and spore coals. The two dominant constituents are pale coloured spore coats and dark or even opaque finely comminuted matrix. Lignitoid lenticles of appreci- able size are subordinate in quantity. “ Mother-of- coal ” is less frequent. “Algae” may be present; when these bodies increased in quantity, the type passed into the following description. THE FUSED SILICA INDUSTRY. In a recent lecture to the members of the New- castle section of the Society of Chemical Industry, Dr. Bottomley, who discoursed on the growth and potentialities of the fused silica industry, stated that the manufactured substance was unattacked by prac- tically all acids except hydrofluoric acid and phosphoric acid over 400 degs. Cent., and, at the same time, having a very small coefficient of expansion—a rod 1 m. long, heated from 0 to 1,000 degs. Cent., expanded only 0-5 mm.—was able to resist extreme changes of tem- perature without cracking. These properties made it of great value for the manufacture of chemical plant. At the outbreak of war, we got most of our refractory and acid-proof material from Germany, and there was a serious shortage in consequence. Fused silica was able, to some extent, to make good the deficiency, and had played a considerable part in equipping the numerous factories which had been erected for our- selves and our Allies for the manufacture of explo- sives, especially in connection with the concentration of sulphuric acid and the condensation of nitric acid. For example, a large proportion of the nitric acid plants in this country had been fitted with Vitreosil condenser and conduit pipes, and they had also been able to supply our Allies in France, Russia, Italy, and Roumania with such plants. Fused silica had also been used in the de-nitration of mixed acid from the manufacture of T.N.T., in the manufacture of hydro- chloric acid, and in the construction of basins, etc., for concentrating phosphoric acid. To put it generally, fused silica was of value in all cases in which heat the syndicate’s wares were concerned. He spoke in high terms of the quality of the fused silica, and declared that, so far as his firm’s nitric acid condensers were concerned, they had never had a solitary fracture over a period of four years. THE ROPEWAY INSTALLATIONS OF THE BLAENAV0N COMPANY, SOUTH WALES. By George Frederick Zimmer, A.M.Inst.O.E. The ropeway, though one of the most economical means of transporting material mechanically, is some- how not often met with in this country, and the instal- lations described in our technical literature deal mostly with plant erected abroad. It is therefore encouraging to find that the enterprising colliery establishment of the Blaenavon Company has been sufficiently far-sighted to adopt this means of convey- ing by investing in three distinct ropeways at their colliery establishments. These installations are of particular interest, as every one of them is for a different object, requiring specific peculiarities for distinctive purposes, and yet every one is an unquali- fied success. On the map plan (fig. 1) showing the topography of the neighbourhood, the three ropeway installations are indicated by straight lines between the points A—B, C—D, and C—E. The objects of these ropeway instal- lations are to establish effectual communications between the company’s coal pits, washery, and coke oven plant, which are scattered over a considerable area. The installations were all designed, built, and erected by Ropeways Limited, and all three are on different systems, so that each will conform in the best way to one of the three purposes for which they were erected. The first of the ropeways, between the points A and B (see figs. 2 and 3), is on the ordinary mono-cable system; while the second, between points C and D (see fig. 4), is on the bi-cable system; and the third, which is for the disposal of pit rubbish, is again on the mono- cable system (see fig. 5), but so designed that the buckets may be tipped at any predetermined point on the line—a feature which constitutes a new departure in the practice of building mono-cableways, as for- merly installations for the formation of spoil banks were generally on the bi-cable system. The first ropeway is loaded at the Milfraen Colliery at point A on plan, and discharges at the Kay’s slope screens at point B (fig. 2 shows this line). As the collieries are situated on the western side of the rail- way, the run-of-mine coal is handled from there by a conveyor, which passes underneath the railway, and is discharged at the eastern side into a large ferro-con- crete bunker, round which the terminal plant of the ropeway is built. The length of this ropeway is 1,280 Fig 2.—Between Points A and B, Milfraen to Kay’s Slope. Fig. 3.—Ropeway Crossing L. & N.W. Railway, Line A—-B, Milfraen to Kay’s Slope. (3) Bogheads. There very pale coloured “ algse ” form the principal and sometimes almost exclusive con- stituents, as in torbanite and kerosene shales. A matrix, like that of the cannels, may be present in varying amount, as also may spore coats and patches of “bituminous” material. Of these three types, the first is so named by I’otonie, while the second and third form his sapropelic group. It should be observed particularly that the above classification has no direct relation to the grouping of coals according to their carbon content into “ bitu- minous,” “steam,” and “anthracite” grades. The evidence so far obtained from the microscopic exami- nation of coals is decidedly against the theory that the varieties of coal just indicated are due to differences in the nature of the original constituents, and therefore favour the alternative hypothesis that differences of that kind are the result of varying degrees or varying modes of alteration. The main business of the micro- scopist is to analyse those many varied qualities of coals, which are the result of original differences of constitution; the investigation of the modifications produced by subsequent changes—seen most conspicu- ously in the varying carbon content, and the qualities associated with it—must for the most part be the work of the chemist. The entrance examinations for students at the French School of Mines and the schools for master miners at Alais and Douai will not be held this year. resisting and acid proof qualities were of importance, and was now very largely used fpi’ laboratory articles of all sorts, especially for combustion tubes in deter- mining carbon in steel, pyrometric work, etc. He advocated its use in the gas industry, as, on account of its resistance of high temperatures, it was possible to make all gas lighting cylinders and globes of fused silica much smaller than could be done with glass, thereby enabling a high mantle temperature to be employed, and a corresponding increase of light obtained. It was already being largely used for elec- tric heating apparatus, and, on account of its valuable insulating properties, which were retained at relatively high temperatures, and of the fact that it was not hygroscopic in the same way as glass and china, it made a very efficient insulator. Mr. Henry Peile, of the Priestman Collieries Limited, who presided, praised the specimens of fused silica exhibited by Dr. Bottomley, and said the exhibits were most wonderful, very complete, and most beauti- fully finished. It showed very great enterprise and very great skill on the part of those connected with this industry to have been able to develop it as it had been developed during the last few years. Mr. A. Trobridge, nitric acid manufacturer, eulo- gised the way in which the Thermal Syndicate had stepped into the breach in a time of national necessity, and jocularly complained that the syndicate improved its manufactures so quickly that it was difficult for a nitric acid manufacturer to keep up-to-date, so far as yds., and its carrying capacity is 35 tons per hour, the individual loads being 7 cwt. each. There is a fall of 63 yds. in favour of the load between the receiving and delivery points, so that only very little power (between 3 and 4 horse-power) is necessary to drive this complete installation. The ropeway passes ovei’ the London and North-Western line just before it reaches the unloading terminal (see fig. 3). The coal is here screened, and the small from the screens is dropped into railway trucks at point B, and shunted down to the new washery at point C, where their con- tents are dumped into an elevator, which delivers in its turn to the washing machinery. After the coal is washed, it is loaded on to the second ropeway, and transported to point D, where it is automatically tipped into a ferro-concrete bunker of 1,200 tons capacity, over a battery of coke ovens, to be converted into coke. The slack from the washery is loaded on to the third ropeway, from which it is dumped between the points C and E (sec photographic view, fig. 4; and diagram, fig. 5). The second ropeway, between the washery and the bunkers at the coke ovens, is on the bi-cable system ; the length between the terminals is 720 yds., and the caoacity 100 tons per hour, which is handled in indi- vidual net loads of 17 cwt. each. There is a slight adverse rise of 6 yds. between loading and unloading points; the driving power required is therefore some- what higher, viz., 17 b.h.p. The driving and tension arrangements are situated at the loading end, which