SCIENTIFIC MEMOIRS. 
VOL. IV.—PART XIII. 
ARTICLE I. 
On the Chemical Reactions produced by Bodies which act only by 
Contact. By Prof. M. E. MirscuHER.icu. 
[From the Annales de Chimie et de Physique, Janv. 1843.] 
For however long a time we leave a mixture of hydrogen and 
oxygen, these gases never combine, even in the presence of such 
bodies as sulphuric acid, potash or lime, which have a great af- 
finity for water, and which apparently should stimulate its forma- 
tion. When, however, metallic platinum is introduced into a 
mixture of these gases, their combination is effected instantane- 
ously on the metallic surface. 
The mixture of these gases may be made in the proportions to 
form water, and at the end of a very short time the hydrogen 
and oxygen are so intimately mixed that each molecule of the 
one must be in the presence of a molecule of the other ; since the, 
molecules of gaseous bodies possess an exceeding great mobility, 
and their cohesion is no obstacle to their combination, as is the 
case with solid and liquid bodies; and since the affinity of hy- 
drogen and of oxygen in water may be supposed to be equal to 
a pressure of several millions of atmospheres; it must surely, 
then, be admitted, that besides the ordinary reasons that are op- 
posed to the chemical combination, there is some other which 
prevents the combination of hydrogen and oxygen by neutral- 
izing their natural affinity. 
Some bodies in solution behave to each other in the same man- 
ner as hydrogen and oxygen do with regard to platinum. A so- 
lution of cane sugar may be left for a very long time without its 
undergoing any change; but if dilute sulphuric acid be added 
VOL. IV. PART XIII. B 
