44. If as much PbaO^ (red lead) as can be held on the
point of a pen-knife is added to a solution of the manganous
ion and if the mixture is then strongly acidified with nitric acid,
boiled and allowed to settle, the liquid above has a red color
due to the formation of the permanganate ion. The presence

V|-of hydrochloric acid or chlorin compounds interferes with,
or prevents, the reaction.
2Mn+2SO/' + 26H'-hsPb30,=2H* + 2MnO/ + i3Pb

4-2PbSO,+i2H30, or

2MnS0,+ sPbjO.-f- 26HN03= 2HMnO, + isPbCNO,)^

+ 2PbSO,+ i2H30.
45. Solid compounds of manganese when mixed with
several times their weight of dry sodium_carbonate-and pqj;as-
sium nitrate and fused on the^platinum foil become converted
to green sodium manganate, NajMnO^, the color of which is
best seen while it is melted.
Mn(OH)2 + Na2C03+2KN03=Na3MnO, +2KN0a

+H2O + CO,.
X



METALS (cations) 4I

If too much of the manganese compound is used the mass may
be black. In the cold it dissolves in water to a green solution.
This is decomposed by boiling the liquid, the manganese being
precipitated as an oxid. The green solution is gradually
changed to a pink through exposure to the air, the manganate
ion being converted to a permanganate ion, MnO^'.
Iron, Fe.
The metal is soluble in hydrochloric, sulphuric, and nitric
acids. There are two series of compounds, the ferrous and the
ferric. The former are, for the most part, colorless or greenish
and unite with oxygen when brought in contact with oxidizing
agents, or even when exposed to the air, especially in the pres-
ence of water. They are thus converted into ferric compounds
which are usually yellowish to reddish-brown.
Ferrous Ion (Fe).
For the reactions use a 2-per-cent. solution of FeSO^.
