362 Dr. C. Henry's Experiments on the Action of MetaJs 



affinities of carbonic oxide and hydrogen for oxygen was ob- 

 served in their slow combination at atmospheric temperatures. 

 " The oxygen which had united with the carbonic oxide was 

 to that which had combined with the hydrogen as about 5 to 

 1 in volume." 



From the foregoing facts it may be inferred that when 

 either carbonic oxide or hydrogen gas is condensed with oxy- 

 gen on the surface of platina, it is brought within the range 

 of its combining affinity, and unites with oxygen, the latter 

 rapidly, the former with such extreme slowness as to give evi- 

 dence of the production of carbonic acid only after the lapse 

 of a day or two. When the two gases are simultaneously con- 

 densed with oxygen sufficient to saturate only one of them, 

 the stronger affinity of carbonic oxide for oxygen prevails 

 over the weaker affinity of hydrogen for oxygen, and induces 

 the formation of carbonic acid, but so tardily as to exhibit no 

 immediate action, and hence to give occasion to the phae- 

 nomena of interference. The retarding influence of foreign 

 gases may, then, like the non-action of the oxidizable metals, 

 be traced to the operation of a countervailing affinity. 



The insufficiency of most of the hypotheses previously 

 framed to explain this class of phaenomena has been fully ex- 

 posed by Dr. Faraday. There is one, however, which de- 

 serves to be noticed, since, though adopted by some of the most 

 eminent German chemists, it appears to have escaped his ob- 

 servation. Proposed by Dobereiner in Schweigger's Journal, 

 it seems to have reached the Annates de Chimie only through 

 a memoir of Liebig*. Platina in the form of powder is as- 

 serted by Dobereiner to absorb many volumes of the unmingled 

 gases, and especially of pure hydrogen. Thus, 100 grains 

 absorbed 20 cubic inches of hydrogen, or in volume 1 cubic 

 inch of powder absorbed 745 cubic inches of the gas. A 

 small part of this (5 cubic inches) is supposed to have been 

 employed in the formation of water, and the remaining 15 

 cubic inches to have been simply condensed by the powder, 

 by an action resembling, but greatly exceeding in amount, that 

 of charcoal. The heat evolved by this enormous condensa- 

 tion is calculated to be fully adequate to render the metal in- 



• torn. xlii. p. 316. [We cannot at present refer to Schweigger, but 

 the passage in the Annales]u%t cited, relates merely to the black precipi- 

 tate obtained by Mr. E. Davy by heating sulphate of oxide of platinum with 

 alcohol, and not to platinum powder. This, in conjunction with the 

 statement mentioned in our note on the succeeding page, seems to indicate 

 the existence of some error in the history of the subject as stated above. 

 Perhaps Dr. C. Henry will have the goodness to reconcile the apparent 

 contradiction in our next Number. — Euix.] 



