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Platina and Mercury upon each other. 
that the action of mercury upon platina is not confined to the 
metallic state ; but that these metals can combine and form an 
insoluble triple salt with an acid which produces a very soluble 
compound with platina alone. The 9th Experiment shows that 
platina can retain in solution a certain quantity of mercury, 
and prevent its reduction by a substance which acts most 
powerfully to that effect, when platina is not present. That 
part of the general position therefore which is the object of 
this Paper is proved, if these experiments, upon being repeated 
by other chemists, shall be found to be accurate. 
One or two of the above experiments seem to be in contra- 
diction to some that I have stated in my Paper upon palladium ; 
for in the present examples platina protects mercury against 
the action of nitric acid ; whereas in palladium the mercury is 
not only acted upon itself, but it conduces to the solution of 
platina in the same acid. I am well aware of this objection ; 
but confining myself to my present object, I shall wave all 
further discussion of it till another opportunity. In the mean 
time, however, it may be laid down as an axiom in chemistry, 
that the strongest affinities are those, which produce in any 
substance the greatest deviation from its usual properties. 
When a button of the alloy of platina and mercury as pre- 
pared by any of the above methods, is dissolved in nitro- 
muriatic acid, and afterwards precipitated by green sulphate of 
iron, the entire quantity of the alloy used is seldom obtained. 
A considerable portion of platina resists the action of green 
sulphate of iron, and remains in solution. This may be looked 
upon as the excess of platina, and can be recovered by a plate 
of iron. Hence it appears that less mercury is fixed, than can 
determine the precipitation of the entire quantity of platina ; 
