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4. C,H,O, precipitates the oxalate, insoluble in excess, but soluble in HCl.

167. DIDYMIUM. D, c.w. 95.

1. (NH4)HO produces a precipitate of a basicsalt, insoluble excess of the reagent, but sparingly soluble in NH CI.

2. KHO precipitates the hydrate (white), which does not alter on exposure to air.

3. (NH),CO, produces a white precipitate, insoluble in excess of the reagent, but soluble in NH_CI.

4. C,H,O4 produces an almost complete precipitation of the oxalate, soluble in hot HCl.

5. Fused with microcosmic salt in the reducing flame, a reddish violet bead is obtained.

6. Fused with carbonate of soda in the oxidizing flame, greyish white beads are obtained.

168. TITANIUM. Ti, c.w. 50.

1. (NH4)HO or (NH4)2S precipitates H,TiO3 (titanic acid), insoluble in excess of either reagent.

2. KHO also precipitates H,TiO3, insoluble in

excess.

3. BaCO3 produces the same precipitate.

4. Na S202 when boiled with titanium solutions precipitates them completely.

5. Zn produces, first a blue coloration, then a blue precipitate, which ultimately becomes white.

6. Fused with FeSO4 and microcosmic salt in the reducing flame, a bright red bead is obtained.

Reactions of the Rare Metals precipitated as

Sulphides on adding HCI to the filtrate from the Iron Group.

169. VANADIUM. V, c.w. 513.

1. HS produces no precipitate in acid solutions, but a blue coloration by reducing to a lower oxide.

2. (NH), produces in a solution containing H,SO a brown precipitate of the sulphide, soluble in excess of the reagent.

3. NH4Cl in solutions of alkaline vanadates, precipitates the metal completely as ammonium metavanadate (white). This precipitate loses ammonia on heating, and leaves a residue of V,05.

4. K Fe(CN), produces, in acid solutions, a green precipitate, not dissolved by acids.

5. SO2, or oxalic acid, reduces acid solutions of V20, to a lower oxide of vanadium, of a bright blue colour.

6. Zn, added to a solution of V,0, in H2SO4 (diluted with H,0), produces a series of changes in colour, and ultimately a violet solution is obtained, which rapidly becomes brown in air by oxidation.

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Reactions of the Rare Metals found in Potassir me

Group.

170. LITHIUM. Li, c.w. 7.
1. Pt.Cl4 produces no precipitate.

2. Na,HPO, produces, on boiling the solution, a white precipitate of 2 LigP04 + H2O. The precipitate

is soluble in HCl, and is not re-precipitated by (NH)HO unless the solution be boiled.

3. Lithium compounds tinge the lamp flame bright crimson.

171. CÆSIUM. Cæ, c.w. 133.

1. PtCl, produces a crystalline light yellow precipitate of 2 (CæCl) + PtClą, insoluble in boiling water. (The corresponding potassium salt is dissolved by repeated treatment with boiling water.)

2. Tartaric acid produces a precipitate of the acid tartrate of cæsium, more soluble in water than the corresponding compound of rubidium.

3. Volatile cæsium salts colour the flame violet.

172. RUBIDIUM. Rb, c.w. 854.

1. PtCl, produces a crystalline light yellow precipitate of 2 (RbCI) + PtClą, insoluble in boiling water.

2. Tartaric acid produces a precipitate of the acid tartrate of rubidium, which is much more insoluble in water than the corresponding cæsium compound.

3. Volatile salts of rubidium colour the flame violet.

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APPENDIX

TABLE OF THE ELEMENTS, WITH THEIR

SYMBOLS AND COMBINING WEIGHTS.

Element

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Aluminium Antimony Arsenic. Barium Beryllium Bismuth Boron Bromine Cadmium Cæsium Calcium Carbon. Cerium. Chlorine Chromium Cobalt Copper Didymium Erbium

Symbol.

Al
Sb
As
Ba
Be
Bi
B
Br
cd .
Cs
Ca
C
Ce
CI
Cr.
Co.
Cu
D
E

133 40

12

92 35°5 52-2 587 63.5 95 112:6

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