202 PROOFS OF THE PROPERTIES OF HIDROGEN GAS

Experiment V.

Hidrogen gas is unfit for respiration.

Take a bell-glass ground at the top; having filled it with hi-drogen gas put a bird or any other animal into it, and cover itwith a ground-flat piece of glass to prevent the fluid from escap-ing. The animal confined in the gas will be thrown into violentconvulsions and soon expire, but merely on account of at-mospheric air being excluded, for the hidrogen gas has sufferedno alteration.

Experiment VI.

Hidrogen gas is only inflammable in contact with atmosphericair , or oxigen gas.

Fill a narrow-mouthed phial with hidrogen gas, and take itfrom the pneumatic trough by placing the thumb on the mouththereof to prevent the gas from escaping. If a lighted taper beapplied to the mouth of the bottle the gas will take fire and burnwith a lambent flame. The gas will only burn in contact withthe atmospheric air; the flame will descend gradually till all thegas is consumed; but if the taper be immersed in it, it becomesextinguished as we have seen before, experiment III.

If the hidrogen gas be pure the flame is of a blue colour ; butif the gas holds any substance in solution, which is generally thecase, the flame is tinged of different colours according to thesubstance. It is most usually reddish because the gas holds insolution a little charcoal.

Experiment VII.

The philosophical candle which cannot le easily llou n out.

Fill with hidrogen gas a bell-glass furnished with a capillaryrube; compress the gas by making the bell descend below the