278 Proceedings of the Royal Society. 
to hydrogen, carbonic oxide is most disposed to unite with oxygen; 
then olefiant gas, and lastly carburetted hydrogen. By due regu- 
lation 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 ex- 
clusion is attended with some difficulty, and it is generally more 
or less converted into carbonic acid and water, 
The second section of this paper related to the action of finely- 
divided platinum upon gaseous mixtures at 7xcreased temperatures. 
In these experiments the gases mixed with oxygen enough to sa- 
turate them, were severally exposed in small retorts containing a 
platinum sponge, and immersed in a mercurial bath to a tempera- 
ture which was gradually raised till the gases began to act on each 
other. It was thus found that carbonic oxide began to be con- 
verted into carbonic acid at about 300°; olefiant gas was decom- 
posed 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 gas, with an equal volume 
of oxygen, 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 observed that it is most 
remarkable in those which possess the strongest attraction for 
oxygen, 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 respect. 
Dr. Henry concluded this communication by pointing out the 
best methods of analyzing mixtures of the combustible gases in 
unknown proportions, 
An Account of the Organs of Generation of the Mexican Proteus in 
a developed state. By Sir E. Home, Bart., V.P.R.S. 
The specimens described in this paper were taken in the month 
