to metallic silver. It dissolves in
ammonia with a violent escape of nitrogen. In nitric acid it dissolves
without decomposition and with a red color.

The author uses a galvanic current for reducing silver residues,
consisting of sulphocyanide. The salt is mixed with sulphuric acid in
a roomy platinum capsule, and a fine platinum wire gauze is used as
positive electrode.

_Bismuth._--The current resolves bismuth solutions into metal and
bismutic acid. The latter is deposited at the positive pole, and in
thin layers appears of a golden-yellow, but in thick strata is darker,
approaching to red. Its formation is very gradual, and in time it
disappears again, owing to secondary actions of the current. On
ignition it becomes lemon yellow, and transitorily darker, even brown,
and passes into the sexquioxide.

_Nickel and Cobalt._--On the electrolysis of the ammonical solution
the sesquioxide appears at the positive pole. Its formation is
prevented by an excess of ammonia. The author never obtains more than
31/2 per cent. of the quantity of the metal. The sesquioxides dissolve
in ammonia without escape of nitrogen, and are usually anhydrous.

_Manganese._--Manganese is the only metal which is precipitated only
as peroxide. It is deposited at once on closing the circuit, and is at
first brown, then black and shining. Organic acids, ferrous oxide,
chromic oxide, ammonium salts, etc., prevent the formation of peroxide
and the red color produced by permanganic acid. In very dilute
strongly acid nitric solutions there is formed only permanganic acid,
which according to Riche is plainly visible in solutions containing
1/1000000 grm. manganese. On electrolyzing a manganiferous solution of
copper nitrate, red permanganic acid appeared in a stratum floating
above the platinum disk coated with brown peroxide. No manganese
peroxide was deposited. The peroxide adheres firmly to the platinum
when the proportion of free acid is small, not exceeding 3 per cent.,
and the current is not too strong. If the action of the current is
prolonged after the peroxide is thrown down, it falls off in laminae.
According to Riche, in a nitric solution the manganese is deposited as
peroxide, also at the negative pole. This formation is not directly
due to the current, but is a precipitate occasioned by the production
of ammonia by the reduction of nitric acid. To determine the manganese
in peroxide electrolytically precipitated, it is heated to bright