216 



tion, which was as carefully closed as possible, but to its vitiation by 

 respiration, and by the absorbent power of the pleura. 



On the Action of finely divided Platinum on Gaseous Mixtures, and its 

 Application to their Analysis. By William Henry, M.D. F.R.S. 

 Read June 17, 1824. {Phil. Trans. 1824, p. 266.] 



In the first section of this paper the author describes the action of 

 finely divided platinum, at common temperatures, on mixtures of hy- 

 drogen and olefiant gas with oxygen ; of hydrogen and carburetted 

 hydrogen with oxygen; of hydrogen and carbonic oxide with oxygen; 

 of hydrogen and cyanogen with oxygen ; of carbonic oxide and car- 

 buretted hydrogen with oxygen ; of hydrogen, carburetted hydrogen 

 and carbonic oxide with oxygen ; and of the same with the addition 

 of olefiant gas. From the experiments detailed under these several 

 heads, it appears that when the compound combustible gases mixed 

 with each other, with hydrogen, and with oxygen, are exposed to 

 balls of platinum sponge, the several gases are not acted upon with 

 equal facility ; but that next to hydrogen, carbonic oxide is most 

 disposed to unite with oxygen, then olefiant gas, and lastly carbu- 

 retted hydrogen. By due regulation of the proportion of hydrogen, 

 the author remarks, that it is possible to change the whole of the 

 carbonic oxide into carbonic acid, without acting on the olefiant gas 

 or carburetted hydrogen ; he observes, however, that with respect to 

 olefiant gas this exclusion is attended with some difficulty, and it is 

 generally more or less converted into carbonic acid and water. 



The second section of this paper relates to the action of finely di- 

 vided platinum upon gaseous mixtures at increased temperatures. In 

 these experiments the gases, mixed with oxygen enough to saturate 

 them, were severally exposed in small retorts containing a platinum 

 sponge, and immersed in a mercurial bath, to a temperature which 

 was gradually raised till the gases began to act on each other. It 

 was thus found that carbonic oxide began to be converted into car- 

 bonic acid at about 300 ; olefiant gas was decomposed at about 

 500 ; carburetted hydrogen at a little above 555 ; and cyanogen 

 appeared to require a red heat. 



Muriatic acid, mixed with half its volume of oxygen, began to be 

 acted upon at 250, and ammoniacal, with an equal volume of oxy- 

 gen, at 380. 



Adverting to the property inherent in certain gases of retarding 

 the action of the platinum, when they are added to explosive mix- 

 tures of oxygen and hydrogen, Dr. Henry observes, that it is most 

 remarkable in those which possess the strongest attraction for oxy- 

 gen ; and that it is probably to the degree of this attraction, rather 

 than any agency arising out of their relations to caloric, that we are 

 to ascribe the various powers which the gases manifest in this re- 

 spect. 



From his experiments on the action of the platinum on mixed 

 gases, at high temperatures, the author was led to the following 



