THE COLLIERY GUARDIAN. 817 October 18, 1918. ____________________________________________________________________________________________________________________________________ _____________________________ ____________________________________________________________________________ CURRENT SCIENCE Grab Cranes for Coaling Locomotives. According to the Organ fur die Fortschritte des Eisenbahnw esens, grab cranes possess the advantage that the coal or coke can be lifted from any part of the heap, and so prevent spontaneous combustion spreading. During the war coal and coke have been made into stacks 7 metres high without hesitation. Another advantage is that the locomotives can be cooled and supplied with water and sand while the ashes and clinker are being cleared out and the smoke box cleaned. The grab is specially suitable for small coal and such as is of soft quality, as large lumps of hard coal cannot be dealt with so readily. Two kinds of grab are shown, one with a double scoop, and the other with a quadruple scoop. At Fintrop the distance between the track for coaling and that for the coal wagons is 5 metres, and this space is used for dumping ashes and clinker. It is paved with fire- proof stone, and provided with cooling jets. Retorting Lignite Under Pressure: A U.S.A. Research. In a paper presented to the South Western Elec- trical and Gas Association (abstracted in Gas World), Prof. E. P. Schoch, of the University of Texas, deals with the possibilities of lignite as a gas-making material. Simple trials made to retort lignite in the ordinary way in which bituminous coal is retorted have revealed that the gas obtained is of low calorific value (about 350 B.Th.U. per cu. ft.), that the oily distillate obtained is composed of the high boiling members of the paraffin series, that the tar is a rela- tively poor binder, and its amount is only great enough to bind the solid residue when the distilla- tion is continued until the residue is absolutely dry coke. The ordinary retorting of coal employs none of the well-established principles of modern chemical syn- thesis, and is altogether a hit-and-miss proposition. The coal is placed in the retort in relatively thick layers, which is heated up gradually from layer to layer. In general, the products of distillation formed by the outermost or first-heated layers pass through layers which are at temperatures somewhat lower than those in which the products are formed, and hence the products formed at low temperatures pass through layers which are so cool that no further reaction takes place between the gases and the solids through which they pass, while the products formed at high temperatures pass through layers of hot solids, with which they undergo extensive further reaction. With the retorting of good bituminous coal, nothing but desirable products are obtained under these “ automatically ” controlled conditions, but with the same automatic control lignite yields mainly undesirable products. Consideration of the factors affecting the formation of hydrocarbons in the retorting of coal or lignite reveals that pressure is one of the first factors to be considered and controlled. It is a well-known prin- ciple that a greater pressure will favour the forma- tion of compounds richer in carbon, because the number of molecules is smaller than it would be if the compounds were richer in hydrogen. Thus, in the extreme instance of the gas obtained by retorting lignite under atmospheric pressure, the gas contains much free hydrogen with relatively little methane, while the gas obtained under higher pressures con- tains less hydrogen and more methane. This explains why the retorting of lignite under about seven atmo- spheres pressure, 105 lb., gives a gas with a calorific value of 740 B.Th.U., while under one atmospheric pressure the gas obtained has a calorific value of only 350 B.Th.U. Another factor is the relation between the time re- quired for the reaction and the rate at which each portion of coal is heated in the retort. If the coal is heated slowly, then it will undergo one reaction at the low temperature, another reaction at the next higher temperature, etc. ; but if the coal is heated very rapidly throughout—to any desired high tempera- ture—it will undergo reaction or reactions of a different character, because the coal contains many substances capable of reacting which with slow heat- ing will have been removed before the desired high temperatures are reached. A third factor is the passage of gaseous products through hot layers of coal of different composition from the layers in which they were formed. This factor serves to change the amount and nature of the products obtained during the time that any particular mass of coal is at a high temperature. It is now recog- nised that this action ought to be brought into play much more extensively; for instance, by a long con- tinued dropping back of condensed products upon the hot mass. The systematic application of one or another of these influences should certainly enable us to change lignite deliberately by retorting it into desired products, just as the “ automatic ” application of these influences brings about the desirable changes in the retorting of coal; but the difficulty in the way at present is our lack of definite knowledge concerning the effects of these various factors. Hence the first step in the solution of this problem consists in the determination of the effects due to these separate influences. The University of Texas is engaged on a research in the matter. An autoclave of 1 cu. ft. capacity, capable of withstanding 1,000 lb. pressure, is used and is supplied with a pressure gauge, a safety valve, and an effluent tube connecting with a tar trap, a condenser for the oils, and a pressure reduction valve to allow the gas to escape “ non-explosively ” into a gasholder. There is also a tube connection for in- jecting hydrogen under any desired pressure. The powdered lignite is placed inside a cylindrical vessel, the internal open space of which is 4 in. in diameter and 16 in. long. This vessel is suspended with its upper edge 1 in. below the lid of the auto- AND TECHNOLOGY. clave and fastened to the lid. There is an open space of 1 in. width all around between this vessel and the autoclave, and a free space of 2 in. between them at the bottom. This centra] vessel is essentially a tube of burnt fireclay with a spiral groove, on the inside of the wall, extending from the top to the bottom—two turns to the linear inch of length. A No. 9 iron wire in this groove serves as the heating- element. A current of 8 to 12 kw. heats the lignite up to any desired temperature in a few minutes. The lignite is stirred by means of a rectangle 2 in. by 16 in., made of | in. iron rodding, one of the 16 in. sides having extensions which serve as the axis of the stirrer, and the other 16 in. side passes around close to the walls of the vessel, and thus brings all portions of the lignite rapidly into direct contact with the source of heat. For temperature observations pyrometer couples are inserted into the linings at the top and bottom of the vessel. To make an experiment, the vessel is filled with approximately 8 lb. of dry powdered lignite. After filling the central vessel and closing the autoclave gastight, it is filled with hydrogen gas to any desired pressure (ranging from 100 to 800 lb.), then the stirrer is started, and finally the heating current (direct current, 50 to 100 volts, 50 to 100 amperes) is turned on, the aim being to heat the lignite as rapidly as possible (five minutes) to any desired temperature (300 degs. to 1,000 degs. Cent.) with the smallest current that will accomplish the result. A great deal of the oil and tar is condensed on the cold walls of the autoclave, and the rest in the condenser and tar trap. The gas is allowed to escape (into a gasholder) at such a rate as is necessary to maintain the pressure in the autoclave constant. When no more gaseous products are formed, the current is turned off, the gas is allowed to discharge into the gasholder until the pressure has dropped to one atmosphere, and the remainder of the gaseous hydrocarbons is blown out of the autoclave with some more hydrogen (sometimes with carbon dioxide). The gas, oil and tar are analysed. Then another trial at a different tempera- ture (or pressure) is made, and it is intended to con- tinue until a curve of effects of temperature extending from 300 to 1,000 degs. Cent, and of pressures from 100 to 800 lb. is obtained. Average No. of days worked per week by mines in fortnight ended ________A_______ Inc. (+) or dec. (—) in Sept. 1918 on a of 201 (or 1-0 per cent.) on the previous month, and of 230 (or 1-2 per cent.) on a year ago. Work- people Districts. em- ____________ ployed r- y r -----------x X A24g’ Se22t' Month Year ivlo. £19 1918. 1918. 193 7. ag0, ag0’ Days. Days. Days. Days. Days. Cleveland.......... 7,463 ...6’00...6’00...5'96... — +0’04 Cumberland and Lancashire ...... 6,499 ...5 88...5’98...6’00... — OTO ..— 0T2 Scotland .......... 603 ...6’00...6'00 5'80... —...+0'20 Other districts .... 4,889 ...5'83 . 5 95...5’84...-0T2...-0’01 Total ..... 19,454 ...5’91...5’98 . 5'94...-0'07...-0'03 * At mines included in the returns. Shale.—The returns show that 4,920 workpeople were employed in the fortnight ended September 21, 1918, compared with 5,054 workpeople in August and with 5,055 in September 1917, at mines which worked six days in each /period. Pig Iron Industry.—Employment continued good during September. Districts. No. of furnaces, included in the returns, in blast at end of A Inc. ( + ) or dec. (-) in Sept. 1918 on a Sept. Aug. Sept. Month Year England ft Wales: 1918. 1918. 1917. ago. ago. Cleveland 73 . .. 73 ... 76 . — —3 Cumberland & Lancs. 33 . .. 33 ... 34 . .. — ... -1 S. and S. W. Yorks ... 12 . .. 12 ... 13 . .. — ... —1 Derby & Nottingham... Leicester, Lincoln and 33 . .. 35 ... 33 . —2... Northampton 29 . .. 29 ... 29 . — Staffs and Worcester... 30 . .. 30 ... 31 . .. — —i S. Wales & Monmouth 11 . .. 12 ... 12 . .. -i... -i Other districts 4 . .. 4 ... 5 . .. — ... -i —— 225 . .. 228 . . 233 ... -3... —8 Scotland 67 . .. 67 ... 61 . ... — ... +6 —■ — ■ Total, U.K 292 . .. 295 ... 294 . .. —3... —2 ________________ MINING EMPLOYMENT STATISTICS. The Board of Trade Labour Gazette for September reports that employment in coal mining continued good during September. There was an increase of 4,045 (or 0-8 per cent.) in the number of workpeople employed at the collieries making returns, as com- pared with the previous month, and a decrease of 27,940 (or 4-9 per cent.) on a year ago. Of the 538,789 workpeople included in the returns for Sep- tember, 296,540 (or 55 per cent.) were employed at pits working twelve days during the fortnight to which the returns relate; a further 210,726 (or 39T per cent.) were employed at pits working eleven but less than twelve days. Districts. Work- people em- ployed in Sept. 1918.* Average No. of days worked per week by the collieries in fort- night ended Inc. (4-) or dec. (—) in Sept. 1918 on a England Wales. Northumberland ... Durham ........ Cumberland .... South Yorkshire ... West Yorkshire... Lancs. & Cheshire... Derbyshire ...... Notts and Leicester Staffordshire .... W ar wick, W orcester and Salop...... Glo'ster & Somerset North Wales .... South Wales & Mon. ________ S9ipt’ S92t' Month Year 1918. 1918. 1917. ag0- ag0' Days. Days. Days. Days. Days. 36.690.. .5’47...5’48...5'22...—0’01... + 0'25 88.777.. .5'44...5'56...5'06...—0T2... + 0'38 6,184...5’86...5’77...5’81... 4-0'09... +0'05 57.950.. .5'90...5'18...5'87... +0'72... +0'03 24,069...5'88...5'40...5'82 .. +0'48 +0'06 49.516.. .5’88...5’85...5’84...+0’03...+0’04 34,359. ..5'85. ..5'86... 5'84...-0'01... +0 01 32.228.. .5'76...5'64...5'65... +0'12... +0 11 28,008...5'62...5'75...5'71,..-0T3...-009 8.393.. .5'91...5’79...5’66... +0’12... 4-0'25 5.505.. .5’91...5’97...5’88...—0’06... + 0'03 9.903.. 5'96...5'90...5’91 +0’06...+0'05 111,217...5’93 . 5'98...5’36...-0’05... +0’57 Total ....... 492,799...5 76.. 5’68...5’53... +0’08... +0’23 Scotland. West Scotland ____ 20,732 5’31...5 38...5’26...-0’07... + 0’05 The Lothians __........... 2,120 5'43...5’56...5’71... - 0’13...-0’28 Fife ................ 22,617 . 5'61...5’68...5’20...-0’02... +0'41 Total ....... 44,469.. 5’46...5’51 5’25...-0’05... + 0’21 Ireland ........... 521...5’39...5’14...5’51... +0’25... -0'12 Total, U.K...... 538,789... 5’74... 5’67... 5’51... +0’07... + 0’23 * At the collieries included in the table. The following table shows the numbers employed and the average number of days worked, distributed according to the principal kind of coal raised at pits kpeople were engaged : — Average No. ©f days worked per Inc. (+) or Work- week by the pits dec. ( — jin people in fortnight Sept. 1918 em- ended @n a ployed (-------A-------(--------*----' in Sept. Sept. Aug. Sept. 1918 * 21, 24, 22, iVlontn Year at which the wor Description of coal. ZjL» 1918. 1918. 1917. ag0- ago’ Days. Days. Days. Days. Days. Anthracite ......... 4,807...5’82...5’84...5’00...-0'02... +0’82 Coking ............. 25,368...5’64...5’72...5 68...-0T1...-0’07 Gas.................. 36,498...5’40...5'49...4’82...-0’09... +0’58 House................ 51,603...5’66...5’69...5’58...-0 03...+0’08 Steam................ 188,969...5'82...5’14...5 55... +0’08... +0’27 Mixed................ 231,544...5'75...5’62...5’56...+0’13...+0'19 ______ ______ ______ All descriptions ... 538,789...5’74...5’67 5’51...+0’07 . +0’23 * At the collieries included in the table. Iron Mining.—Returns received relating to the same mines and open works show that 19,454 work- people were employed in September 1918, an increase Iron and Steel Works.—Employment continued very good at iron and steel works. According to returns relating to 116,983 workpeople, the number of shifts worked during the week ended Septembr 21, 1918, was 668,851, showing an increase of 4,042 (or 0-6 per cent.) on the previous month, and of 2,935 (or 0-4 per cent.) on a year ago. Engineering Trades.—These trades continued to be extremely busy during September, and a great amount of overtime was worked. Trade unions with 331,703 members (mostly in skilled occupations) reported 0T per cent, unemployed at the end of September, com- pared with 0T per cent, a month ago and 0-1 per cent, a year ago. Tinplate.—The number of tinplate mills working at the. end of September showed a decrease of two compared with August, and an increase of 30 on a year ago. Mills making steel and galvanised sheets showed an increase of one on a month ago, and an increase of five on a year ago. Tubes.—Employment was very good on Government work at Birmingham, and was good in Wednesbury and South Wales. Disputes.—In mining and quarrying 14 new dis- putes (affecting 10,384 workpeople) occurred in Sep- tember. Near Durham a dispute concerning the wages of putters extended over 14 days and affected 5,000 workers. Work was resumed pending negotia- tions. At Liverpool the coal heavers (2,000) opposed the award regarding their demand for an additional war wage, but after five days they resumed work unconditionally. Later there was further dissatis- faction, but the men accepted the award. Wages.—In the period January-September the net increase of wages in coal mining amounted to £410,200 weekly, and it affected 900,000 workpeople. The principal changes in September were in Durham, Derbyshire, Notts, Bristol district and Radstock. The rates of pay of the different classes of workers affected were increased. Prices and Wages in the Coal and Iron Trades. The results of recent ascertainments of the selling prices of coal and iron are given below :— Prices according to Inc. (+) or dec. (—) last audit. of last audit on ________________ _________ ______ Product and Period Average district. covered bv sellin£ Previous A year last audit p^n audlt ag0’ Coal. 1918. s. d. s. d. s. d. Average of all classes of coal at pit’s mouth.) Northumberland... June-Aug.... 22 2f... + 3 11...+ 6 51 Pig Iron. Cleveland ....... July-Sept. .. 118 lOf* +11 01...+*23 If (No. 3 Pig Iron) Manufactured Iron. North of England July-Aug.t 291 10t...+ 9 Ilf + 18 51 (Bars and angles.) Midlands......... July-Aug. . 321 1|...+ 5 111...+ 15 3f (Bars, angles, tees, sheets, plates, hoops, strips, etc.) West of Scotland July-Aug. . 301 If... <- 7 10f...+ 14 81 (Rounds, squares, flats, tees, angles, hoops and rods.) * Including Government subsidies. The average price exclusive of the subsidy was 105s. 2d. per ton. f The ascertained selling price of manufactured iron in the North of England for the quarter ended June was 282s. 8'62d. per ton. Coal.—No change in the wages of Northumberland miners was made in connection with the ascertain- ment of the average selling price of Northumberland coal for the above period. Fatalities.—Mine fatalities totalled 103 (93 under- ground and 12 surface), an increase of 18 compared with the previous month, and a decline of 8 compared with a year ago.