August 18, 1916. THE COLLIERY GUARDIAN. 303 consequent dislocation and crushing of strata to allow of its permeation. Ducks Nest Colliery in olden times, and Lower Vobster more recently, have always had the reputation of being the most gaseous workings in England; both are situated nearest the dyke, and in the bend of the overthrow7. Lower Vobster has a peculiar history of its own. When the eruptive dyke was in action it uplifted and turned over the strata, as described, and in forcing a wider opening for the eruption, the opening expanded like a fan, the east flank of the moving strata being moved over to the east side of the great Clandown fault. These coal strata and the vertical limestone at Soho Quarry owe their situation to that movement, and were part of the bend of the turnover; and, being moved over to the east side of the fault, they never subsided with the west side, which has a downthrow of 750 ft. That downthrow was due, first, to the uplifting force of this dyke, when at its greatest, to the level of the Vobster and Soho strata; thereafter plunging to its present depth when the eruptive force ceased. When the eruptive force weakened, the limestone and millstone grit, being far more rigid than coal strata, fell back against the yielding material of the dyke. This falling back of the limestone caused, as it were, a vacuum, in the shape of the letter V, into which vacuum the vertical coal strata of the lower subdivision fell in great confusion. The veins have no claim whatever to stratification, being twisted and contorted into fantas- tical shapes; and the coal was jumbled together in brads, hulks, or pockets — all very gaseous. Lower Vobster Colliery was rich in the quantity and quality of its coal, the seam, main coal or callows, said to be 6 ft. in thickness, being equal to any coal in the kingdom for smith’s or cooking purposes; but it was under three insurmountable difficulties — excessively gaseous, the uncertainty of the hulks and brads of coal; thirdly, with a roof so crushed, that it ran like quick- sand. The Radstock upper seams are known to be gas free. The second, or Farrington Gurney, seams are also free, with the exception of the unfortunate explosion at N orton Hill Colliery. The third, or lower, series have a natural division into an upper and lower group, locally known as the north seams of New- bury and Mackintosh; and south seams, or lower group, whose out crops have been worked by discon- tinued collieries at Lower Vobster, Coal Barton, Duck’s Nest, and numerous others, all in the imme- diate neighbourhood of the igneous dyke, and consequently excessively gaseous. The upper 12 seams at Newbury and Mackintosh were simply lifted over and placed where they now lie, with very little minor dislocation or crushing. The con- sequence of this is that nine of the seams to the north are gas free, while three to the south, or dyke side, are gaseous. This is further evidence to show that coal mine gas is solely due to proximity to heat. If engineering skill in the future should enable the third series of the Radstock coal basin to be tapped, particularly in the section described, the coal would, in all probability, be found to be anthracite, which is bituminous coal baked. In the parishes of Chipping Sodbury and Tate, in Gloucestershire, the land owners or their tenants dig a con- siderable deposit of nodules of white crystal, whose chemical composition is” strontium sulphate, lying immediately under the turf in the keuper marl • of the new red sandstone system. Before the war this mineral was shipped in large quantities at Bristol for Germany, to be used in beet sugar refining. The cause of the presence of the mineral in that parti- cular locality is self-evident. A little to the north, at Charfield-Green, is an igneous dyke, which undoubtedly bears the same relationship to the Gloucestershire coal basin at Goalpit Heath as the dyke in the Mendip range does to the Radstock basin, or the igneous dykes at Woodspring Hill and at Uphill, to the Nailsea coal basin. The Gloucestershire coal basin is very peculiar in shape, long and narrow, possessing all the stratification of the Radstock basin. Its lower coal series must be at an enormous depth, and its coal must undoubtedly be anthracite, the baking process having set free its gaseous constituents as sulphuretted hydrogen and carbon dioxide gases, which, combined with atmospheric oxygen, con- densed to the crystal mineral. German Coal Syndicate. — The German Coal Syndicate seems likely to be renewed for five years from March next, when the present agreement expires. The Government has representatives on the Board, and insists upon having a voice in the fixing of coal prices so that they shall not press too heavily upon the community. The Syndicate might have collapsed last year, but the Government would not allow it, and news from Germany indicates that the Government has now given the trade an intimation that if the Syndicate is not renewed voluntarily it will be done compulsorily. Some of the large consumers—notably the recently-formed combina- tion of the great dye-making firms—are acquiring collieries of their own. THE CONSTITUTION OF COAL.* By’ D. T. Jones and R. V. Wheeler. The general trend of opinion with regard to the pro- bable origin of coal is that the material from which it was formed was essentially vegetable. There is no consensus of opinion as to the manner of formation of coal, probably because attempts have been made to assign a common rationale to all the -varieties, whereas there seems to be no adequate reason why different varieties, or, indeed, different accumulations of similar varieties, should not have -been produced in different ways. The agencies that produced coal from the original (vegetable) substances are gene- rally supposed to be, in the first instance, decay through the agency of bacteria, followed by pressure, heat, and time. The present research is an attempt to determine the chemical character of the main components of “ coal,” which, accepting the usual view as to its vegetable origin, we regard as essentially a conglomerate of cellu- losic and resinic compounds. It has been shownf that these two main constituents of bituminous coals (with which our experiments have mainly dealt) can be separated by means-of solvents. Extraction of the dried coal with pure, dry pyridine brings about a partial separation, leaving an insoluble residue consisting mainly of the cellulosic constituents. Further extraction of the soluble portion (after it has ELECTRIC WINDING IN SOUTH YORKSHIRE. — ' * 51 Is* r f' * L v 1 *1 1 ** r I? F h X •*- * r * ■*d Steel Headgear Construction. been freed from pyridine) with chloroform or benzene yields a soluble portion containing the resinic compounds and an insoluble residue consisting of cellulosic com- pounds resembling in every respect those separated directly from the coal by means of pyridine. The scheme of separation is as follows Bituminous coal (Treatment with pyridine) Insoluble residue (Cellulosic, compounds) A Extract (Treatment with chloro- form) Insoluble residue Extract (Cellulosic compounds) (Resinic compounds) B C That the residue B, insoluble in chloroform, is to be regarded as composed of cellulosic compounds that possess (or acquire during extraction) the property of solubility in pyridine, rather than as resinic compounds that have lost the property of solubility in chloroform, is apparent from the fact that A and B are infusible, whilst C softens at about 100 degs; C on exposure to air undergoes some form of oxidation (exhibited also by resins) which exerts photochemical action on a sensitised plate, whereas A and B have no such action; on dis- tillation in a vacuum A and B yield gaseous mixtures which closely resemble one another both in quantity and composition, and differ markedly in both respects from the gaseous mixtures obtained by distilling C under * From the Transactions of the Chemical Society. f Trans. Chem. Soc., 1913, 103, 1706. like conditions; the liquid distillates from A closely resemble those from B both in quantity and kind, and bear no resemblance to those obtained from C, being small in percentage quantity, and consisting almost entirely of phenols, whereas C loses half its weight at 450degs., as liquid distillates, which contain all the components of tar obtained by the low-temperature carbonisation of coal, with the exception of phenole which are absent. Character and Composition of the Cellulosic Compounds. Boudouard * has shown that unchanged celluloses, if present at all in bituminous coals, can only be present in minute quantities. The cellulosic compounds are degradation products of the original plant celluloses, the extent to which change has taken place being indi- cated by comparison of the ultimate analysis of cellulose with that of either portion A or portion B of a bituminous coal. The most striking point of resemblance between the ” cellulosic compounds,” A or B, separated from coal, and cellulose, is that both yield phenol or phenols on destructive distillation. Wichelhaus j- found that cellu- lose yielded phenol, but homologues of phenol were not obtained. In the ease of the cellulosic compounds in coal, analyses of the phenols obtained on distillation show a composition ranging between that of the cresols and the xylenols. The production of phenols on destructive distillation is occasioned by the presence of the furan grouping, in the substance distilled. This grouping is stable, survives the degradation changes to which the cellulose molecule has beensubjected, these changes bringing about the elimina- tion of hydroxyl groups and hydrogen, with the conse- quent formation of oxide or ether groupings. There is thus reason to believe that the compounds constituting the cellulosic constituents of coal may not comprise many tpyes. This suggestion is borne out by the fact that A and B classes of cellulosic compounds yield, on distillation below 450 degs., gaseous and liquid products almost identical in composition. The readily decomposable portions of the cellulosic compounds A and B thus closely resemble one another in constitution, and the same may be true of the more stable portions. The question arises whether in some of the cellulosic derivatives the characteristics of the cellulose grouping may not have disappeared entirely and molecules approximating in structure to that of carbon have resulted. “ Free ” Carbon in Coal. The idea seems to be widespread that most coals contain a certain proportion of free carbon, and the difference between one class of coal and another, between bituminous and anthracitic coals, for example, has been ascribed to a difference in the proportion of free carbon present. This view appears to be maintained largely on account of the colour and. general appearance en masse of coal, which become more carbon-like the older the coal measure, and from the knowledge that the parent substance of coal has been subjected to various degrees of molecular attrition, involving the loss of hydrogen and oxygen, which, it is supposed, may have been sufficient in the case of some components to have effected complete carbonisation. The argument respecting the colour of coal may be answered by pointing out that the portions of coal insoluble in pyridine and chloroform are indistinguish- able in appearance from Cross and Bevan’s dehydrated cellulose (“ pseudo-carbon ”), a carbon-like substance which contains no free carbon.J The agencies that have in the course of time produced coal, presumably from vegetable matter, are bacterial decay, heat, and pressure. Excluding as highly impro- bable the possibility of micro-organisms having effected a segregation of free carbon, there remains for considera- tion the influence of heat and pressure. It is doubtful whether any coal seam has, in the normal course of events, attained a temperature as high as 300 degs. Below this temperature every variety of distillate ordinarily found in coal tar begins to make its appearance, and these compounds in an uncombined state are not normally present in coal. -There are isolated instances of the occurrence of paraffin waxes oozing from coal seams, usually in the neighbourhood of a fault, which are accounted for by local heating, due probably to earth movement, at some period in the history of the seam, just as there are instances of complete carbonisa- tion (coking) of part of a coal seam by volcanic intrusion. It seems impossible, however, that coals in general can ever have approached, during their formation, a tempera- ture of 300degs., and such a temperature is too low to effect complete carbonisation. The effect of pressure is adverse to molecular disinte- gration. For example, Ipatiev,§ in the course of experi- ments in thermal decomposition, observed that with increasing pressure the gases became richer in paraffins and poorer in carbon monoxide and hydrogen. There seems, in fact, no reason to believe that any of the factors, singly or combined, involved in the forma- tion of coal can have brought about the complete carboni- sation of any portion of the mother substance of coal. On the other hand, the existence in coal of substances the molecules of which are similar in type to the carbon molecule must be presumed. Dimroth and Kerkovius II have shown that the carbon molecule contains the fluorene grouping, whilst Pictet and Ramseyer U have extracted hexahydrofluorene from Montrambert coal. Moreover, both carbon and coal yield benzenehexacar- boxylic acid (mellitic acid) on oxidation, showing that in both cases there are molecules present the structure of which involves a six-carbon ring, each carbon atom being attached to another carbon atom. * Compt. Rend., 1909, 148 , 348. \Berichte, 1910 , 43, 2922. + Phil. Mag.. 1882, v. 13, 325. 5 Berichte, 1911, 44, 2978. ;| Annalen, 1913 , 399, 120. H Berio We, 1911, 44, 2486.