580 ___________________________________________________________________________________________________________ THE COLLIERY GUARDIAN. March 23, 1917. CURRENT SCIENCE Fuel Economy on the Chicago Great Western. According to the Hailway Gazette, the Chicago Great Western, in effecting economies in fuel, has attempted, to consider every phase of the subject. The most econo- mical fuel is determined from analyses, the results obtained from actual tests, and the prices paid, all being reduced to show the cost per ton-mile. The coal from each owner is carefully sampled about twice a month, and sent to the railway company’s laboratory for analysis. Each superintendent employs a field inspector, who attends at the mine, carefully watching the prepar- ation of the coal. After the coal is received at the point of consumption a certain number of cars are examined each week, and any items of unsatisfactory preparation are taken up, with the owners and with the superinten- dent’s own inspector at the mine. Each district is required to check the weight of a certain number of trucks each week, and report the result to the general manager. The monthly performance of each fuel station is .recorded on a form, which shows in detail the results of operation, and the type of wagon in which the coal is delivered. Excessive costs for handling may be readily noted also, and indicate where investigations are necessary. Within the past five years modern coaling stations have been erected at 12 points of greatest fuel consump- tion, and by their use the cost of handling has been reduced from an average ranging between 9c. and 12c. per ton to an average ranging from 2c. to 4c. Recog- nising that fuel is one of the largest items in the cost of transportation, a .systematic programme is being followed out as to equipping engines with superheaters and brick arches to reduce fuel consumption. Mechani- cal stokers have not yet been applied, but work has been started to fix them on some of the heaviest freight engines. A form is compiled daily in the train despatcher’s office, showing the pounds of coal used on each locomotive for hauling 100 tons - one mile. Three separate sheets are used, one for passenger trains, one for through goods trains, and one for pick-up goods trains. The form also shows the percentage of the potential tonnage actually hauled. It records only the performance of individual drivers and firemen and indi- vidual engines while in service, coal consumed at ter- minals not being charged. Recovery of Benzol from Coal Gas. In the course of a paper on “ A New Method of Extracting the Vaporous Constituents from Coal Gas,” read before the Society of Chemical Industry in London, Dr. „R. Lessing said that the recovery of benzol from coal gas was a problem which had engaged the attention of the carbonising industry for the last 50 years. The process was first practised in the English ‘ ‘ carbonising works, then taken up by the by-product coke oven industry, and re-introduced into this country by Conti- nental coke oven builders. The gas industry became interested in the recovery of benzol from gas a few years ago, as a means of augmenting the supply of motor fuel, but the statutory requirements of illuminating power stood in the way of its adoption on an appreciable scale. The author then described a process he had devised for stripping gas of benzol by passing the gas through a closed vessel which ■contains porous material soaked in a suitable oil—for instance, green oil or gas oil. The inert material may consist of broken highly porous brick, or, preferably, of moulded pieces of definite .shape, volume, weight, and available surface. The vaporous compounds in the gas in which the oil is soluble, i.e., the.hydrocarbons and organic sulphur com- pounds, ■which, when isolated, are liquid at ordinary temperature, are absorbed. When the oil has taken up the required amount of the substance to be extracted, which will depend on the quantity and surface of the absorbing agent, the velocity and volume of the gas, the temperature and degree of its saturation, the mutual solubility of the vapours and the absorbing oil, and the vapour pressure of the solution formed, the gas inlet and outlet valves are closed, the gas current being directed into the second vessel of the series. Steam is then blown through the material, carrying the vapours of the absorbed compounds with it to the water-cooled condenser, and finally to a receiver fitted with overflow pipes for water and crude benzol respectively. It is advisable to provide the “ scrubber still ” with a jacket to avoid the condensation of steam, particularly on the walls. It is, however, not necessary to raise the whole of the inert carrying material to the temperature of dis- tillation. As*the oil forms a very thin film, and is therefore completely exposed to the passing steam, the volatile matter dissolved in it is distilled off before the non-conducting support is raised throughout its mass to the same temperature. When the distillation is finished the steam is shut off, and the vessel is cooled by pass- ing water through the jacket, and is then ready for the next scrubbing period. By employing three or more sets of “ scrubber stills,” they can be worked in rota- tion., a definite schedule being arranged for the three periods of scrubbing, steaming, and cooling. The labour involved is restricted to the manipulation of valves for changing over from gas to steam, and. vice versa, and to the collection of the distillate. As there are no pumps or other moving parts involved in the process, nor adjustments of the flow of oil, the plant does not require any attention except for the change-over from one period to another. The steaming is to be done only once in 24 hours, or at even longer intervals, and occupies only a fraction of the time available for scrubbing. The ground space required is, if anything, smaller than that occupied by the usual combination of scrubbing and distilling plant. Losses of oil are restricted to the portion dis- tilled off with the steam, particularly if superheated AND TECHNOLOGY. steam is used. In places where the crude benzol is fractionated, this oil can be returned in the form of residue. Elsewhere it is replaced by fresh oil, which is occasionally introduced through the top of the scrubber, and is allowed to soak into the material on its way to the bottom, where any excess is drawn off through drain cocks. Pending the elaboration and thorough testing of the process on a works scale, the author has constructed an experimental apparatus for analytical and research pur- poses based on the same principle, a diagrammatic sec- tion of the apparatus being shown in the drawing. The container A is filled with the oil-soaked inert material C, which rests on a perforated bottom B, and exerts only a negligible back-pressure to the gas. The gas to be tested enters through stop-cock D, passes downwards through the material, and through the gas outlet E, into the gas meter. The container A is surrounded by a jacket G, which is provided with a gauge H, and drain- cock J, and is filled with water during the scrubbing course as the light oils, and was collected in steel drums' at the outlet of the separator. When working on benzol they ran at a temperature of 110 to 115 degs. Cent., with just a little steam on the vapour box. Superheated steam should be used if possible. The working cost was small—about 6d. per ton of tar. Referring particularly to the working of the plant for the recovery of . benzol, Mr. Mottram said the chief thing was a good supply of water for condensing the benzol; otherwise it would escape to the gas purifier and be lost. They had a large storage tank for creosote, from which they pumped it through the washer. There was stock sufficient for two or three days, so that they were able to use the dis- tillation plant for two days on tar and one on benzol, and so adapt it for both purposes. Before they started washing with creosote they were free from naphthalene, but, unfortunately, the creosote contained a high per- centage. They were spraying naphtha into the gas to counteract the naphthalene, but this should not be necessary if the cause of the trouble was removed. ________________ MINING EMPLOYMENT STATISTICS. The Board of Trade Labour Gazette states that H w s s ‘«i:| III M s iBli employment in coal mining was good during February, but showed a marked decline as compared with either a month ago or a year ago. In several districts short time was worked, largely owing to difficulties of trans- port. There was an increase of 2,004 (or 0 4 per cent.) in the number of workpeople employed compared with the previous month, and of 28,698 (or 5’5 per cent.) compared with a year ago. Of the 548,437 workpeople included in the returns for February 1917, 252,353 (or 46 per cent.) were employed at pits working 12 days during the fortnight to which the returns relate, while a further 153,421 (or 28 per cent.) were employed at pits working 11 but less than 12 days. Districts. W ork- people em- ployed in Feb. 4917* Average No. of days worked per week by the collieries in fort- night ended Feb. Jan. Feb. 24, 27, 26, 1917. 1917. 1916. Inc. (■♦-) or dec. (—) in Feb. 1917, on a Month Year ago. ago. England $ Wales. Days. Days. Days. Days. Days. Northumberland ... 35,514...4’36... 4’91... 5’50... —0’55... —1’14 Durham .......... 85,853...4 92...5’36...5’60...-0’44...-0’68 Cumberland ...... 7,417...5’91...5’81...5’73...+0’10 ..+0’18 South Yorkshire ... 66,765...5’85... 5 92...5’87... - 0’07... - 0’02 West Yorkshire.... 25,578...5’85...5’80...5’71 ..+0’05... f0’14 Lancs. & Cheshire... 51,250...5’79...5’93...5’83...-0T4...-0’04 Derbyshire .................. 33,884...5’75...5’78...5’77...-0’03...—0’02 Notts and Leicester 30,143...5’66...5’66...5’45... — . + 0’21 Staffordshire ...... 27,534...5’72...5’85...5’60...-0’13...+0’12 W arwick, W orcester and Salop........ 8,524...5’68...5’81...5’70...-0’13...-0’02 Gk/ster & Somerset 6,272...5 93...5’91...5’83... +0’02... +0’10 North Wales .’..... 9,844.. 5’96...5’94...5’88 +0’02 +0’08 South Wales & Mon. 110,550...5’58 . 5’74...5’87...-0’16...-0’29 period. The gas is passed through the apparatus at the rate of about 5 cu. ft. per hour, and about 100 cu. ft. are used for one experiment. This will, therefore, cover a period of 20 hours, during which the apparatus does not require any attention at all. Stop-cocks E and D are then closed, K is opened, and the water run out through drain-cock J, until it fills only about one-third of the jacket. A gas ring burner R is then lit, and steam is raised in the jacket, the excess steam escaping through the condenser 0. When the water is well boil- ing, K is shut, and stop-cocks M and N are opened, the pressure having been relieved from time to time through N. At the same time, the Bunsen burner S is lit. The steam raised in the jacket passes now through the super- heater coil L, and stop-cock M, to the bottom of the inner container, and up through the absorbent material. The steam and vapour pass through N and condenser 0, and are collected in a graduated separating funnel clamped to the stand under 0. P is the inlet for the cooling water, and Q its overflow. The charging hole T, through which the material is put into the apparatus, is closed by a screw-cap. Any water condensing in the vessel or surplus oil is drawn off through drain-cock F. The steam distillation, including heating up, takes from 1 to hours, and is usually carried on until the absorbed naphthalene is distilled over. To avoid block- ages in the condenser, it is advisable to allow the cooling water to get hot before the naphthalene stage is reached. By drawing off the hot water and running cold water through the jacket, the apparatus cools rapidly, and is then ready for scrubbing again; so that the complete cycle of operations can be carried out within 24 hours, and therefore daily tests can be made. According to the vapour contents of the gas being tested, from 100 to 200 c.c. of steam distillate is obtained. This is separated from the water, measured, and further examined by distillation. Dehydrating and Debenzolising Tar. At the annual meeting of the Manchester district of the Institution of Gas Engineers (Gas World), Mr. A. E. Mottram, describing the tar and benzol plant at the Ossett Gas Works, stated that they had put in a Wilton tar dehydrating plant of a capacity of 100 gals, per hour, which was very simple to work. The temperature could be regulated by the forced-draught Wilton breeze fur- nace, or by the speed of the Evans pump, which feeds the still through the economiser. When making tar for the Road Board specification No. 1, they worked at 160 to 180?degs. Cent.; and for specification No. 2 at 220 to 240 degs. Cent. The back pressure in both cases was about 301b. When working on benzol, the creosote oil followed the same course as the tar, and was then passed through a water-cooled condenser into the creosote storage tank, to be used over again. The benzol followed the same Total ...... 499,128...5 49...5’67...5’73...-0T8...-0’24 Scotland. West Scotland ____ 20,299...5’40...5 49...5 37.,. — 0’09... + 0’03 The Lothians ...... 2,624...5’47...5’58...5’44...-0T1...+0’03 Fife ............... 25,945...4’91...5’48...5’50...-0’57...-0’59 Total ...... 48,868...5’14.. 5’49...5’44...-0’35...-0’30 Ireland ........... 441...5’66 5’61...5’21...+0’05.. +0'45 _______ Total, U.K_____ 548,437.. 5’46...5’66...5’71...-0’20...-0’25 * 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 the pits at which the workpeople were engaged:— Description of coal. Anthracite ...... Coking .......... Gas.................... House........... Steam........... Mixed........... Average No. of days worked per Work- week by the pits people in fortnight em- ended Inc. (+) or dec. ( —) in Feb. 1917 on a ________________ ployed ,-----------------> t------A— in Feb. Feb. Jan. Feb. 1917 * 24, 27, 26, Month Year 1917. 1917. 1916. ag0’ ag0’ Days. Days. Days. Days. Days. 6,057 . 4’81...4’76.. 5’29... + 0’05...-0’48 27,432...5’71...5 74...5 77...-0 03...-0’06 32.619.. .4’73..5’45...5’57...-0’72...-0’84 54.188.. .5’51...5’64...5 55...-0’13...-0’04 194,260...5’50...5 66...5’80... -0’16...-0’30 233,881. ..5’51. ..5’70. ..5’69...-0’19. ..-0’18 All descriptions ... 548,437...5’46...5’66...5’71... — 0’20 .. -0’25 * At the collieries included in the table. Iron mining.—At iron mines employment continued very good and was better than a year ago. Returns received for each of the three periods named below, relating to the same mines and open works in each case, show that 14,036 were employed in February 1917, an increase of 47 (or 0’3 per cent.) compared with January, and of 734 (or 5’5 per cent.) compared with a year ago. Districts. Average No. of days worked per Work- week by mines people in fortnight em- ended ployed (---------A-------\ in Feb. Feb. Jan. Feb. 1917. 24, 27, 26, 1917. 1917. 1916. Inc. (+) or dec. (—) in Feb. 1917 on a __________ Month Year ago. ago. Days. Days. Days. Days. Days. Cleveland........... 5,977 ...5'87...5’83...5’79...+0 04... + 0’08 Cumberland and Lancashire ...... 4,646 ...5’89 . 5 94...5’94... —0’05... —0’05 Scotland ........... 797 ...5’93...6’00...5’84...-0’07...+ 0’09 Other districts .... 2,616 ...5’88.. 5’94...5’73... —0’06... + 0’15 All districts... 14,036 ...5’88...5’90.. 5’83...-0’02...+0’05 The weekly average number of days worked by the mines and open works included in the returns was 5’88, compared with 5’90 a month ago and 5’83 a year ago. Shale.—The returns received show that 2,669 work- people were employed in the fortnight ended Feb-