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wire of ith heated to the same degree, will inflame olefiant gas; but a wire of both 'must be heated to whiteness to inflame hydrogen, though at a low red heat it will inflame bi-phosphuretted hydrogen gas; but wire of mth, heated even to whiteness will not inflame mixtures of fire-damp.
A tissue which will not interrupt the flame of hy. drogen when red hot, will still intercept that of olefiant gas; and a heated tissue which would communicate explosion from a mixture of oefiant gas and air, will stop an explosion from a mixture of fire-damp or carburetted hydrogen.
Sir H. Davy states—“I first began with a minute chemical examination of the substance with which I had to contend. The analysis of various specimens of fire-damp shewed me that the pure inflammable part of it was light carburetted hydrogen gas, as Dr. Henry had before stated; hydrogen or pure inflammable air combined with charcoal or carbon. I made numerous experiments on the circumstances under which it explodes, and the degree of its inflammability. I found that it required to be mixed with very large quantities of atmospheric air to produce explosion; even when mixed with three or nearly four times its bulk of air, it burnt quietly in the atmosphere, and extinguished a taper. When mixed with between five and six times its volume of air, it exploded feebly; it exploded with most energy when mixed with seven oreight times its volume of air, and mixtures of fire-damp and air retained their explosive power when the proportions were one of gas to fourteen of air. When the air was in a larger quantity, the flame of a taper was merely enlarged in the mixture, an effect which was still perceived in thirty parts of air and one of gas.*
“On mixing one part of carbonic acid or fixed air with seven parts of an admixture of fire-damp, or
Davy on Flame, p. 10.
one of azote with six parts, their powers of exploding were destroyed."*
. Since the time of Davy, nothing more has been brought before the public as to the degrees of explosive power of different mixtures of fire-damp and air. I don't for a moment question the law of the diffusion of gases, so beautifully proved and developed by that distinguished chemist Professor Graham, but in coal mines, most assuredly in a dead place, a stratum of fire-damp is often found occupying the top part of the mine, a stratum of air the middle, and a larger of carbonic acid or choke damp at the bottom. I have seen a Davy lamp burn well in the middle part, but when quietly put up into the fire-damp above, or the choke-damp below, it has been extinguished, thus clearly proving the existence of three strata of gases lying in a position which their specific gravities would indicate. I have also seen a light applied to the upper layer of fire-damp which was not in large quantity, and a wave of flame rolled on from one extremity of the working to the other without producing an explosion; thus proving Mr. Taylor's opinion expressed in the Report of the South Shields Committee, that so far as his observation went, no practical data of value can be deduced from the law as to the diffusion of gases, when applied to what occurs in mines.*
In many cases there can be no doubt where the fire-damp comes from. It is evident that it pours out of a “blower," or issues from the face of the coal, as it can be heard hissing out with great noise and forcing off pieces of coal in its eagerness to get out; but in other instances it suddenly makes its appearance with the air, and fouls a place previously clear of gas in a short time. A great many fatal accidents have occurred from these sudden visitations of fire-damp which come upon the miner like a thief in the night.
Ibid, p. 11.
Nothing is more evident in an explosion of firedamp than the great rush of air that blows down the stoppings and hurls on the tubs and wagons with great force. This arises from the expansion of the gases during the explosion. The following table will shew the results of an explosion :Explosive Gas. Composed of
2 vols. Hydrogen... 2 of Aqueous Vapour.
i Carbonic Acid.* The expansion of these gases by the explosion is about 31 times the original bulk. The life sup.
: porting principle of the air, oxygen, uniting with hydrogen and carbon, forms water and carbonic acid, and nothing is left for the miner to breathe but a stratum of nitrogen in the middle and top of the mine, and a layer of poisonous carbonic acid or black damp at the bottom. The effect of nitrogen on the lungs is not well known, but the 10 per cent. of carbonic acid is quite sufficient to cause death, especially as the men on an explosion generally fall down to the bottom of the mine, and thus come into a layer of nearly pure carbonic acid. On hearing the blast of an explosion approach, the men generally fall flat down, so as to allow the blast to pass over them, but when this has gone over, the sooner they
up their heads to the middle and upper, but not the highest part of the working, the better, as they are likely to get out of the carbonic acid gas, and find any remnant of air that may by chance be left. The appearance of persons killed by after damp is somewhat different from those destroyed by choke damp; no doubt death results partly by obstruction in breathing and partly by imbibing choke damp, which is well known to be a strong narcotic poison. The remedies for persons who have inhaled either
* South Shields Report of Accidents in Coal Mines, p. 69.
choke or after damp, as given by the French authorities, are the following, which may be of service antil the arrival of a medical man, who ought to be sent for as soon as an accident occurs:
1st. Draw the person promptly from the deleterious place, and expose him to good and pure air.
2nd. Undress him and throw on the body effusions of cold water.
3rd. Try to make him swallow, if it be possible, cold water slightly acidulated with vinegar.
4. Clysters should be given, two-thirds of cold water and one-third of vinegar; afterwards to be followed up by the administration of others with a strong solation of common salt, or of senna and Epsom salts.
5th. Attempts should be made to irritate the pituitary membrane with the feather end of a quill, which should be gently moved in the nostrils of the insensible person, or stimulated with a bottle of hartshorn put under the nose.
6th. Introduce air into the lungs by blowing with the nozzle of a bellows into one of the nostrils, and compressing the other with the fingers.
7th. If the above measures do not produce any effect, and the body preserves its heat, recourse should be had to blood-letting, of which the necessity will be clearly indicated if the face be red, the lips swollen, and the eyes protruding. Blood-letting in the jugular vein will produce the speediest effect; in default of drawing it from that place, it should be drawn from the foot.
8th. For the last resort an opening should be made in the trachea, and a small pipe should be introduced, through which the air should be pressed by the aid of a little bellows.*
Having thus slightly brought before your notice the gases generally found in coal mines, described some of the lamps now in use, shewn the priuciples upon which they are constructed, and alluded to other matters, let me add in conclusion, that it is the interest as well as the duty of the proprietor of mines, to use every means that science and practical skill can devise for the safety of their workmen. There is no fear of having too much of these qualifications in the officers of mines. A manager of a colliery employing a thousand men engaged in a fiery mine, has far more responsibility, and surely requires as much skill and science, as the colonel commanding as many men above ground in the open air; and if intelligence, sobriety, and discipline are essentially requisite for officers and men in the army, how much more necessary are these qualities in a mine amongst invisible and intangible enemies like gases? It is not now my business to urge on masters what they ought to do, --but I do say to the workmen that much of their safety will always depend on strictly observing the orders of their officers, and doing all they can to preserve discipline; for without this there can be no safety in a mine. Of all men in the world a collier ought to be a sober, steady, careful, and observant man.
* South Shields Report of Accidents in Coal Mines, p. 73,
THE CHARMS OF LIFE.— There are a thousand things in this world to afflict and sadden-but oh, how many that are beautiful and good! The world teems with beauty-with objects that gladden the eyes and warm the heart. We might be happy if we would. There are ills which we cannot escape -the approach of disease and death, of misfortunes, sundering of earthly ties, and the canker worm of grief, but a vast majority of the evils that beset us might be avoided. Let wars come to an end, and let friendship, charity, love, purity, and kindness, mark the intercourse between man and man. We are too selfish, as if the world was made for us alone. How much happier should we be were we to labour more earnestly to promote each other's good. God has blessed us with a home which is not all dark. There is sunshine everywhere -in the sky, upon the earth—there would be in most hearts if we would look around us. God reigns in Heaven, Mur. mur not at a creation so beautiful. --Bishop Hall.