Thallium behaves similarly to lead.  From a nitric acid solution it is thrown down, according to the proportion of free acid, either as sesquioxide only or in small quantities as silvery, metallic leaflets; from alkaline solutions it is deposited as sesquioxide and metal, the latter of a lead-gray color.  Thallium solutions conduct the electric current badly.  Thallium oxide resembles lead peroxide in color; at a strong heat it melts, becomes darker, and is converted into peroxide, in which state it can be weighed.

Silver.—­All solutions of silver salts, except the nitrate, and those containing a very large quantity of free nitric acid or nitrates, deposit electrolytically merely metallic silver.  In the above mentioned exceptional cases there is formed a small quantity of peroxide which adheres to the anode as a blackish-gray deposit.  The greatest quantity of peroxide is obtained on employing a concentrated, strongly acid solution of the nitrate, and a strong current.  If the solution is very dilute we obtain no peroxide, or mere traces which disappear again toward the end of the process.  The peroxide is deposited at first in small, dark, shining octahedral crystals; subsequently, in an amorphous state.  At 110 deg. it evolves oxygen suddenly, and is converted into 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