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METHODS OF OBTAINING H1DROGEN GAS.

affinity, that of the oxigen of the water with the metal, and thatof its hidrogen with caloric.

The more caloric is employed in the experiment of decompos-ing water by means of iron, &c. the sooner is the water de-composed.

Hidrogen gas is frequently found in great abundance in minesand coal-pits, where it is sometimes generated suddenly and be-comes mixed with the atmospheric air of these subterraneous ca-vities. If a lighted candle be brought in, this mixture oftenexplodes and produces the most dreadful effects. It is called byminers fire-damp. It generally forms a cloud in the upper partof the mine on account of its levity, but does not mix there withatmospheric air unless some agitation takes place. The minersfrequently set fire to it with a candle, laying at the same timeflat on their faces to escape the violence of the shock. An easierand more safe method of clearing the mine is by leading a longtube through the shaft of it, to the ash-pit of a furnace; by thismeans the gas will be conducted to feed the fire.

Hidrogen gas in whatever manner produced, always originatesfrom water, either in consequence of a preceding decomposition,in which it had been combined in the state of solid or fixed hi-drogen, with one of the substances employed, or from a decom-position of water actually taking place during the experiment.

Remarks. ..There are instances recorded of a vapour issuingfrom the stomach of dead persons, which took fire on the ap-proach of a candle. We even find accounts in several works ofthe combustion of living human beings, which appears to bespontaneous. Dr. Swediaur related some instances of portersat Warsaw, who having drank abundantly of spirit, fell downin the street with the smoke issuing out of their mouths; andpeople came to their assistance, saying they would take fire; toprevent which they made them drink a great quantity of milk, orused a more singular expedient by causing them to swallow theurine, of the bystanders, immediately on its evacuation.