Properties of Spongy Platina. 321 
ART. LXIV — CHEMICAL AND PHYSICAL PROPERTIES OF SPONGY 
PLATINA. By J. W. Dobereiner. 
Platina obtained by the wet process, which I term ethiops 
of platina, on account of its black color, is distinguished as is 
well known, by its property of transforming alcohol into acetic 
acid, in atmospheric air or in oxygen. 
I for a long time considered this property as arising from 
a dynamic power, peculiar to platina, that is, an action pro- 
duced by mere contact; but ulterior researches, on the manner 
in which this preparation acts with other oxydizable sub- 
stances, have changed my opinion in a great degree. In fact, 
many of these afforded phenomena, which not only indicated, 
but positively demonstrated, that the ethiops of platina was 
able to act as an oxidizing body alone, that is, without the 
contact of air ; that when its action is exhausted, and it is ex- 
posed to the air, it deprives this latter of its oxygen, and that, 
in oxidation or acetification of alcohol, it acts in a precisely 
analogous manner to nitrous gas in the formation of sulphuric 
acid. 
If ethiops of platina be moistened with formic acid, a hiss- 
ing and a slight detonation ensue, whilst the temperature of 
the mass is so greatly increased, that it soon appears dry. If 
to this an additional quantity of the acid be added, the same 
phenomena are again induced. 
If the ethiops be placed in contact with formic acid in a 
graduated glass tube filled with mercury, at the moment they 
touch each other there will be an extrication of a considerable 
quantity of an elastic fluid, which will be found to be carbonic 
acid mixed with 5 to 7 per cent, of azote. 
A comparative examination of this ethiops prepared in dif- 
ferent ways, proved, that equal quantities of each, when placed 
in contact with formic acid, gave rise to very different pro- 
portions of carbonic acid. 
Vol. I.— No. 4. 41 
