1130 THE COLLIERY GUARDIAN. June 15, 1917. coal always gives a black or grey black streak on paper, while the streak of lignite is always brown, even when the substance itself is black. There are, of course, other tests, such as the brown coloration given by lignite to potash solution, and the red colour imparted to a hot dilute solution of nitric acid. The bituminous coals, also, are known by the absence of lignine. These tests are often necessary, especially in prospecting work, in order to ascertain- the true nature of newly-found coal deposits; but they are not in themselves enough to determine the possible existence of transition forms from one into the other variety. Since, also, coal is a composite substance, it is not possible to draw any definite conclusion as to its constitution either from an ultimate analysis or from a consideration of its distillation products in bulk. Obviously, therefore, the first step in the investigation of the nature of the coal substance is to find some means of separating its component parts. Although but little progress has yet been made in this direction, some important advances have been made in the extraction of certain constituents by means of solvents; but, unfortunately, so far no means has been discovered whereby coal can be completely dissolved in an unaltered state. Thus, although extracts can be obtained by the action of solvents, little or nothing is yet known as to the nature of the substance dissolved. Benzol, which might be expected to act purely as a solvent, only, however, extracts a fraction of 1 per cent, of the coal substance; while basic compounds, such as pyridine, or acid substances, like phenol, although they exert a marked solvent action, cannot be assumed to act without chemical alteration of the dissolved substance. Pictet, in his experiments with benzol, believed that he could identify in the extract such substances as di - hydrotoluol, di - hydro- metaxylol, a series of aromatic hydrocarbons and certain naphthenes, similar to those occurring in petroleum. But the significance of these determina- tions is limited by the consideration that they still leave us in doubt with respect to nine hundred and ninety-nine one-thousandths of the original coal substance. Amongst other things, Pictet also discovered an optically active constituent in coal, furnishing still another point of similarity with petroleum. Drs. Fischer and Gluud subsequently succeeded in increasing the solvent action of benzol by working at a temperature of 270 degs. Cent, under pressure. By this means about 1 per cent, of the coal was dissolved, and the extract consisted of a very stable, thick oily substance, yielding, on distillation, substances like those obtained by Pictet. Coal thus acted upon was found to lose its lustre and coherence. By the action of liquefied sulphurous acid, between 0*5 and 1 per cent, of oil was obtained by Drs. Fischer and Gluud. This was found to possess the same properties as the above-described benzol extract, and the only difference in the behaviour of the two solvents was that the benzol extract contained, in addition to the oil, a brownish solid substance, insoluble in ligroin. Prof. Fischer believes that the extraction of coal by liquid sulphurous acid, which before the war cost only about one halfpenny per lb., may have some industrial application. The extraction of lignite by solvents has already been advanced technically to a definite stage in the production of the substance known as mineral wax, of which certain German brown coals yield 10 per cent. This substance is an ester of a complex fatty acid, which, according to Meyer and Brod, has a composition represented by the formula C28H5602. There is also present a complex alcohol, with at least 22 carbon atoms, and a resin of unknown composition. According to experiments by Drs. Fischer and Schneider, the yield can be considerably increased by extracting with benzol under pressure at 200 degs. Cent. Liquefied sulphurous acid likewise extracts this substance. Certain brown coals are also completely soluble in alkali, but the chemical nature of the solution has not yet been determined. A further method of investigation of the nature of coal is by distillation in vacuo, by which means Pictet obtained inter alia certain products resembling those produced by benzol extraction. These appear in the so-called vacuum tar. Amongst these con- siderable interest attaches to the naphthene series, similar to that obtained by Mabery from Canadian petroleum. Dr. Wheeler has produced somewhat similar results, with the difference that the tar contained phenols, which Pictet found to be absent. Dr. Wheeler established the fact that coals distilled below 270 degs. Cent, are not appreciably decom- posed. Between this temperature and 300 degs. Cent, the sulphur compounds begin to break down, while above 300 degs. Cent, the whole coal sub- stance begins to decompose. Pictet concludes also that at 450 degs. Cent, the distillation of tar comes to an end. Vacuum tar differs essentially from coke-oven tar in the absence of solid crystalline compounds, such as naphthalene and anthracene, but Pictet shows that the former can be converted into the latter by passing it through brightly heated tubes. This result appears to prove conclusively that coke-oven tar is a secondary product. Vacuum tar also differs from raw petroleum by its relatively high content of oxygen - bearing substances, such as phenolene. Interesting as these results undoubtedly are, it is to be noted that up to the present time no com- mercial application of coal distillation in vacuo has been found. With respect to the vacuum tar from lignites but little is known beyond the fact, estab- lished by Dr. Fischer, that this substance consists mainly of mineral wax and its decomposition products. Coming to the question of low temperature dis- tillation, Dr. Fischer recalls the almost forgotten work of Bornstein in Berlin, which seems practically to have anticipated on a small scale the more extensive experiments subsequently carried out in this direction in England and America. Dr. Fischer also describes in some detail his own experiments in low temperature distillation in a rotary still, a method which possesses considerable advantages, particularly with regard to the prevention of local over-heating. The results obtained by this process are highly interesting, and deserve the closest attention of all who are working at the problem of low temperature distillation. Another point of importance discussed in this exhaustive review is the question of nitrogen recovery. Theoretically, Dr. Fischer sees no reason why the whole of the nitrogen in coal should not be recovered as ammonia. The possibility of this result is, in fact, proved by the Kjeldahl laboratory method for the determination of nitrogen in coal and coke. The problem is closely bound up with that of the sulphur, which is present in coal partly as pyrites, partly as gypsum, and in part in organic combination. The ideal solution would be the recovery both of sulphur and ammonia as ammonium sulphate, without the employment of added sulphuric acid, in which direction there is already a practical process in working. We have seldom read so stimulating a survey of the aims and objects of coal research from the chemical aspect. A full report of Dr. Fischer’s address appears in Stahl und JEisen* and we commend it to the careful attention of our own Coal Research Committee, and of all workers in this important branch of applied science. * April 12 and April 19, 1917. INSTITUTION OF MINING ENGINEERS. The 66th general meeting of this institution was held to-day (Friday) in Burlington House, Piccadilly, London. A paper on “ The Spontaneous Firing of Coal,” by Dr. J. S. Haldane, dealt with the practical applica- tion of the research work of Mr. T. F. Winmill and by Mr. J. Ivon Graham in the Doncaster Coal Owners’ Research Laboratory. A full report of the paper and discussion will appear in our next issue. An abstract of a paper on “ Acetylene Mine Lamps,” by Mr. W. Maurice, appears on page 1123 of our present issue. “The By-Product Coking Process: Its History, Development, and Application,” formed the subject of a paper by Mr. E. Bury, which also will be dealt with in our next issue. Three other papers were open for discussion :—“ The Permeability of Coal to Air or Gas, and the Solubilities of Different Gases in Coal, by Mr. J. I. Graham; a The Absorption of Oxygen by Coal—Part X.: The Forma- tion of Water in the Oxidation of Coal,” by the same author; and “The Form and Structure of the Coal Fields of Scotland,” by Mr. D. Ferguson. South WaBes Summer Mining and Engineering School.— The summer school will be held during August at the Tech- nical College, Swansea, and courses will be provided in (1) mining engineering, (2) mechanical engineering, (3) elec- trical engineering (to include laboratory work). Full par- ticulars, prospectus, and forms of application may be obtained from the chief education official, County Hall, Cardiff, on receipt of a stamped addressed foolscap envelope. THE COM, AND IRON TRADES. Thursday, June 14. Scotland.—Western District. COAL. General conditions in the Scotch coal trade are still most unsatisfactory. It is customary at this season of the year to export a large quantity of household coal, but the restrictions on shipments and the great lack of tonnage have rendered it difficult to dispose of this class of fuel. The wagon congestion, too, is still very acute, and collieries find it almost impossible to preserve unbroken time. In the west of Scotland district industrial demands are compara- tively well maintained, but business otherwise is slow. Shipments amounted to 115,274 tons, compared with 109,941 in the preceding week and 136,740 tons in the same week last year. Prices f.o.b. Glasgow. Current L’st week’s Last year’s prices. prices. prices. Steam coal 17/6-20/ 17/6-20/6 27/6-30/ Ell 18/6-20/ 18/6-20/6 27/6-30/ Splint 21/ -26/ 21/ -26/ 32/6-42/6 Treble nuts 23/6 23/6 23/ Double do 22/ 22/ 22/ Single do 20/ 20/ 21/ BRON. Government requirements of all classes of material manufactured at the ironworks remain as insistent as ever, and employment is very full considering the available labour. New works are still being opened and additions made to existing factories and plants, and yet it appears impossible to arrest the accumulation of orders. Under the circumstances the supplies diverted to ordinary con- sumption are extremely small, and in many instances consist of mateiial otherwise rejected. In pig iron all qualities are scarce, and very few transactions are now completed on the open market, war necessities easily absorbing the output, which now practically consists of the daily production, as stocks are now at vanishing point. Prices, however, are firm and unchanged. Monkland and Carnbroe are quoted f.a.s. at Glasgow, Nos. 1, 125s., Nos. 3, 120s.; Govan, No. 1, 122s. 6d., No. 3, 120s.; Clyde, Summerlee, Calder and Langloan, Nos. 1, 130s., Nos. 3, 125s.; Gartsherrie, No. 1, 131s. 6d., No. 3, 126s. 6d.; Glengarnock, at Ardrossan, No. 1, 130s., No. 3, 125s.; Eglinton, at Ardrossan or Troon, and Dalmellington, at Ayr, Nos. 1, 126s. 6d., Nos. 3, 121s. 6d.; Shotts and Carron, at Leith, Nos. 1,130s., Nos 3, 125s. per ton. The ouput of finished iron, too, is now almost entirely devoted to war requirements, either directly or indirectly. Malleable iron makers have plenty of work on hand, but few private contracts are completed owing to the impossibility of guaranteeing deliveries. Black sheet makers have a great demand for the heavier gauges. Business in galvanised material is confined to war supplies, partly owing to the present prohibitive price. Exports all round are at a low ebb. Scotland.—Eastern District. COAL. No change has occurred in the position of the Lothians coa] trade. Almost nothing is being done in exports, and business is entirely on local and Admiralty account. Ship- ments amounted to 19,728 tons against 18,483 in the pre- ceding week and 29,880 tons in the same week last year. Prices f.o.b. Leith. Current L’st week’s Last year’s Best screened steam coal... prices. 20/ prices. 20/ prices 40/ -50/ Secondary qualities 18/ 18/ 38/ -42/ Treble nuts ..... 22/ 22/ 25/ Double do 20/ 20/ 24/ Single do 19/ 19/ 22/ The collieries in Fifeshire are perhaps feeling the pinch to a greater extent than those in any other district, owing to the fact that their usual trade is largely export and the industrial outlet comparatively small. A considerable amount of idle time is reported, and prices are inclined to become still easier. Clearances for the week amounted to 20,964 tons compared with 17,888 in the preceding week and 51,136 tons in the same week last year. Prices f.o.b. Methil or Burntisland. Current L’st week’s Last year’s Best screened navigation prices. prices. prices. coal 28/ 28/ 45/ -50/ Unscreened do 24/ 24/ 40/ -45/ First-class steam coal 23/ 23/ 40/ -50/ Third-class do 19/ 19/ 33/ -40/ 25/ -26/ Treble nuts 24/ 24/ Double do 22/ 22/ 24/ —25/ Single do. 20/ 19/ 22/ The aggregate shipments from Scottish ports during the past week amounted to 155,966 tons, compared with 146,312 in the preceding week and 217,756 tons in the corresponding week of last year. ™ ™ Nortfiumbei’IaEidj Durham aod Ciswaland. Newcastie-on-Tyne. COAL. Towards the end of last week, shipments on official account showed a marked decline, and, with few boats avail- able for charter in the open market, the outlook for the coal industry this week was not promising. The output was only being placed with difficulty, and both Northumber- land and Durham collieries suffered for want of early boats. The turn of the week witnessed a gratifyingly-large influx of tonnage—mainly, it is true, on requisitioned account and to load cargoes already arranged for elsewhere, and there was a very considerable improvement in official stemming, for steam coals especially, with the result that the Northumberland pits have been assured of steady employ- ment for the current week. Durham collieries are not so lucky, although their position is better than was fore- shadowed. Despite the latter fact, some of the pits are