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MINE VENTILATION.

Carbonic Oxide.

Symbol, CO. Equivalent, 14. Specific gravity, 0.9674.

$5.

5. One cubic foot of the gas at 32° F., and barometer of 30", weighs 0.078305 of a pound.

From

This gas is sometimes called "white-damp.” experiments made by Dr. Meyer and J. W. Thomas, it was found, that, during every explosion, large quantities of this gas were formed, and that the fatal effects of the after-damp are in a great measure due to its presence. Carbonic oxide is an odorless and colorless gas, incapable of supporting the combustion of other bodies, but is itself an inflammable gas. It possesses very poisonous properties, which act powerfully on the blood and nervous system, producing, when inhaled in very small quantities, a most unpleasant sensation, followed quickly by headache, and disinclination to move, prostration and inactivity: if continued to be breathed, asphyxia follows, and death soon results. Air containing only one-half per cent of this gas would prove fatal, if inspired for any length of time. Mr. Thomas advocates oxygen and induced artificial breathing, for those who are overcome by this gas, in preference to the administration of alcoholic stimulants.

is narcotic, and, when breathed in a concen

pain, the body passing Whatever position the

This gas trated form, would produce no instantly into a state of coma. victim assumed, in that position he would be found dead, unless moved by some other means. "Carbonic acid, and the nitrogen left after an explosion, would be fatal in their effects; but very often men have succumbed to supposed after-damp, while their lamps burned well. The presence of carbonic acid and nitrogen will not account for the result or phenomena.”

SULPHURETTED HYDROGEN.

Symbol, SH2. Equivalent, 17. Specific gravity, 1.178.

6. One cubic foot of the gas at 32° F. and barometer of 30", weighs 0.09492 of a pound.

This gas, although not common, is met with sometimes in mines. It is colorless, but easily distinguished by its peculiar smell, that of rotten eggs. It may be prepared by treating sulphide of iron with dilute sulphuric acid. The composition of sulphuretted hydrogen is,

When mixed with oxygen, it will explode if ignited. When inhaled in a pure state, it is a powerful narcotic poison, and produces fainting and asphyxia when present in very small proportions of the atmosphere. It appears to be probable that the gas is generated in small quantities in old worked-out mines. Some claim that it is formed by the decomposition of pyrites in old workings; others, that it is not formed in this manner, but by the decomposition of props and timber standing in water, by breaking up the sulphate of lime, and assimilating its oxygen, while sulphur seizes upon the hydrogen of the wood to form sulphuretted hydrogen. This gas is also known as hydrosulphuric and sulphuric acid gas.

MARSH-GAS.

Symbol, CH4. Equivalent, 8. Specific gravity, 0.55314.

7. One cubic foot of this gas, at 32° F. and barometer of 30", weighs 0.044665 of a pound.

It is known by several names,-proto-carburetted hydrogen, light carburetted hydrogen, hydride of methyl, fire-damp. Marsh-gas, however, is better known to

miners as "fire-damp." It is colorless, tasteless, odorless, when pure, burning with a yellowish flame. It is formed in swamps and marshy places by the decomposition of vegetable matter, and may be seen bubbling up through the water when the mud is stirred beneath. Marsh-gas is found in such quantities in some places, that it is used for lighting towns, and evaporating brine. In the oil-regions it frequently bursts forth with explosive violence, throwing the oil high in the air when the drill nears it. Coal-gas contains about thirty-eight per cent of marsh-gas. When marsh-gas is evolved in the shape of "blowers," it constitutes about ninetysix per cent of the total volume. Blowers sometimes assume enormous dimensions, and have been conveyed from the workings to the surface by means of pipes, and utilized. Marsh-gas is not poisonous. Sir H. Davy, of safety-lamp fame, was the first to experiment on this gas. He found, that, when mixed with three and a half times its volume of air, it did not explode; with five and a half times its volume, it exploded slightly; and, when mixed with eight or nine volumes of air, the force of explosion was greatest. When there is a deficiency of ventilation, the fire-damp is said to rise to the upper portion or top of a gallery, and there remain, because of its being lighter than air. It is also said that carbonic acid, being heavier than air, lodges on the "floor"

When mixed with oxygen, it will explode if ignited. When inhaled in a pure state, it is a powerful narcotic poison, and produces fainting and asphyxia when present in very small proportions of the atmosphere. It appears to be probable that the gas is generated in small quantities in old worked-out mines. Some claim that it is formed by the decomposition of pyrites in old workings; others, that it is not formed in this manner, but by the decomposition of props and timber standing in water, by breaking up the sulphate of lime, and assimilating its oxygen, while sulphur seizes upon the hydrogen of the wood to form sulphuretted hydrogen. This gas is also known as hydrosulphuric and sulphuric acid gas.

MARSH-GAS.

Symbol, CH4. Equivalent, 8. Specific gravity, 0.55314.

7. One cubic foot of this gas, at 32° F. and barometer of 30", weighs 0.044665 of a pound.

It is known by several names,

proto-carburetted hydrogen, light carburetted hydrogen, hydride of methyl, fire-damp. Marsh-gas, however, is better known to