326 Dr.W. C. Henry's Experiments on Gaseous Into ferencc 



Since the gaseous products admit of exact analysis only 

 over mercuiy, a fluid through which the plate cannot be 

 passed without destroying the purity of surface essential 

 to its activity, I was induced to employ balls of platina and 

 China clay in the greater number of instances. Such balls, 

 introduced over mercury into mixtures containing from ^ith 

 to ^jth of carbonic oxide, produced no instantaneous action. 

 But in the course of five minutes there was generally a visible 

 diminution of volume, and in the space of two hours the ac- 

 tion was complete. When the carbonic oxide formed a larger 

 element of the mixture, as from |th to g^rd, the action was 

 still longer delayed. With one third there was scarcely any 

 visible decrease of volume during the first hour ; and even 

 on the following day there remained much gaseous matter 

 unconsumed. Thus the residue of a mixture of 'SS cu. in. of 

 carbonic oxide with -70 of hydrogen and oxygen in com- 

 bining proportions (together 1'05), amounted after twenty- 

 four hours' contact with the ball to '82. The proportions 

 were extensively varied between \ and J^ th as limits ; and be- 

 tween these it was observed, that combination to a greater or 

 less amount was in all cases induced by a sufficient duration 

 of contact. Carbonic oxide, it appears then, does not jrrcvent 

 but only retards gaseous union. 



To ascertain the proportions in which the oxygen had been 

 shared by the gases opposed to each other, the residue was 

 washed with limewater or with caustic potassa. In all cases 

 a notable diminution, due to the absorption of carbonic acid, 

 was observed, and from the limewater carbonate of lime was 

 precipitated. The quantity of carbonic acid so formed varied 

 with the varying proportion which the carbonic oxide had 

 borne to the hydrogen of the explosive mixtui'e. When the 

 hydrogen and carbonic oxide vvere present in equal volumes, 

 and the oxygen was sufficient to saturate one of ihem only, 

 I found that the carbonic oxide had appropriated to itself, in 

 one experiment eight times, in another as much as ten times, 

 the volume of oxygen that the hydi'Ogen had taken. When the 

 carbonic oxide was inferior in volume to the hydrogen, less 

 oxygen was expended in the production of carbonic acid, but 

 still considerably more in proportion than had combined with 

 the hydrogen. It is then a general fact, that carbonic acid is 

 generated in all cases in which carbonic oxide suspends the 

 action of platina on mixtures of oxygen and hydrogen. 



The next object of inquiry was to ascertain the action ol 

 platina in its various forms on mixtures of carbonic oxide with 

 oxvgeu only. Dr. Faraday had noticed that at common tem- 

 peratures " a mixture of two volumes carbonic oxide and 



