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one-fifth of its volume of oxygen, so that 60 cubic feet represent 300 cubic feet of air, or twenty-five times as much as is present. It is therefore evident that if the air could be excluded, there would be only one twenty-fifth the quantity of oxygen present that is needed for complete action, and any heating would, in consequence, be very slight, whilst to produce the greatest heating it would be necessary to change the entire air in the cargo twenty-five times in the first ten days, and this is just about what the old method of taking a box-shaft along the keelson with Venetian lattice upshafts from it would give. The most forcible illustration of the evil of such ventilation is to be found in the case of the four colliers, ' Euxine,' 'Oliver Cromwell,' 'Calcutta,' and ' Corah,'which were loaded at Newcastle under the same tips, at the same time, with the same coal, from the same seam. The first three were bound for Aden, and were all ventilated. The ' Corah' was bound for Bombay, and was not ventilated. The three thoroughly ventilated ships were totally lost from spontaneous ignition of their cargo, whilst the ' Corah ' reached Bombay in perfect safety. " 7. Bise in Temperature. —It has been fully pointed out that anything which tends to increase of initial temperature increases the rapidity of chemical action, and in most cases of spontaneous combustion in coals stored in this country, the cause can be traced to a steam-pipe or boiler-flue in contact with the mass of coal, or even fixed to a wall against which, on the other side, the coal is heaped. Sometimes the coal-store is close to the benches of retorts in a gasworks, or even against the wall of the benches, and in such cases, with certain classes of coals, ignition would be almost certain to take place. In a paper read at the last meeting of the Gas Institute, it was proposed to lead the flues from the benches under the coal store, in order to dry the coal, a device which would infallibly lead to spontaneous ignition. On colliers there are many causes for increased temperature, amongst them being the introduction of triple-expansion engines and high-pressure boilers. Steam at 801b. boiler-pressure has a temperature of 324° Fahr. (162° C), and a common stokehold temperature, with boilers worked at this pressure, is 100° to 130° Fahr. (or 38° to 54° C). Steam at a boiler-pressure of 1551b. has a temperature of 368° Fahr., or 186° C, and gives a corresponding increase of temperature in the stoke-hold and other adjacent portions of the vessel, the temperature in the stoke-hold under these conditions being from 110° Fahr. (43-5° C.) to 140° Fahr. (60° C), an increase of about 10° Fahr. Then, again, donkey-boilers will often be found recessed into bunker bulkheads, and steam-pipes led alongside the bulkheads, with the cargo close up against them on the other side. The effect of temperature due to climatic influences has already been dealt with under the influence on ignition of ports to which shipments are made. Precautions to be taken. " Having now discussed the chemical and physical conditions which lead to the phenomenon known as 'spontaneous ignition,' we can formulate precautions which will tend to prevent such disasters: — " 1. The Choice of Coal for Storage or Shipment. —The coal should be as large as possible, free from dust, and with as little ' smalls 'as can be helped. It is better as free from pyrites as possible, and it should contain, when air-dried, not more than 3 per cent, of moisture. "2. Precautions to be taken in Storing or Loading. —The coal store should be well roofed in, and have an iron floor bedded in cement. All supports passing through and in contact with the coal should be of iron or brick ; if hollow iron supports are used they should be cast solid with cement. The coal must never be loaded or stored during wet weather, and the depth of coal in the store should not exceed Bft., and should only be 6ft. where possible. Under no condition must a steam- or exhaust-pipe or flue be allowed in or near any wall of the store, nor must the store be within 20ft. of any boiler, furnace, or bench of retorts. No coal should be stored or shipped to distant ports until at least a month has elapsed since it was brought to the surface. Every care should be taken during loading or storing to prevent breaking or crushing of the coal, and on no account must a large accumulation of small coal be allowed. These precautions, if properly carried out, would amply suffice to entirely do away with spontaneous ignition in stored coal on land, and we have now to consider a far more important phase of the question. "3. Precautions to be taken on Board Coal-laden Ships. —This phase of the question is undoubtedy the most important, and in order to insure any successful treatment of the coal cargo at sea, to prevent undue heating and ignition, the means adopted must be as nearly automatic in their working as possible, as it is useless to expect the master or any officer on board a collier during rough weather, &c, to comply with any instructions, such as daily taking the temperatures in various parts of the cargo, and so on. The iron bulkheads dividing the coal storage from the other parts of the vessel should be made double, and spaced 6in. to Ift. apart, with openings (which could be closed water-tight) every few feet, to allow of the interior being from time to time coated with protective compositions. Through this double casing sea-water would be allowed to circulate, and would not only effectually prevent any penetration of heat from the stokehold, boilers, or engineroom to the coal, but also do away with any chance of leakage of gases from the coal cargo into other portions of the vessel, and so would minimise the danger of explosions. A similar double partition should run down the centre of that portion of the vessel in which the coal was stored, and it would be sufficient if this were packed with silicate wool; this partition would serve to prevent any heating which might take place in one part of the cargo being communicated to the other half, whilst it would also perform the important function of helping to prevent shifting of the cargo during heavy rolling. When the coal has all been taken in it should be battened down, and the hatches should not be again opened until the vessel reaches her destination, the only ventilation allowable being a 2in. pipe just inserted into the crown of each coal compartment, and led 12ft. up the nearest mast, the top being left open. This would be quite sufficient to allow free egress to any gases evolved by the coal, but would not allow undue excess of air. Into the body of the coal cargo itself would be screwed, at regular intervals of about 10ft., iron pipes, closed at the bottom and containing alarm thermostats, so