424 Dr. Henry on the Action of [June, 



5thly. Muriatic acid gas, mixed with half its volume of oxy- 

 gen, began to be acted upon at 250° Fahr. Water was evidently 

 formed ; and the disengaged chlorine, acting upon the mercurial 

 vapour in the tube, formed calomel, which was condensed, and 

 coated its inner surface. 



6thly. Ammoniacal gas, mixed with an equal volume of oxy- 

 gen, showed a commencement ofdecompositionat380° Fahren- 

 heit. Water was also in this case distinctly generated ; and at 

 the close of the experiment, nothing remained in the tube but 

 nitrogeir and the redundant oxygen. 



I proceeded, in the next place, to examine the agency of 

 finely divided platinum at high temperatures, on those mixtures 

 of gases, which are either not decomposed, or are slowly decom- 

 posed, at the temperature of the atmosphere. 



When carbonic oxide and hydrogen gases, in equal volumes, 

 mixed with oxygen sufficient to saturate only one of them, were 

 placed in contact with the sponge, and gradually heated in a 

 mercurial bath, the mixture ceased to expand between 300° and 

 310° Fahrenheit, and soon began to diminish in volume. On 

 raising the temperature to 340°, and keeping it some time at that 

 point, no further diminution was at length perceptible. From 

 the quantity of carbonic acid, remaining at the close of the 

 experiment, it appeared that four-fifths of the oxygen had united 

 with the carbonic oxide, and only one-fifth with the hydrogen. 

 When four volumes of hydrogen, two of carbonic oxide, and one 

 of oxygen, were similarly treated, the hydrogen, notwithstanding 

 its greater proportional volume, was still found to have taken 

 only one-fifth of the oxygen, while four-fifths had combined with 

 the carbonic oxide. These facts show that at temperatures be- 

 tween 300° and 340° Fahrenheit, the affinity of carbonic oxide 

 for oxygen is decidedly superior to that of hydrogen ; as, from 

 the experiments before described, appears to be the case also at 

 common temperatures. 



But a similar distribution of oxygen between carbonic oxide 

 and hydrogen does not take place when those three gases are 

 fired together by the electric spark. This will appear from the 

 following table, in which the first three columns show the qtian- 

 tities of gases that were fired, and the last two, the quantities of 

 oxygen that were found to have united with the carbonic oxide 

 and with the hydrogen. 



Before firing. After firing. 



Measure of Pleasure of Measure of Oxygen to Oxygen to 



carb. oxide, hydrogen. oxygen. carb. oxide, hydrogen. 



Exp. 1 .... 40 .... 40 20 6 14 



2 .... 40 .... 20 .... 20 12 ... . 8 



3 .... 20 .... 40 .... 20 5 .... 15 



When equal volumes of carbonic oxide and hydrogen gases, 



