•IwrviiY 28, 1916. THE COLLIERY GUARDIAN. 183 CURRENT SCIENCE AND TECHNOLOGY. Coal Consumption per Indicated Horse-Power Hour and per Drawbar Horse-Power Hour. In connection with laboratory tests of a Consolidation locomotive by Schmidt, Snodgrass, and Keller (Univer- sity of Illinois. Bulletin, Vol. 13, No. 2), the curves of fig. I show the relation between speed and the amount of dry coal consumed per indicated horse-power per hour. Each of the curves there drawn applies to a particular cut-off. In a similar manner the relation between speed and the dry coal consumed per drawbar horse-power per hour is presented in fig. 2. The most economical performance was obtained in test 2075, made at a speed of 10 miles per hour and at 32 per cent, cut-off. During this test 4 lb. and 4’62 lb. of dry coal per indicated horse-power hour and per drawbar horse power hour respectively were used. The highest coal rate Fig. 1.—Relation between Coal Consumed per LH.P. Hour and Speed, at Various Cut-offb. rdrQ I .2 i £ Pl o IS ZJ ft 7 & $ 5 24%CUTOf/ 4 3 5 11 [) 1 20 2 3 Iff 4 4« SPEED—MILES PEE HOUR 5 20 30 9 I 7 I SPEED—-MILES PER HOUR Fig. 2.—Relation between Coal Consumed per Drawbar H.P. Hour and Speed, at Various Cut-offs. occurred in test 2089, made at a speed of 40 miles per hour, and at 40 per cent, cut-off, during which 7’10 lb. and 8'38 lb. of dry coal per indicated horse-power hour •and per drawbar house-power hour respectively were used. Both figures show a more rapid increase in coal consumption with increase of speed at long cut-off than with increase of speed at short cut-off. The curves show that economy was fairly constant, or increased slowly as speed was increased from 10 to 20 miles per hour. Tests at 24 per cent.’ cut-off show an economy apparently better at 15 to 20 miles per hour than at 10 miles per hour. As speed increased .above 20 miles per hour the coal consumption increased more rapidly than at 1 ewer speeds, with the exception of the tests made at 16 per cent, cut-off. Acetylene Air Explosions in Mines. With the increasing use of acetylene in mines, there has arisen the question of the danger of its exploding in the mine from various causes. There may first be considered the quantity of calcium carbide necessary to furnish explosive proportions of acetylene. The 4*6 cu. ft. of acetylene from 1 lb. of calcium carbide will yield 182 cu. ft. of air explosive on the assumption that the low explosive limit of acetylene air mixtures is 2-53 per cent, acetylene. Such an accident as the dropping of calcium carbide in a pool of water on the floor would result in a rich mixture near the water, the mixtures gradually becoming poorer as the acetylene diffused into the air, or was swept away by the venti- lating current of the mine. The ignition of acetylene produced under such conditions would result in the for- mation of a flame confined to a much smaller space than the dimensions given. The calcium carbide in a miner’s lamp (about 50 grammes), upon contact with water, would produce. 0’51 cu. ft. of gas, which could render about 21 cu. ft. of air explosive if the acetylene could be confined to a space of that size, which is not probable. With regard to the formation of acetylene from the action of the moisture in the mine air on calcium car- bide ■ thrown on the floor, a space 18 ft. wide by 30 ft. long by 7 ft. high would contain 3,780 cu. ft. of air. This space, if the temperature wans 65 degs. Fahr., and the saturation 90 per cent., would contain 1,495 grammes of water, enough to react completely with 2,660 grammes of calcium carbide, producing about 27 cu. ft. of acetylene. The production of acetylene in this manner would be too slow, however, to form an explosive mixture with air, because the acetylene first formed would be continu- ously carried away by diffusion and air currents, and consequently there would not result the accumulation necessary to form an explosive mixture. On the whole, with reasonable precaution, there need be little danger from explosion of acetylene in mines, though such an explosion may happen, as in the following instance. A miner carrying calcium carbide in a glass bottle stumbled and fell. The bottle broke, throwing the carbide into some water on the floor. Acetylene was immediately generated, and was ignited by the miner's cap light, severely burning him. Such an accident is a rarity. The following experiments were made by Messrs. G. A. Burrell and G. G. Oberfell, of the United States Bureau of Mines, in order to determine the effect of pressure on the explosibility of pure acetylene :—Acety- lene was enclosed over mercury in a 100 c.c. glass vessel, and the pressure was slowly increased by means of a column of mercury to a maximum of 5 atmospheres. No explosion insulted. The experiment was twice repeated, and each time under a pressure of 5 atmo- spheres a mild explosion with the formation of much caibon resulted when a platinum coil in the gas was electrically raised to a white heat. Under the same* con- ditions, except that a small electric spark from an induc- tion coil was used as the source of ignition, the gas exploded with great violence at a pressure of 3 atmo- spheres. Experiments were then made to determine the effect of increased initial pressure on the low explosive limit of acetylene air mixtures. It was found that, with an initial pressure of as much as 5 atmospheres, the low limit obtained, between 2-82 and 3 per cent, acetylene (ignition from the top) is not different from the value obtained wdth an initial pressure of I atmosphere. When acetylene was mixed with air, so as to form 10, 20, 30, 40, 50, 60, 70, 80, and 90 per cent, acetylene mixtures, no explosion resulted from compressing the mixtures to 1, 2, 3, 4, and 5 atmospheres. No means of ignition, such as an electric spark or a heated platinum wire, was used. The experiments showed that the smallest pro- portion of acetylene capable of propagating flame in a mixture of acetylene and air was 2-53 per cent., the largest proportion being about 73 per cent. Acetylene, not mixed with air, is explosive under a pressure of 3 to 5 atmospheres, when an electric spark is passed through the mixture, or wdien a platinum spiral is heated in it. The danger connected wdth the handling of calcium carbide in a mine is remote if reasonable care be observed in handling. Notes from the Coal Fields. [Local Correspondence.] South Wales and Monmouthshire. Coal Shipping Charges at Swansea—Cardiff Chamber of Commerce : Important Debate on Freight Rates—Custom of Sunday Night Repairing Shift—Fire at Blaenserchan Colliery. The anticipation that the payment of £65,000 by Swansea Corporation to the Harbour Trust would avert the need for raising coal rates has not been realised; and, therefore, a deputation representing the Chamber of Commerce waited upon the Trustees to point out that the increased rate for coal shipment from 2d. to 2^d. is objectionable. The president of the Chamber (Mr. T. P. Cook) said that the increase might occasion diversion of traffic. Sir Griffith Thomas (chairman of the Trustees) replied that the increase was unavoidable during the war, and it would continue as long as the war lasted, and probably for six months afterwards. A long dis- cussion took place between the members of the deputation and the-Trustees, and finally the question was adjourned for further consideration at the next meeting of the Trustees, but there seemed to be a general impression that no alterna- tive existed to the increase of the rate. The Cardiff Chamber of Commerce has had a two-days’ sitting this week to discuss the very serious question of limit- ing rates of freight, which have so detrimental an effect on the coal trade. The discussion was opened on Tuesday by Mr. T. E. Watson (president), who said that the ever- increasing rise had become so great that the council, of the Chamber decided to give consideration to the matter. Facts had come to their knowledge, making it absolutely necessary for the successful conduct of the war that the enormous burden placed upon our Allies, more especially in the cost of coal for the railwavs and manufacture, of munitions.. should be reduced. The evil had reached a pitch at which it must be dealt with unless it caused them to stop short of complete victory. He believed the ship owners would recognise that the rise in freights had gone too far; yet, since he previously spoke upon the matter, two months ago. there had been a further rise of from 25 to 50 per cent. He believed that the owners themselves would welcome any scheme which would remedy the evil, without transferring the profits from their pockets into the pockets of the neutral ship owner. Rates were now eight to 10 times those current before the war; and ship owners were receiving £150 to £200 a day demurrage, whereas before the war the rates were £20 to £30. Rates to Havre had risen from Is. lid. in 1914 to 22s. ; to Genoa from 7s. l|d. to 79s.; and to Port Said from 7s. lid. to 90s.; whilst homeward rates from Rangoon had risen from 22s. 6d. to-170s.: and from the Plate they had risen from 13s. 6d. to 150s. In the latter case, it had been calculated that the increase in freight alone was equivalent to a rise of 2Jd. in the cost of a 4 lb. loaf. Mr. Watson made some comparisons of specific instances, and showed that in one case, where a comnlete voyage of a vessel before the war left £648 profit, in a similar complete voyage after the war the profit was £13,702; and upon pre- sent-day rates it was calculated that a compi le vevage of that vessel would make £42,000 in 120 to 130 da vs. In the case of another steamer, which he named, built at a cost of £42.000 and worth after depreciation £35,280, he shewed that it had Iwen chartered on a 12 months’ time-charter, which would yield in 12 months £109,728. That, he estimated, would leave a profit of £85,000 on the original cost of £42.000, or. roughly, 200 per cent. Half of the excess profits would, of course, be paid over to the Government, leaving a net profit of £45,000, and if she had been chartered by the Government at present rate of 11s., she would yield a profit of £11,000, as against £45,000.' Dealing with the suggested remedies, Mr. Watson said that three proposals had been made. One was that the Government should requisition the whole of the tonnage of the country, and let it out at voyage rate propor- tionate to the Government rate of time charter. That pro- posal had been rejected by the President of the Board of Trade on the ground that it would aggravate the dearth of tonnage. Another proposal was that ship owners’ profits should be limited to 20 per cent., rates of freights to be regulated accord- ingly ; but this proposal would entail endless disputes. Both proposals were open to the still more serious objection that considerable time would be required to put them into shape, whilst the evil demanded an immediate remedy. The council of the Chamber therefore recommended that the Government should follow the precedent of the Price of Coal (Limitation) Act, and should introduce a Limitation of Freight Act, fixing rates at double those which were current for similar voyages at a similar time in 1912 ; and that the Government should also take over the whole of the insurance against war risk. The year 1912 had been taken because it showed the highest rates for seven years ; and double those rates would therefore yield a handsome profit. On that basis Genoa would be 23s., and the homeward rates from the Plate would be 46s. There should be a penalty for higher figures fixed; this to operate on anybody paying or receiving higher rates ; and that proposal would reach the neutral ship owner in 90 cases out of 100, whilst in the remaining cases the neutral competition could be met by a regulation of the Coal Exports Committee, that no neutral ship should receive coal at any port or coaling depot in the British dominions unless its Government had agreed to such limitation. He thought no colliery owner should get any profit advantage out of this limitation of freight. It was a scandal that foreign ship owners should be taking advantage of the protection of the British Fleet to draw profits of 200 per cent. Because the suggested limitation of freights would not increase the supply cf available tonnage, the council of the Chamber further recommended the prohibition of employing vessels on unneces- sary voyages; also the absolute prohibition of exports to neutrals in excess of their pre-war quantities: and prohibition cf all imports to this country other than foodstuffs and goods required for munitions of war, raw materials for manufac- ture, and, of course, pit wood for the collieries. The President then proposed a resolution carrying out the ideas he had set forth, and this was seconded by Mr. John Andrews, who referred to the serious state of things in Italy owing to the shortage of coal. The resolution also suggested that steps should be taken at once to increase the effective supply cf shinning by diminishing the extent to which vessels engaged by the Admiralty are now kept idle, and that the working of requisitioned ships should be subjected to the management of their owners, under the supervision of the Admiralty, just as the working of the railways is now left in the hands of the managers and directors/— Mr. R. O. Sanderson mentioned that there were ships in Cardiff unable to secure licences to take coal to Italy.—Mr. Andrews said, further, that there was no doubt the French people were feel- ing very strongly on the great cost of coal and other com- modities owing to the extraordinary height to which freights had risen. During the discussion it was pointed out that shipping was delayed at the different ports owing to the congestion of traffic due to the number of men who had enlisted; and it was urged that the Government should be prevailed upon to bring back men for this work, just as they had brought back skilled men for the manufacture of munitions. . Mr. T. Morel, ship owner, 'mentioned that there was no port from which the Government had levied a heavier requi- sition of tonnage than from Cardiff, the Hartlepools and Whitby not having been subjected to nearly such heavy calls. He considered that the crux of the question was the disposal of tonnage by the Admiralty, and said that he had figures showing that a certain ship, under Admiralty requisition, had spent one-seventh cf her time on sea and six-sevenths in port during the past 18 months. Mr. Vivian Rees (of Messrs. D. Davis and Scpis) argued that instead of suggesting to the Government to repeat the mistake they made in passing an Act to limit coal prices— an Act which had resulted in a loss to South Wales of seven to eight million pounds in the last seven months—should thev not suggest to the Government that, whilst freights were maintained at present figures'without any limitation, the excess profits should be modified so that out of the invisible exports they should get a rebate in respect of the imports of food- stuffs and ammunitions. During the second day’s debate, which took place on Wednesday, some striking instances of shipping delay were cited in respect of vessels requisitioned by the Government. Tn one case a vessel was five months in port before her cargo was discharged ; in another, the steamer was over 12 months on two cargoes; and, as a matter of fact, burnt the whole of her cargo except 800 tons. If ship owners worked their vessels as the Government had been doing, said Mr. D. Radcliffe, 12 months would see them all in bankruptcy. Mr. Beckingham said the persons greatly to blame for the increase in rates were the speculative middlemen in coal, who had got the wrong side of a bargain, and, losing their nerve, were bidding against each other for ships. Mr. P. H. Coward made a remarkable statement—that out of 50 vessels he had chartered during the past few weeks only one was British; eight were French; and the remainder belonged to neutral countries. In his opinion the vessels requisitioned by the Government could do four or five times the work they now did. Mr. W. J. Tatem, ship owner, said his firm’s profits during the first 12 months of the war totalled £191,395, whereas during the three preceding years they averaged £217,683. He considered that something should be done to make neutrals pay for all the advantages they gained from the British fleet. Resolutions upon the lines suggested by the president’s speech were agreed to. The Royal Humane Society has awarded bronze medals and certificates for the Glynea pit rescue. It will be remembered that a man was caught by a sudden fall of roof in the pit on November 15; and, finding it impossible to remove the debris, the rescuing party burrowed under- neath, and after working in dangerous conditions for ■three hours, succeeded in liberating him. Among those who received the medals and certificates was Mr. D. Meredith (under-manager), and Messrs. Evan Thomas, G. Davies, T. Daniel, and W. Howell (miners). The Pontypridd Stipendiary has given his decision in the case of the Albion Colliery, where a question was raised as to the Sunday night shift. A man was summoned for