s an equal volume of olefiant gas would
have done. In both these cases it was the original oxygen and hydrogen
which combined together, the ether and the oil-gas vapour remaining
unaffected, and in both cases the plates retained the power of acting on
fresh oxygen and hydrogen.

[A] Philosophical Transactions, 1825, p.440.

652. Spongy platina was then used in place of the plates, and jets of
hydrogen mingled with the different gases thrown against it in air. The
results were exactly of the same kind, although presented occasionally in a
more imposing form. Thus, mixtures of one volume of olefiant gas or
carbonic oxide with three of hydrogen could not heat the spongy platina
when the experiments were commenced at common temperatures; but a mixture
of equal volumes of nitrogen and hydrogen acted very well, causing
ignition. With carbonic acid the results were still more striking. A
mixture of three volumes of that gas with one of hydrogen caused _ignition_
of the platina, yet that mixture would not continue to burn from the jet
when attempts were made to light it by a taper. A mixture even of _seven_
volumes of carbonic acid and _one_ of hydrogen will thus cause the ignition
of cold spongy platina, and yet, as if to supply a contrast, than which
none can be greater, _it cannot burn at a taper_, but causes the extinction
of the latter. On the other hand, the mixtures of carbonic oxide or
olefiant gas, which can do nothing with the platina, are _inflamed_ by the
taper, burning well.

653. Hydrogen mingled with the vapour of ether or oil-gas liquor causes the
ignition of the spongy platina. The mixture with oil-gas burns with a flame
far brighter than that of the mixture of hydrogen and olefiant gas already
referred to, so that it would appear that the retarding action of the
hydrocarbons is not at all in proportion merely to the quantity of carbon
present.

654. In connexion with these interferences, I must state, that hydrogen
itself, prepared from steam passed over ignited iron, was found when
mingled with oxygen to resist the action of platina. It had stood over
water seven days, and had lost all fetid smell; but a jet of it would not
cause the ignition of spongy platina, commencing at common temperatures;
nor would it combine with oxygen in a tube either under the influence of a
prepared plate or of spongy platina. A mixture of one volume of this gas
with three of pure hydrogen, and the due proportion of oxygen, w