46 On some Chemical Effects produced by Platinum. 



the same properties as platinum after being exposed for some 

 time to the same gases when moist. If the oxidizing powers 

 of platinum should depend upon a film of peroxide of hydro- 

 gen attached to that metal, it is obvious that spongy pla- 

 tinum, freed from its adhering water and placed within com- 

 pletely dry oxygen, could not assume oxidizing properties. 

 Supposing however that spongy platinum acquires oxidizing 

 powers under the circumstances mentioned, we may never- 

 theless imagine that those powers depend upon a film of per- 

 oxide of hydrogen surrounding that metal. De la Rive's and 

 Marignac's experiments have shown that oxygen obtained 

 from fused chlorate of potash, on being exposed to the action 

 of electrical sparks, yields perceptible quantities of ozone. 

 Now, taking that odoriferous substance for a peroxide of hy- 

 drogen, we must admit that even that oxygen, which is consi- 

 dered as absolutely anhydrous, still contains traces of aqueous 

 vapour. Taking for granted the humidity of what is called 

 dry oxygen, we may easily conceive how platinum brought 

 into an anhydrous mixture of oxygen and hydrogen could 

 cause the combustion of the latter. Out of some oxygen and 

 the traces of water still contained in what is considered anhy- 

 drous detonating gas, a film of peroxide of hydrogen would 

 be formed around the spongy platinum ; that peroxide, in the 

 very moment of its being engendered, would oxidize a neigh- 

 bouring portion of free hydrogen. The heat resulting from 

 that oxidation would determine another portion of hydrogen 

 to unite with oxygen. The heat proceeding from that che- 

 mical union would occasion the combustion of an additional 

 portion of hydrogen, and so on until the whole of the detona- 

 ting gas should be consumed. The minute quantity of the 

 peroxide of hydrogen attached to the spongy platinum would 

 act like a small common or electrical spark, which, as we well 

 know, is capable of setting the largest volume of detonating 

 gas on fire. Electrical sparks acting upon a mixture of oxy- 

 gen and hydrogen, exactly in the same way as spongy pla- 

 tinum does, and it being a well-ascertained fact that ozone 

 makes its appearance on causing common electricity to pass 

 through (moist) oxygen, it is possible that electricity and pla- 

 tinum occasion the oxidation of hydrogen, because both of 

 them are able to produce ozone, and that it is to the agency 

 of that odoriferous substance that we are to ascribe the che- 

 mical effect mentioned. That conjecture must become still 

 more plausible, if we take into account the fact that spongy 

 platinum acts in a variety of other cases exactly like ozone. 

 Taking this view of the case, we could not admit that an 

 electrical spark has the power to cause directly the formation 



