fROFERTIES OF HIDROGEN GAS.

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HIUDMOGEN gas.

PART XVI.

SECT. I.

PROPERTIES OF HIDROGEN GAS.

HIS gas, which was formerly called inflammable air, wasdiscovered by Mr. Cavendish, in the year 1768, though it hadbeen noticed long before by the ancients. The famous philoso-phical candle attests the antiquity of this discovery.

Hidrcgen gas, like oxigen gas, is a triple compound, consist-ing of the ponderable base of hidrogen, (page 138 ) caloric, andlight. It possesses all the mechanical properties of atmosphericair. It is the lightest substance whose weight we are able toestimate : when in its purest state, and free from moisture, it isabout thirteen times lighter than atmospheric air. It is not fit-ted for respiration; animals, when obliged to breathe in it, diealmost instantaneously. It is decomposed by living vegetables,and its basis becomes one of tire constituents of oil, resin, See.It is inflammable, and burns rapidly when kindled, in contactwith atmospheric air or oxigen gas, by means of the electricspark, or by an inflamed body; and burns when pure with ablue lambent flame ; but all burning substances are immediately

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