Platina and Mercury upon each other. ng 
warm, as in the case of silver, these substances are brought 
into contact under the most favourable circumstances. Yet 
even thus the precipitation is slowly and imperfectly formed, 
often not till several hours have elapsed ; and sometimes a 
very great deficiency of weight is observed, between the quan- 
tities used and those recovered directly by this method. If a 
solution of nitrate of mercury be used, the effect is produced 
more rapidly, and the precipitate is more abundant. The pre- 
cipitation of muriate of platina by nitrate of silver, and the 
combination which ensues from it, suggested to me an experi- 
ment which I must state at length, as from the result of it 
consequences are deduced which modify some of the experi- 
ments of my former Paper. 
It occurred to me that a method of uniting platina and 
mercury without the intervention of any other metal, or of any 
substance but the solvents of these metals might be accom- 
plished as in the case of silver and platina. I therefore poured 
a solution of nitrate of mercury, which solution being at the 
minimum of oxidizement, consequently formed an insoluble 
muriate with muriatic acid, into a solution of muriate of platina. 
The result was a triple salt of platina and mercury, which 
when the mercury was completely and totally at the minimum 
of oxidizement was nearly insoluble. To procure it in this 
state it is sufficient to put more metallic mercury into dilute 
nitric acid than the nitric acid can dissolve, and to boil them 
together. This triple salt of platina and mercury shall be pre- 
sently examined. From this it is evident that to produce the 
union of platina and mercury, the latter being at its minimum 
of oxidizement in nitric acid the addition of green sulphate of 
iron is superfluous. 
