According to SCHEERER, the oxide of cerium may be entirely freed from the last traces of the oxides of lanthanium and didymium, by dissolving in hydrochloric acid, neutralizing very cautiously with ammonia, adding acetate of ammonia, and then oxalate of the same alkali; the resulting oxalate of the oxide of cerium collected upon a double filter, washed, dried, ignited, and again treated with very weak nitric acid, yields pure oxide of cerium.

The oxide of didymium is the cause of the brown color of the oxide of cerium, and the reddish appearance is due to the oxide of lanthanium. Pure oxide of cerium is citron-yellow; that of lanthanium, white; and that of didymium, brownish-yellow.

MOSANDER found that the compounds of didymium were in many respects analogous to those of manganesium: the oxide is brown, the sulphate of the oxide amethystine: its oxide gives a brown color to oxide of cerium, and a red tinge to the salts of yttria.

In many of the forementioned minerals in which, besides oxide of cerium there are oxides of lanthanium and didymium, and no other colored oxides to any appreciable extent, exempli gratia, in fluoride of cerium, in phosphatic and carbonated combinations, and in Cerite, the presence of the oxides under consideration, is easily detected. In the oxidating flame with borax or microcosmic salt these minerals afford a red or dark-yellow bead, according to the quantity of the assay which may be dissolved in the glass, but the beads with the latter reagent become colorless in the cold, or under the influence of the reducing flame, while the borax bead under the same circumstances becomes streaked or enamelled, according to the amount of silicic acid in the mineral. HERMANN states that he could not detect the least trace of didymium in his researches on Cerite.

L. BONAPARTE had been occupied for some time in the chemical investigation of several metallic valerianates, and especially those of cerium, when he became aware of MOSANDER's discovery of didymium. He had succeeded in finding in a concentrated solution of valerianic acid a most excellent means of separating the binoxide of cerium in a pure state from the binoxide of didymium.

Valerianic acid possesses a singular and unexpected affinity for binoxide of cerium, and occasions an abundant precipitate in a neutral and concentrated solution of the mixed nitrates of the binoxides of didymium and cerium. The yellowish-white precipitate consists entirely of the valerianate of the binoxide of cerium, and to obtain the pure binoxide it only requires a thorough washing and calcination at a strong red heat in contact with the atmosphere. This oxide is of a very pale yellow color, like that described by MOSANDER, who, however, expressly states that he had hitherto not been able to find any absolute means of separation for the oxides of cerium, lanthanium, and didymium.

The oxide of didymium remains dissolved in the acid liquid, from which the valerianate of the binoxide of cerium has been precipitated. A portion of the cerium, however, remains mixed with the didymium, for the valerianates of these two metals are slightly soluble in water, and still more so in acid liquids, especially that of didymium, which is far more soluble in weak acids than that of cerium. It is possible, however, by means of valerianic acid, to obtain the oxide of didymium in a state of purity, although with much more difficulty than that of cerium.

BONAPARTE further states that, to obtain the pure valerianate of the binoxide of cerium from the mixed nitrates of the binoxides of cerium and didymium, it is necessary to throw down this salt by an aqueous and concentrated solution of valerianic acid; if a soluble valerianate were employed, the didymium, which is very slightly soluble in the state of valerianate in neutral solutions, would likewise be precipitated. The easy preparation of the binoxide of cerium in a pure state is owing, therefore, to the great solubility of valerianate of didymium in acid liquids, and to the less solubility of that of the binoxide of cerium under similar circumstances.

In minerals which contain oxides of uranium and iron, titanic acid, et cetera, the presence of oxides of cerium, lanthanium, and didymium are not easily recognized by the Blowpipe. When the least doubt arises, the best way is to have recourse to the humid method, and to treat the oxides thus obtained with the special fluxes.

§ 2. MANGANESE-Mn-Presence of this Metal in the Mineral Kingdom, and in the Scoria from Smelting Works.

Manganese occurs in nature :—

a. As a Sulphide, in Mangan-Blende [Mn S];

b. As an Oxide, alone, as well as in combination with other Metallic Oxides; exempli gratia, per se in Grey Oxide of Manganese [Mn 02]; as a Hydrate, in Black Wad [Ba O, Mn2 03, H O] and [Mn2 O3, H 0 + 2 (Fe2 03, H 0) ],

A sample of the latter, analyzed by WACKENRODER, gave,—

With Oxide of Cobalt and Water, in Black Earthy Cobalt [Co O, Mn2 03 + 3 aq];-according to DÖBEREINER's analysis, the formula is [Co2 O3, Mn2 03 + 3 aq]-and with Sesquioxide of Iron, Protoxide of Iron, and Oxide of Zinc, in Franklinite

Mn O

Fe O

Dodecahedral Iron Ore,― Mn 03]; or, according to Ko

Fe2

BELL, [2 Zn 0, 3 Mn 0 + 5 (Fe 0, Fe2 03)];

c. As a Protoxide, in a Phosphoric Acid combination containing Protoxide of Iron and a small quantity of Lime; exempli gratia, Triplite-Phosphate of Manganese and Iron—[4 Mn O, P 05+ 4 Fe 0, P 03] ;

d. As Protoxide, with Tungstic Acid and Tungstate of Iron, in Wolfram [Mn O, W 03 + 3 (Fe 0, W 03) ] ;

e. As Protoxide, with Tantalic Acid, Protoxide of Iron, Oxide of Tin, Tungstic Acid, and Lime, in various Tantalites;

f. In an oxidized state, in Silicic Acid compounds; per se, in Red Siliciferous Oxide of Manganese [3 Mn O, Si Oo]; further, with Protoxide of Iron, Alumina, and Water, in Umber; with Protoxide of Iron, Protochloride of Iron and Water, et cetera, in Pyrosmalite [Fe Cl3 + Fe2 03, 6 H O] or [4 (3 Fe 0, 2 Si 0o + 3 Mn 0, 2 Si O2)]; with Alumina, Lime, and sometimes Magnesia, in Garnet ;-general formula 3 F Si O + Al2 03,

3 Mg

3 Ca O

3 Mn O

Si O2]; with Protoxide of Iron, Alumina, and Water, in Chloropal; and also as an extremely small ingredient of numerous other Silicates.

Manganese is very seldom met with in the metallic state, in the scoria or recrements from the smelting process. It is generally in combination with oxygen, sulphur, or other metals, or else is taken up by the silicates which mostly compose the slags. Manganese also occurs in Manganglance, Hausmanite, Braunite. Manganite, Psilomelan, Varvicite, Polianite, Pyrolusite, Grovoilite, Huraulite, Eisenapatite, Hetopozite, Triphyline, Tetraphyline, Manganocalcite, Tantalite-from Kimito, Tamela, Finbo, Broddbo, and Bodenmais-Tephroite, Fowlerite, Troostite, Knebelite, Helvine, Karpholite.

Examination for Manganese.

Substances containing no other metals save manganese, give colored glasses with borax and microcosmic salt in the oxidating flame, and can be very readily recognized, when dissolved in the named fluxes on a platinum wire, and the pearl treated in the reducing flame. After oxidation, the glasses appear amethystine, and by reduction colorless. The amethyst tinge is not affected on exposure to the oxidating flame, if a substance at the same time contains other coloring ingredients, but is in the reducing flame. If the presence of manganese is considerable, the pearl must be suddenly removed after reduction, because the color returns if allowed to cool gradually, owing to a higher state of oxidation ensuing.

M

When the quantity of manganese is so inconsiderable that it affords no amethyst color, either with borax or microcosmic salt, in the oxidating flame, a microcosmic glass must be formed, in which a sufficient quantity of the substance under examination has dissolved, and brought in contact with a crystal of nitre, as described with the reagents, page 52; by which means the assay despumates, and the pellicle, on cooling, assumes, in proportion to the quantity of manganese present, an amethystine or slightly rosy appearance. This procedure is not available in compound combinations, in which other metals or metallic oxides that likewise impart a color to the borax or microcosmic glass present themselves; and recourse must be had to soda, which is decidedly the most characteristic reagent for manganese. In a substance containing less than 0.1 per cent. of oxide of manganese, the detection of this metal succeeds very readily in the following manner :-The substance under examination is reduced to an impalpable powder, mixed with from two to three times its volume of carbonate of soda, and the mixture melted in the oxidating flame on platinum foil. The oxide of manganese dissolves in the soda, forming a transparent green mass, which flows round the undissolved portion, and appears distinctly bluish-green on cooling. Should the quantity of manganese be less than 0.1 per cent., this green appearance is not produced with soda alone, but when two parts of this alkali, and one part nitre, are applied, all the manganese is converted into a higher oxide; the soda is colored characteristically green, even by the smallest trace of this ingredient, which color becomes distinct on cooling. A similar method must be employed for the determination of manganese in Rose Quartz. The fine quartz powder, with soda and nitre, is kneaded into a paste with water, placed in the ring of the platinum wire, and melted to a pearl before the oxidating flame. This pearl is, while hot, transparent and colorless; on cooling, opaque; and when cold, slightly, but very distinctly, green.

If the substance consists of metallic sulphides and arsenides, it must be well roasted on charcoal, previous to the treatment on platinum wire, with soda, or soda and nitre.

When manganese forms a constituent of a substance, contain