108	Faraday's Researches
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.
 389.	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 hydro-
carbons is not at all in proportion merely to the quantity of
carbon present.
 390.	In connection 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, was not affected by plates after fifty
hours.    I am inclined to refer the effect to carbonic oxide present
in the gas, but have not had time to verify the suspicion.   The
power of the plates was not destroyed (376, 382).
 391.	Such are the general facts of these remarkable inter-
ferences.    Whether the effect produced by such small quantities
•of certain gases depends upon any direct action which they
may exert upon the particles of oxygen and hydrogen, by
which the latter are rendered less inclined to combine, or
whether it depends upon their modifying the action of the plate
temporarily (for they produce no real change on it), by invest-