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Theory of the Distillation of Coal. — On the question of the distillation of coal during an explosion of firedamp, I consider that such a theory is unnecessary to account for the Haig Pit disaster, in view of our knowledge of the phenomena associated with explosions of firedamp and coal dust.

If such distillation takes place, it is quite impossible for any distillation products, the result of the action of the firedamp flame, to be in advance of that flame. If and when distillation occurs it can only be due to the heated gases behind the flame. I am of opinion, however, that there is a field of research open to ascertain if distillation of the coal sides of roads really does occur and, if so, in what circumstances.

Another important point that arises on considering the evidence is the question whether 30 per cent. of moisture is sufficient to prevent propagation of flame by coal dust. It seems to me that this must largely depend upon the extent of the initiating cause; that is to say, if there is a considerable amount of heat generated by an explosion of gas, 30 per cent. of moisture might prove to be insufficient, but if the ignition of gas is of smaller degree, that percentage of moisture might prove sufficient. Similarly, there is 50 per cent. of combustible matter in the dust, the mixture might prove ineffective, by not arresting the flame in the event of the ignition of a considerable body of gas. These are points well deserving the attention of the Safety in' Mines Research Board.

Shot-firing and Precautions against Coal Dust. — As regards the question of blasting operations, the Agent, Mr. Steel, gave me a personal undertaking soon after the explosion occurred and before the Inquiry opened, not to resume the use of explosives in the Six Quarters Seam, and spoke of substituting holing and shearing machines in its place. Meanwhile the question of producing, if possible, a "flameless" explosive, or at all events one the flame of which cannot ignite firedamp or coal dust in mines' is already engaging the attention of a Committee appointed by the Secretary for Mines on the recommendation of the Safety in Mines Research Board.

Clause 5 in Part II of the Explosives in Coal Mines Order of the 1st September, 1913, requires that (a) "in all coal mines in which inflammable gas has been found within the previous threemonths in such quantity as to be indicative of danger, no explosive, other than a permitted explosive as hereinafter defined, shall be used in or taken for the purpose of use into the seam or seams in which the gas has been found," . . . and that (b) "In all coal mines which are not naturally wet throughout, no explosive, other than a permitted explosive as hereinafter defined, shall be used in or taken for the purpose of use into any road or any dry and dusty part of the mine, or any shaft or drift communicating therewith." The same Order also stipulates in Clause 6 (f) (iii) that in such mines as are described above "No shot shall be fired unless the shot-firer has examined the floor, roof and sides of all contiguous accessible places, within a radius of 5 yards of the place where the shot is to be fired, for coal dust, and has taken efficient steps to render any dust within that area harmless."

As has already been mentioned, the explosive in use in the Haig Colliery was of the "permitted" class. As regards the treatment of any dust within a radius of 5 yards of the place where a shot was fired, no steps were taken because the dust within that area was considered to be harmless by reason of the natural dampness of the seam. I have grave doubts whether all the dust created within the 5 yards area of the places where shots were fired was as harmless as it was thought to be. I have little faith in natural dampness when an explosion of firedamp occurs, unless the place is sopping wet.

The amount of fine dust produced in the different operations of coal getting varies in different mines. The quantity which in the presence of flame may prove dangerous is so small as to be scarcely perceptible, and as so many explosions have originated through blasting operations and those operations are so extensively carried on in many mines, there is, in my opinion, good ground for requiring the dust to be treated whether the shot-firer considers it to he harmless or not.

The General Regulations dated 30th July, 1920, as to Precautions against Coal Dust, require steps to be taken in "every road or part of a road" and term "road" includes all roads of any description extending from the shaft or outlet "to within 10 yards of the coal face" ; Clause 6 (f) (iii) of the Explosives in Coal Mines Order, which operates only when a shot is about to be fired, provides for efficient steps to be taken to render dust harmless within a radius of 5 yards. It follows, therefore, that when a shot is fired at the coal face of a heading, there is a zone of 5 yards which, so far as the law is concerned, requires no treatment at all. I recommend, therefore, that Clause 6 (f) (iii) of the Order should he amended so as to require that any dust within a radius of tan yards of the place where a shot is to be fired shall he thoroughly stone dusted or otherwise efficiently treated so as to render it harmless. Meanwhile, managers of mines where blasting operations are in progress would be well advised voluntarily to adopt this course if and where it is not already being done.

The General Regulations already referred to do not apply to mines of which the floor, root and sides of the roads are naturally wet throughout," owing to the exception in Regulation 1. It was contended by the management of the Haig Pit that the mine was naturally wet throughout," but it was admitted that stone dusting was necessary, and was carried out in the roadway leading to the district affected by the explosion, and that certain places in the South district in the same mine had become dry "a few months ago." In these circumstances the management was not in my view justified in regarding the mine as being "naturally wet throughout."

Put briefly, the General Regulations provide that, unless the roof, floor and sides of every road or part of a road which is accessible are naturally wet throughout, they must either be treated with incombustible dust in such manner as to ensure that the dust on the floor, roof and sides throughout shall always consist of a mixture containing not more than 50 per cent. of combustible matter," or they must be treated with water in such manner as will ensure that "the dust on the floor, roof and sides throughout is always combined with 30 per cent. by weight of water in intimate mixture" ; and further, that representative tests "shall be made by the Management at intervals of not less than once a month and the result shall be posted at the pithead." It was admitted that, while samples of dust were taken in the drift at the top of the Engine Plane and in the South District, no really satisfactory test was made of the dust in the North District to ascertain whether or not it contained 30 per cent. of moisture. The failure to make representative tests in the manner prescribed for moist dust mixtures, Order No. 201 of 7th February, 1921, constituted a contravention of the Regulations referred to.

It is not sufficient to judge the moisture by simply looking at, or feeling the dust, which was apparently the only method adopted by the management in the area affected by the explosion, and it is necessary, even where it is considered that the floor, roof and sides of every road or part of a road which is accessible are naturally wet or are treated with water, to carry out the prescribed test for moist dust mixtures. In the same way, it is necessary where the dust on the floor, roof and sides of such roads is considered to contain not more than 50 per cent. of combustible matter, to prove the fact by representative tests.