651.  A little vapour of ether being mixed with the oxygen and hydrogen retarded the action of the plate, but did not prevent it altogether.  A little of the vapour of the condensed oil-gas liquor[A] retarded the action still more, but not nearly so much as 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, 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 (640. 646.).