1825.] finely divided Platinum on Gaseous Mixtures. 427 



perature below 400'^ Fahrenheit, the carbonic oxide was entirely 

 acidified ; and on washing out the carbonic acid by liquid 

 potash, the carburetted hydrogen was found unaltered, mixed 

 with the redundant oxygen. 



3d. A mixture of 10 measures of olefiant gas, 10 of carburet- 

 ted hydrogen, and 58 of oxygen, being heated in contact with 

 the sponge to 510° Fahrenheit, the olefiant gas was silently 

 but entirely changed into carbonic acid, while the carburetted 

 hydrogen was not at all acted upon. 



4th. By acting with the sponge upon 42 measures of carbu- 

 retted hydrogen, 22 of carbonic oxide, 22 of hydrogen, and 28 

 of oxygen, first at a temperature of 340° Fahrenheit, which was 

 raised gradually to 480°, all the carbonic oxide was changed 

 into carbonic acid, and all the hydrogen into water; but the 

 carburetted hydrogen remained undiminished in quantity, and 

 was found, after removing the carbonic acid, mixed only with 

 the redundant oxygen. In this experiment, the diminution of 

 volume had continued some time before there was any percepti- 

 ble formation of water, the attraction of carbonic oxide for oxy- 

 gen appearing to prevail over that of hydrogen. The same 

 precedency in the formation of carbonic acid is always apparent, 

 when carbonic oxide and hydrogen, mixed even with oxygen 

 enough to saturate both gases, are raised to 350° Fahrenheit. 



By thus carefully regulating the temperature of the mercurial 

 bath, the action of oxygen upon several gases (carbonic oxide, 

 olefiant, and carburetted hydrogen for example) may be made to 

 take place in succession ; and by removing the carbonic acid, 

 formed at each operation, it may be ascertained how much of 

 each of the two first gases has been decomposed. The carbu- 

 retted hydrogen indeed always remains unchanged, and its 

 quantity must be determined by firing it with oxygen by the 

 electric spark. If hydrogen also be present, it is difficult to 

 prevent the olefiant gas from being partially acted upon ; but 

 this is of little consequence, as I have shown that it is easy to 

 remove that gas in the first instance by chlorine.* It may be 

 remarked, that this method of operating on the aeriform com- 

 pounds of charcoal gives more accurate results than rapid com- 

 bustion by the electric spark, being never attended with that 

 precipitation of charcoal, which is often observed when the gases 

 are exploded with oxygen. A regulated temperature, also, 

 effects the analysis of such mixtures much more correctly than 

 the action of the sponge or balls, because in the latter case the 

 heat produced is uncertain ; and though sometimes adequate to 

 the effect, yet there is always a risk that it may exceed, or fall 

 short of that degree, which is required for the successful result 

 of the analytic process. 



• Philosophical Transactions, 1821, p, 147. 



