126 Mr. Chenevix on the Action of 
place is independent of every substance except the metals 
themselves. 
Exper. 9. One of the most delicate tests that I have observed 
in chemistry is recent muriate of tin, which detects the pre- 
sence of the smallest portion of mercury. When a single drop 
of a saturate solution of neutralized nitrate or muriate of 
mercury is put into 500 grains of water, and a few drops of a 
saturate solution of recent muriate of tin are added, the liquor 
becomes a little turbid, and of a smoke-gray colour. If these 
500 grains of liquid be diluted with ten times their weight of 
water, the effect is of course diminished, but still it is per- 
ceptible. I had on a former occasion observed the action of 
recent muriate of tin upon a solution of platina. If a solution 
of recent muriate of tin be poured into a mixed solution of 
platina and mercury, not too concentrated, it can hardly be 
distinguished from a simple solution of platina. But if too 
much mercury be present the excess is acted upon as mercury ; 
and the liquor assumes a darker colour than with platina alone. 
From all these experiments it is evident that mercury can 
act upon platina, and confer upon it the property of being pre- 
cipitated in a metallic state by green sulphate of iron. By 
Experiments 1 and 2, it is proved, 1st, That platina can protect 
a considerable quantity of mercury from the action of nitric 
acid ; and sdly, That mercury can increase the action of nitro- 
muriatic acid upon platina. From Experiments 3, 4, 5, 6, 7, 8, 
it appears that mercury can combine with platina in such a 
manner as not to be separated by the degree of heat necessary 
to fuse the compound, since after the fusion it retains that 
property, which is essentially characteristic of the presence of 
mercury in a solution of platina. The 8th Experiment proves 
