1150 THE COLLIERY GUARDIAN June 7, 1918. Of these, perhaps the most likely to be profitable is a better knowledge of the theory and practice of combustion, and the instructions given in this paper should be carefully studied. The Coal Controller would do well to issue some such directions for the use of householders in this country. The conditions are not altogether similar to those in America, but the principles are the same, and the causes of waste are identical. AIR RECEIVER EXPLOSIONS. By L. Balliet. The explosion of receivers in compressed air lines and the conduits for compressed air is frequently ascribed to the failure of the safety valve; but whilst the safety valve is an excellent thing to have upon an air receiver, in case of over-pressure and particu- larly for the moral effect that it has upon the workmen, the provision of a hundred safety valves would not prevent explosion. Air receiver explosions are seldom, if ever, caused by excessive pneumatic pressure, but, on the other hand, are really the explo- sions of highly combustible oil gases and vapours pumped into the receiver from the compressor. It is almost impossible to supply lubrication to a com- pressor in sufficiently small amounts to preclude some oil gases being carried into the receiver and conduits. Air compressing is the reverse operation of the steam engine. With steam, the pressure is built up in an enclosed boiler, conducted into the cylinders of an engine where it expands, giving off power or energy, and is then exhausted into the atmosphere. The lubricators of a steam engine can safely use almost any amount of oil because it is exhausted into the open air. The air compressor receives its air at atmospheric pressure; power is applied to the pistons for the purpose of compressing it, to be exhausted into an enclosed receiver. Every bit of lubrication fed into the cylinders of an air compressor must eventually pass into the receiver. It is well to call attention to the fact that the cylinders of an air compressor are not subject to the scouring action that the steam cylinders of an engine are, hence it needs less lubrication in the first place. Frequently engineers adjust the lubricators for the steam end and the air end of the compressor alike, and sometimes when automatic governors control the speed of the compressor the lubricators feed the same amount of oil per minute at slow speed that they feed at high speed. There is, or should be, always an attempt to use lubricating oils that are low in carbon, but no matter what method of lubrication is used it may always be put down as a fact that more or less oil gas and oil vapour from lubricating oils is pumped into the air receiver. This is combined with more or less dust gathered from the air, some of which settles in a thick viscous scum upon the inside of the receiver shell, while some of it passes off in gas through the conduits and tools. In fact, men in poorly ventilated mines have been known to be overcome from oil gases that come from the exhaust of rock drills. The passing of a carbon spark, that may have be- come ignited with the heat of compression or friction, into the air receiver might, and probably does, cause the ignition of the oil gas within the receiver, which results in a violent explosion. Another point is that all lubricating oils used in compressors are marked with a supposed flashing test to indicate the temperature at which the oil will flash, but these tests have all been made at atmospheric pressure, a condition which does not exist in the inside of an air receiver; nor does the test indicate at what temperature the flash will occur when the lubricating oil has been broken down into a gas. In the same way that a candle taken down into a caisson, where the operations are conducted under two or three atmospheres, will burn with a much more brilliant flame than the same candle will burn at atmospheric pressure, the combustion of lubricating oil and oil gas must be more violent and rapid under a pressure of eight or more atmospheres than at atmo- spheric pressure, and it would seem that the so-called flash point of liquid lubricating oil at atmospheric pressure is of little value because it does not give the point at which the oil gas will flash under pressure. It follows from the foregoing that the air receiver should be supplied with a manhead, and that it should be opened and thoroughly cleaned of the oil and dust that accumulate on the inside of the shell; that it should be frequently drained, and the lubrication of of the compressor reduced to the minimum, and that only the best grades of oil should always be used in the compressor cylinder.—Power Plant Engineering. Shorter Working Day in Canada.—The Government of British Columbia has introduced a Bill providing that the eight-hour day for all surface workers at mines shall be reckoned from bank to bank. The coal mine operators of British Columbia are not in favour of the contemplated legislation. They have lodged their protest with the Minister of Mines. In discussing the matter with the Minister, they suggested that the proposed law might be deferred to six months or a year after the end of the war. Escape Holes for Coal Trimmers.—The Marine Depart- ment of the Board of Trade has issued a circular (No. 1589) being instructions to surveyors respecting escape holes for coal trimmers. It has been represented to the Board that, in the case of certain vessels loading coal cargoes, the means of exit from the holds are not sufficient to safeguard the lives of those engaged in trim- ming and stowing the cargo. The vessels mostly con- cerned are two-decked vessels, mainly foreign, not originally intended for the coal trade, but brought into that trade. . The Board regard it as essential that, in all vessels loading coal barges, sufficient means of exit should be provided to meet emergencies which may arise at the time of loading. The. circular then sets out instructions which are to be complied with in all new vessels intended for carrying coal cargoes, and which should also be com- plied with in existing vessels so far as is practicable. THE COAL AND IRON TRADES. Thursday, June 6. Scotland.—Western District. COAL. Conditions ruling in the Scotch coal trade show no alteration. The demand for fuel from all sources is unabated, and considerable inconvenience is being caused by the restricted output. The requests for shipping supplies improved of late, and with industrial and house- hold requirements maintained at a high level, consumers are not always able to secure adequate deliveries. Ship- ments for the past week amounted to 93,278 tons, against 82,922 in the preceding week, and 109,941 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 27/6 | 27/6 17/6-20 6 Ell 26/6-28/ 26/6-28/ 28/ -30/ 18 6-20/6 Splint 28/ -30/ 21/ -26/ Treble nuts 23/ 23/ 23/6 Double do 22/ 22/ 22/ Single do 21/ 21/ 20/ IRON. There is no diminution in the pressure for all classes of Scotch iron, and makers have great difficulty in keeping down arrears of deliveries. While the output of pig iron continues to increase, requirements seem to grow with greater rapidity. The production of haematite still absorbs the greater attention, and the output of foundry and forge qualities is growing scarcer. Shipping licences are now seldom granted but, notwithstanding, export values are firmly maintained. Aproximate prices are still round about the following figuresMonkland and Carnbroe f.a.s. at Glasgow, Nos. 1, 140s., Nos. 3, 135s.; Govan, No. 1, 135s., No. 3, 130s.; Clyde, Summerlee, Calder and Langloan, Nos. 1, 150s., Nos. 3, 145s.; Glengarnock at Ardrossan, No. 1, 140s., No. 3, 135s.; Eglinton at Ardrossan or Troon and Dal- mellington at Ayr, Nos. 1, 145s., Nos. 3, 135s.; Shotts at Leith, No. 1, 150s., No. 3, 145s. per ton. Malleable iron makers still experience a strong demand for their products, especially in the small sizes. Their steel departments, too, are continually active and the bulk of the orders passing through are on Government account. Makers of cast iron pipes have a considerable amount of national work in hand. Exports generally are dull. Scotland.—Eastern District. COAL. Business at the Lothian collieries is brisk, and outputs are quickly taken up. Local demands are good, and the shipping turn-over is fair, while the Admiralty orders are of considerable dimensions. Clearances for the week amounted to 18,201 tons, against 16,620 in the preceding week, and 18,483 tons in the same week last year. Prices f.o.b Leith. Current L’st week’s Last year’s prices. prices. prices Best screened steam coal... 26/6 26/6 20/ Secondary qualities 25/6 25/6 18/ Treble nuts 23/ 23 22/ Double do 22/ 22/ 20/ Single do 21/ 21/ 19/ A strong demand exists for all classes of Fifeshire fuel. Local requirements are prominent, while shipping orders are not neglected, and high prices are ruling for consign- ments to neutrals. Shipments were 42,645 tons, against 39,270 in the preceding week, and 17,894 tons in the same week last year. Prices f.o.b. Methil or Burntisland. Best screened navigation coal Current prices. 29/ -31/ 24/ -25/ 28/ 24/ 23/ 22/ 2!/ L’st week’s prices. 29/ -31/ 24/ -25/ 28/ 24/ 23/ 22/ 21/ Last year’s prices. 28/ 24/ 23/ 19/ 24/ 22/ 19/ Unscreened do First-class steam coal Third-class do Treble nuts Double do. Single do The priced quoted only apply to French and Italian business; for all other orders 2s. 6d. or more per ton must be added, with the exception of second-class Lothian large coal. The aggregate shipments from Scottish ports during the past week amounted to 154,124 tons compared with 138,812 in the preceding week, and 132,384 tons in the corresponding week of last year. Northumberland, Durham and Cleveland. N ewcastle-on-Ty ne. COAL. Never in the history of the local mining industry since the fateful days of August 1914 have collieries been busier. At the present time they are finding it impossible to deal expeditiously with the whole of the transport facilities which await loading. Requisitioned steamers and railway wagons there are galore, and although the pits are working at their utmost capacity of output and the miners are, generally speaking, putting in full time and “slacking” is practically unknown, there is undoubtedly a tendency towards accumulation, both of steamers and of trucks. This is due partly to the almost unprecedented demand on official account, partly to the great strength of enquiry caused by home needs, partly to some diversion of official business in recent days from South Wales, where labour troubles have impeded output, and partly to the fact that the “ comb-out ” of miners has largely denuded the pits of the younger men, whose function it was to get the coals away from the working districts of the collieries to bank. It has been promised that a considerable number of men of low medical category will be released from the Army to assist in coal production; but it is certain that these men cannot adequately replace the healthy and vigorous youths who have been taken, although, of course, they will lessen the difficulties. Much neutral business has been, and still is, on offer; but, excepting in rare cases where comparatively small quantities of fuel have been thrown on the market by some accident, these foreign customers have had to go unsatisfied. At the time of writing, “coalmen ” are unable to entertain orders for neutral destinations for loading before August, and the recent advances in prices are fully main- tained in all instances in which they have not actually been capped. The following increases are shown on the week:— Best steams, Blyths, quoted at 65s. per ton, an increase of 5s.; steam seconds, Bly ths or Tynes, 55s., an advance of 10s.; smithies, 40s., a rise of 6s. 6d ; gas bests, 45s., an increase of 5s.; coking coals, 40s., an increment of 5s , and house- holds, 60s., a similar advance. Tenders to supply the Swedish State Railways with 35,000 tons of steam coals for delivery over July, August and September are being sub- mitted on the basis of 60s per ton, plus 5 per cent, for best Blyths and 35s. per ton for smalls. Nowadays, export licences for large coals are only being granted on condition that the cargoes contain 25 per cent, of smalls—this device being resorted to in order to check the accumulation of the latter, and, indeed, merchants are being urged to recom- mend the shipment of unscreened steams wherever possible. This recommendation is being fairly cheerfully accepted by neutral customers, who recognise that they have not much option if shippers on this side care to insist, and the result is that, in some instances, entire cargoes of smalls, are being taken. There are, of course, many cases in which, whilst the use of large coal is preferable, it is quite practicable to utilise the smaller and dirtier fuel. Prices f.o.b. for prompt shipment. Steam coals :— Current prices. L’stweek’s prices. Last year’s prices. Best, Blyths (D.C.B.) ... 30/ -65/ 30/ -60/ 30/ Do. Tynes (Bowers,&c.) 29/6-60/ 29/6-60/ 28/ -30/ Secondary, Blyths ...... 25/6-55/ 25/6-45/ 21/ -22/ Do. Tynes (Hastings or West Hartleys) ... 27/ -55/ 27/ -45/ 22/6-23/ Unscreened 23/6-40/ 23/6-40/ 20/ -40/ 18/6-35/ 18/ -20/ Small, Blyths 20/ -40/ 18/ Do. Tynes 18/6-35/ 16/ -17/ Do. specials 20/6-40/ 20/6-40/ 17/6-18/ Other sorts:— Smithies 25/ -40/ 25/6-33/6 21/ Best gas coals (New Pelton or Holmside) 25/ -45/ 25/ -40/ 25/ -26/ Secondary gas coals (Pelaw Main or similar) 23/6-35/ 23/6-35/ 17/6-19/ Special gas coals 26/6-45/ 26/6-45/ 29/ -30/ Unscreened bunkers, Durhams 26/6-40/ 26/6-40/ 16/6-19/ Do. do. N orthumbrians 26/6-40/ 26/6-40/ 18/ -20/ Coking coals 24/ -40/ 24/ -40/ 24/ -35/ 18/ -20/ Do. smalls 24/ -35/ 1 16/ -18/ House coals 28,6-60/ 28/6-55/ ! 27/6-30/ Coke, foundry 42/6-50/ 42/6-50/ ) 40/ -42 6 Do. blast-furnace 42/6-50/ I 42/6-50/ ! 35/ -40/ i 40/ Do. gas ’. 35/ -40/ | 30/ -32/ Sunderland. COAL. The coal market is strong in all respects, and the outlook for forward positions is very bright. All classes are in keen request, and the output is much below requirements, chiefly owing to the heavy demands for Admiralty purposes and on inland account. Steam, gas and manufacturing qualities are already fully booked for weeks ahead, and very little coal is available for neutrals, who, nevertheless, con- tinue to enquire for it. Prices for neutrals are strongly held at recent maximum figures, and for the better qualities the tendency is upward. Wear special gas coals are 42s. 6d. per ton, and bunkers command from 32s. 6d for ordinary brands up to 40s. for best. Coke is equally scarce and firm, with little obtainable for shipment—50s. per ton being generally quoted for beehive and patent coking qualities. M iddlesbrough-on-Tees. COAL. All kinds of coal are in heavy demand, but quests for prompt replies are vain. Any small lots to spare command high figures. Official absorption remains heavy both for shipment and rail, and enquiry on behalf of neutrals is very substantial. For Allied and home sales official quota- tions prevail, but for outside business gas coal is as high as 45s., and as much as 40s. is named for bunkers. The coke situation is not so satisfactory as it has been. There is no increase in the supply, and the quantities are insufficient to fully meet needs. Apprehension is expressed regarding the near future. For home use foundry quality is 38s.; average blastfurnace kind 33s. at the ovens ; and low phosphorus sort 35s. 6d. at the ovens ; whilst for ship- ment to neutrals nothing below 50s. is named for both foundry and furnace coke, and very little export business is passing. IRON. Cleveland pig iron is rather quieter, most of the June home needs for foundry quality having been allocated, and recent deliveries of forge having been on a scale sufficient to enable customers to accumulate a little stock, but there is still a moderate home business passing, and there is more activity on foreign account. Facilities for distribution continue to show marked improvement. Not only is the truck situation very much better, but plenty of tonnage is now coming forward, and there is good ground for con- cluding that this month's deliveries will be heavy. For home consumption, No. 3 Cleveland pig, No. 4 foundry, and No. 4 forge are all quoted at 95s.; and No. 1 is 99s.; and for shipment to France and Italy No. 3 and the lower qualities are 114s.; and No. 1 is 119s. Conditions as regard the east coast haematite department are somewhat more satisfactory. Supplemented by supplies of basic iron and scrap, home customers’ needs are receiving adequate atten- tion, and a little more haematite is becoming available for export. There are still more complaints, however, that the quantities obtainable for shipment fall short of The quantities licensed for which tonnage is to be found. Nos. 1, 2 and 3 haematite are 122s. 6d. for home use, and 147s. 6d. for export to France and Italy. Very great activity characterises all branches of the manufactured iron and steel industries, and producers, though working at full pressure, are not quite able to fully cope with the huge requirements of the Government, and the enormous demands of the ship yards.