146. SPONTANEOUS COMBUSTION. Any coal containing a large quantity of iron pyrites is apt to heat when saturated with water, and after some time to burst into flame; the only prevention is said to be to keep the coal dry. Some kinds of coal are free from iron pyrites, and therefore not subject to spontaneous combustion.
147. IGNITION. Every kind of steam and other coal, especially when rapidly transferred from the mine to the ship, gives out carburatted hydrogen gas or fire damp, which is explosive when mixed with atmospheric air, on the application of flame. This gas is peculiarly light, and is considered most explosive when mixed with nine times its volume of atmospheric air; with twelve times it will not ignite. If the hatches are fastened down directly the cargo is received, which is frequently done to keep out the rain or cold, or to prepare for sea, the gas finds its way from the coal to the spaces under the deck, and penetrates through the bulkheads into the lazarette, cabin, and forecastle, and when a match is lit, or a lighted candle is exposed, especially in the lazarette, an explosion may take place and damage the decks, and jeopardize the lives of the crew. To avoid this let two funnels, of 12 or 15 inches diameter, with moveable tops, be placed one forward, the other aft, communicating through the deck with the hold; keep a vacant space between the cargo and the beams. Turn the top of one funnel to the wind, the other from it, a current of air will then conduct the explosive gas harmlessly out of the ship; this is said to be an effectual remedy. It has been also suggested that coal may be ventilated by building, with large lumps, two shafts communicating below; one with a wind-sail would act as a down-cast for fresh air, the other as an out-cast for foul air. In addition to this keep the hatches open 24 or 26 hours, on all occasions, but especially when bound on long voyages, particularly to the south ward.
148. MR. MURRAY, when speaking of coal for engines, says "the best method of prevention, is to ensure perfect dryness in the coals when they are stowed in the bunkers, and to select a variety not liable to progressive decomposition." By the Queen's Regulations, 1862, captains of ships of war are instructed, in order to prevent accidents by fire from spontaneous combustion of coal, to see that the whole of the wood work of the coal boxes, whether it form part of the side of the ship, or otherwise, be securely lined with iron or copper sheathing. He is to order the greatest care to be taken that the cola is never shipped wet; and that, when shipped, it shall be kept as dry as possible. Whenever a fresh supply is received on board, directions are to be given that the remainder in the coal boxes, is, as far as may be practicable, so trimmed as to ensure its being first used. The Admiralty will not permit coal to be shipped as cargo in a vessel conveying a large quantity of government powder, ammunition, or combustibles.
149 Excepting the Aberdale Valley and some other sorts, which are free from iron pyrites, Brassey coal and steam coal, especially when damp, are, according to their chemical qualities, more or less liable to spontaneous combustion, and when coals from different pits are mixed, the danger is said to be increased. Every ship laden with this class of combustible goods ought to have a safety lamp for exclusive use in the lower hold, and under the cabin floor; few accidents occur, except through neglect or ignorance. On the 12th July, 1862, one of two laborers, Twinter and Thorpe struck a light in the hold of the coal-laden screw-steamer Florence Nightingale, at Hartlepool, when an explosion occurred. The two men were frightfully burnt, and a third named Mooney, who was descending the main hatchway, was thrown about three feet in the air, and fell on the deck; all the flesh was taken off his arms and breast. The steamer suffered no damage. On the 27th of April, 1866, the cargo of Shotton gas coal ignited spontaneously on board the screw steam-vessel Leipsic when near the mouth of the Humber, bound to Antwerp. Several of the crew were injured and she returned to West Hartlepool.
Transcribed by Lars Bruzelius
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