140

0.—3

Coal. The coal lies to the westward of the limestone, and at a slightly higher elevation. Very little work has been done to open up the seam; the only places where it can be seen are in the different gullies, and in an adit-level driven in from the face of the hill, where it cuts the coal in the bottom, but the adit was constructed at too high a level to open out and work the seam. Very little can be said in reference to the coal, except what can be seen at the outcrops. These outcrops occur at Beid's Creek, and in several creeks and gullies. In some of these places there are three seams, with layers of mullocky clays and shale between, the largest of these seams being 7ft. in thickness. At some places the seam appears to be dipping at an angle of 45° to the westward, and in one place the seams are nearly horizontal, the latter place being in. the northern side of Bata Gully. The quality of the coal is similar to the brown coal found at Springfield, Whitecliffs, and Mount Somers, in Canterbury, and from all appearances there ought to be a sufficient deposit of it in this locality to justify it being opened up to supply coal for local consumption and for limeburning. It is very suitable for the latter purpose, as will be seen from its analysis : Fixed carbon, 4758 ; hydro-carbon, 39-95 ; water, 16-41; ash, 2-06 : 100-00. The evaporation-power is 6-191b. With regard to the value of the property, it depends to a great extent on the market that can be got for lime. Taking the close proximity of the coal and limestone, the natural facilities for burning lime and getting it conveyed to the railway, into consideration, it ought to be produced at a very low figure per ton.

SPONTANEOUS IGNITION OF COAL, AND ITS PEEVENTION. The question of spontaneous combustion in coal is one on which there is a great division of opinion. Many theories are set up as to the cause of spontaneous combustion which when they come to be analysed do not sufficiently account for all the circumstances. Some coals are not liable to spontaneous combustion; while with other classes of coal it is not safe to leave any fine dust, or it may be termed rubbish, lying in quantity in old worked-out bords, or even to carry it in cargoes. The coal found in the Waikato District and in many of the coal-mines in Otago is especially liable to heat and take fire. The earliest theory was that spontaneous combustion in coal was due to the oxidation of pyrites —disulphide of iron—into sulphates, but it has long since been proved that spontaneous ignition is not due to this alone, and that coal containing but a minute trace of iron-pyrites, but containing a large percentage of water, was far more liable to spontaneous ignition than coal containing a Large percentage of pyrites, which shows that the absorption of oxygen by the coal plays a prominent part in the question of spontaneous combustion. In the Colliery Guardian of the 18th, and also of the 25th March last, is published a paper read by Professor Vivian B. Lewes, F.L.S., F.C.S., before the Society of Arts on the 2nd March last, which contains a great deal of interesting matter on this subject, in which Professor Vivian states :— " Last autumn I had the honour of bringing before the Chemical Section of the British Association certain views, which are now widely gaining ground, as to the cause of the phenomenon of spontaneous ignition of masses of stored coal; and, in the discussion which ensued, Sir Frederick Bramwell expressed the hope that the paper would be followed by a second, in which methods for the prevention of this too often disastrous action might be discussed ; and it is at the invitation of your secretary that I propose to bring my views on the subject before you to-night. Ever since the general adoption of coal as a fuel, the storing and shipment of masses exceeding 2,000 tons has been recognised as requiring great care ; and if much small coal has been present, or if it has been stored wet, firing, or at any rate heating, of the mass has frequently taken place. On shore this has led to much inconvenience and loss, but it is during shipment that the real danger has occurred; and many a fine vessel, with all hands, has been lost from this cause, without even a record of the calamity reaching the land. In 1875 the loss of life and property from this cause became so serious that a Eoyal Commission was appointed to report upon the possibility of preventing these appalling disasters; but the recommendations contained in the report, although of the greatest possible value, seem to have had but little effect in checking the loss from spontaneous ignition ; and, in the nine years following the publication of the report (1873 to 1883), no less than fifty-seven coal-laden vessels are known to have been lost from this cause, whilst 328 others were missing. In coal stores, and in gasworks, heating frequently takes place, but is so much more easily dealt with than at sea that cases of absolute ignition are much rarer; and it is from the evidence obtained in the case of coal cargoes that we can learn most as to the cause and prevention of this most dire plague of the coal trade. In treating the subject to-night, I will first bring to your notice the explanation of the action which eventually results in combustion, and which is founded upon the work of Bichters and myself, and will consider how the incipient action can be best prevented, or at least retarded, and the steps which should be taken in case ignition should result. Coal is a substance of purely vegetable origin, formed out of contact with air by long exposure to heat and pressure, from the woody fibre and resinous constituents of a monster vegetation, which flourished long before the earth was inhabited by man; and coal may therefore be looked upon as a form of charcoal, which, having been formed at a temperature lower than that of the charcoal burner's heap, and under great pressure, is very dense, and still retains a quantity of those constituents which, in the latter case, are driven off as tar, wood naphtha, &o. These bodies consist essentially of compounds containing carbon and hydrogen, together with a little oxygen and nitrogen, and form the volatile matter and hydrocarbons of the coal. Besides the carbon and hydrocarbons, coal also contains certain mineral bodies, which were mostly present in the sap and fibre of the original vegetation, and which gives the ash which is left behind when the coal is burnt. These substances consist