11^th January 1861

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The Hetton Colliery Explosion

Hetton, Jan. 9.

The adjourned inquest on the bodies of the 23 stonemasons killed in Hetton Colliery on the 20th of December has been re-opened here, and is likely to extend over two or three days. Mr. Dunn, mining inspector, Mr. Northumberland, and Mr. Dickinson, mine inspector for the Manchester district, are in attendance, the latter at the request of the Home Secretary. The evidence of several overmen and others has been taken as to the circumstances of the explosion in the mine, the loss of the lives of the 23 men, and the recovery of their bodies. These particulars have already been recorded. There had been no appearance of any gas in the pit immediately before the explosion, and from the condition of the mine, as soon as it could be examined after the fire, it was demonstrated that the blast must have originated in the flues of the boiler near to the West Miner's shaft, where, in the language of a pitman, everything had been "blown to bits." Mr. Isaac Lowthin Bell, an alderman of Newcastle, and an eminent ironmaster and chymical manufacturer, has given very instructive evidence as to the cause of the explosion. Mr. Bell, in his evidence, said, — Having in my business something like 30,000 cubic feet of gas per minute to contend with, I have necessarily been induced to study the effect of explosive mixtures more than I otherwise should have done. I went down the downcast shaft of the West Miner Pit this morning. I spent two hours or more in examining the flue in which the explosion is alleged to have taken place. In the first place, I found a damper within about six feet from the boiler. It was broken in two ; the lower portion resting in its place, the upper portion, as one might have expected from the counterbalance weight, drawn downwards. Close to the boiler I found a jacket burned. I found some woodwork opposite to the boiler charred, and woodwork and stone blown eastward from the boiler. I saw it was blown down, indicating the direction of the explosion to have proceeded from the boiler. I found 30 feet of flue from the damper boards of the upcast shaft blown out. I found the whole of the lateral flues in the pipe drift blown outwards. From that point, for about 20 feet, the flue and travelling ways were whole, arising, no doubt, from the greater strength of the flue, or less intensity of the explosion. There were about 15 feet of the top of the flue blown outwards, and about 10 feet of the covering of the travelling ways also displaced. This brings us to the crossing over the northway. Here, the flues being unsupported either one side or the other, burst the whole thing ; that is, the walls on the north side were blown to the north, and those on the south side were blown to the south. There was nothing to resist ; and, generally, the indication of the explosion at this place was as if the explosion had proceeded from the crossing as a common centre. From that I continued along the flue towards the furnace going to the upcast shaft. The soot had evidently been displaced from one end to the other. At the end next to the furnace, there was a little displacement of brickwork. At the end of the north furnace a bridge of brickwork was blown over in that direction, which an explosion in this flue would render probable. Immediately opposite there is a drift proceeding from another furnace, in which, where it crosses the road, I found the arch displaced. I may state that the only questions which presented themselves to my mind are — first, whether, under any circumstances, a flue so situated, and so constructed, could have contained within itself the elements of such an explosion ; and, secondly, where did the gas come from. Perhaps I may be allowed to answer the latter question first. I arrived at the conclusion that the gas could not come from the workings, because the boiler furnace always has been, and is now, exclusively fed by air proceeding direct from the downcast shaft, without going into the coal workings. I find, by computation, this flue contains 7,000 cubic feet. I find, to fill a flue with light carburetted hydrogen, leaving a sufficient content for the necessary atmospheric air to thoroughly explode the light carburetted hydrogen so contained in the flue, 152lb. of fresh coal would furnish the whole gas necessary.

By Mr. Dunn. — The length of time to do that would depend upon the heat applied.

Examination resumed. — I find to fill the same flue with another explosive gas (carbonic oxide) 49lb. of coke would be sufficient. Supposing, then, the flues were filled with either of these gases, together with the necessary atmospheric air required for the explosion ; supposing this flue filled at a time when there was no matter sufficiently heated to cause the explosion — a state of things which might readily occur from damping the coals — then the combustion of the coal at the boiler end, or the furnace at the far end, either one or both, could supply the flame for setting on fire this magazine of inflammable gas. Now, the next question is, supposing that to have taken place, is this damage of a character to have ensued from such an explosion ? I may state that in my own experience I had a wrought iron pipe, three feet in diameter and about 100 yards long, filled with an explosive compound, in which the combustible gas was carbonic oxide, the less explosive of the two. In round numbers, it has about half the power of light carburetted hydrogen. That pipe, fired at one end at a lamp, blew the man holding the lamp many yards into the air, breaking every bone in his body, destroyed almost the whole length of iron pipe, and split the blowing apparatus of metal, three-quarters of an inch thick at the far end. Consequently, my opinion is based upon these facts, and upon philosophical calculation of the power of such a quantity of gas, or much less. All the results that I have this day seen are easily accounted for. As soon as ever the contents of the flue took fire, supposing it to be filled with an explosive mixture of light carburetted hydrogen, the 7,000ft. contained in it would instantly become 60,000 cubic feet. Of course, that increased volume would run down any point to which it would gain most ready access. (Some of the bodies were found in a straight line from the place of the probable origin of the explosion.) But in addition to that, the contents of this place would be instantly converted into after-damp, and this being taken up by the natural ventilation of the colliery, would be carried into the workings, and thus cause the death of every man over whom it passed. I think it highly probable the explosion might have set fire to the north stables, a distance of 350 yards, not because flame would travel that far, but because particles of inflammable matter set fire to by the explosion would be driven in the direction of the stables ; and, besides, the temperature of these exploded gases being about 1,500 degrees of Fahrenheit, or a very bright red heat, would of itself, if coming near hay or straw, immediately set fire to it. In this way I think everything that has occurred can be fully accounted for, as far as I have seen. It is quite my opinion that this explosion could have been caused by some quantity of gunpowder ; but it would take 75 quarter barrels of 25lb. each to produce anything like the effect you have here. It is perfectly impossible, а priori, to know how much gas has exploded ; but, seeing and knowing the manner in which the explosion is generated, then we have the means of coming to the amount.

By Mr. Dickinson. — In my calculations I took a ton of coal to produce 10,000 cubic feet of gas, and about 650 feet of light carburetted hydrogen are produced by 160lb. I add to it 9½ times the atmospheric air ; that is 6,330ft. of explosive mixture. Assuming no steam to be present, no quantity of soot deposited in this flue could have added to the violence of the explosion. Assuming that steam was present, then I think it possible that the explosion might have been increased somewhat in intensity. I think it probable that the flue ascending from the boiler fire, including the crossing, the gas would have lodged in it. All calculations based upon the difference of specific gravity of gases are liable to disturbance by differences of temperature, by which means a cubic foot of heavy gas may be rendered lighter, or as light as a cubic foot of lighter gas. If the gas was only contained in that part of the flue, it would reduce the gas to about 3,000 cubic feet.

The Coroner. — That would be sufficient to cause the explosion. The quantity in my own case was between 1,000ft. and 1,200ft.

Examination resumed by Mr. Dickinson. — The gas, either over-saturated or under-saturated with air, would be quite equal to the effects produced.

By the Coroner. — After the crossing had been blown down, a larger amount of air would be admitted to mix with the hydrogen gas. I doubt whether it would increase the intensity of the explosion. It would depend on collateral circumstances.

Mr. Dickinson. — There is no reason that suggests itself to me for the gas accumulating in this way and exploding, when it has not done so for so many years before. It is one of those things affected to some extent or the doctrine of chances ; that is, you require inflammable gas, atmospheric air, and fire contemporaneously. Any one of these wanting, no explosion ensues. The frosty weather, I think, would not render the explosion more violent. I do not attribute any importance to the frost.

By Mr. Dunn. — If the damper had been hermetically sealed, inflammable gas would not be found there.

The Coroner. — Its being partly opened would accelerate the generation of gas, and would also supply air.

By Mr. Dickinson. — In my opinion, the explosion cannot have taken place in any other way than I have explained, from the direction in which the materials are lying, and from the other appearances in and about the flue. Supposing a large quantity of fire-damp had come from any of the upper workings down the downcast shaft, and passed over, not through the fire, and filled the flue beyond, a similar explosion might have taken place.