Dr. Wollaston on the Discovery of Palladium. 323 
precipitated by sal ammoniac, or by nitre ; but by prussiate of 
potash it gave a yellow or orange precipitate ; and in the order 
of its affinities it was precipitated by mercury but: not by silver. 
These are the properties by which I originally distinguished 
palladium ; and by the assistance of these properties I obtained 
a sufficient quantity for investigating its nature more fully. 
There were, however, various reasons which induced me to 
relinquish the original process of solution in nitrous acid and 
precipitation by mercury ; for although I found the metal thus 
obtained to be nearly pure, the necessity of agitating the solu- 
tion with the mercury was very tedious, and the waste was also 
considerable ; for in the first place it seemed that nitrous acid 
would not extract all the palladium from any quantity of the 
second metallic precipitate, neither would mercury reduce the 
whole of what was so dissolved. I therefore substituted a 
process dependent on another of its properties. I had observed 
that this metal differed from platina in not being precipitated 
from nitro-muriatic acid by nitre or by other salts containing 
potash ; for although a triple salt is thus formed, this salt is 
extremely soluble, while that of platina on the contrary re- 
quires a large quantity of water for its solution. On that 
account a compound menstruum consisting of nitrate of potash 
dissolved in muriatic acid is unlit for the solution of platina, 
but dissolves palladium nearly as well as common nitro-mu- 
riatic acid in which there is no potash present.* 
In five ounces of muriatic acid diluted with an equal quantity 
of water, I dissolved one ounce of nitre, and formed a solvent 
* I have found that gold may also be dissolved with equal facility by the same 
solvent, and nearly in the same proportion. Ten grains of nitre added to a proper 
quantity of muriatic acid are sufficient for sixteen grains of either gold or palladium. 
Tt 2 
