2. H2SO produces a white precipitate of SrSO4, which is much less insoluble in H2O than BaSO4, and it therefore precipitates from dilute solutions only on standing or warming. SrSO, is slightly soluble in HCl. 3. CaSO4 produces, after standing some time, a white precipitate of SrSO.

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4. H2SiF does not precipitate strontium solutions. 5. C2(NH4)2O4 produces a white precipitate of C2SO, soluble in HCl and in HNO3, also to a slight extent in NH4Cl, but very sparingly in C2H4O2.

6. K2CrO4 produces, only in concentrated solutions, a yellow precipitate of SrCrO4, soluble in C2H4O2.

7. Heated in the lamp flame a crimson coloration is produced, especially on moistening the salt with HCl.

87. CALCIUM. Ca, c.w. 40.

1. (NH4)2CO3 or K2CO3 produces a white precipitate of CaCO3, which becomes crystalline on heating.

2. H2SO4 precipitates from strong solutions of calcium salts CaSO4, as a white precipitate, which dissolves in a large excess of water, and also in acids. 3. CaSO4 produces no precipitate.

4. H2SiF produces no precipitate.

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5. Ca(NH4)204 produces, even in dilute solutions, a white precipitate of C2CaO, soluble in HCl or HNO3, but insoluble in C2H2O or in C2H2O2

6. Heated in the lamp flame, a dull red coloration is produced, especially on moistening the salt with HCl. This reaction is imperceptible in presence of Ba or Sr salts.

88.-CALCIUM GROUP (IV.).

Separation of Barium,

Heat filtrate from iron group, add to the hot solution NH4Cl and and add CaSO4 solution. An immediate precipitate indicates Barium ; solution. (Test another portion with Sr SO4 for Ba.) To another portion of Neutralize filtrate with (NH4)HO, and add C2(NH4)2O4. An immediate

G.

Strontium, and Calcium.

(NH4)2CO3, and filter. Wash precipitate with hot H2O, dissolve in HCl, a precipitate after some time indicates Strontium, or a dilute Barium the solution in HCl add H2SO4, and boil to remove Ba and Sr. Filter. precipitate indicates Calcium.

STRONTIUM.

Ca PRESENT.

III. Ba AND Ca PRESENT.

precipitate with H2SO4. Add H2SO4 to the HCl solution (diluted to prevent precipitation of Calcium), and filter.

wash well.

Reactions of the Metals of the Potassium Group.

89. Metals whose solutions are unprecipitated by the preceding group reagents, but which have no common precipitant, and are therefore recognized by individual tests.

Magnesium, Potassium, Ammonium, Sodium. MAGNESIUM. Mg, c.w. 24.

1. Na,HPO produces, in presence of (NH4)HO and NHCl, a crystalline white precipitate of MgNH,PO From dilute solutions the precipitation is slow, but may be hastened by stirring with a glass rod. The precipitate is soluble in dilute mineral acids and in C2H402 but is almost insoluble in dilute solution of (NH1)HO.

2. (NH4)HO in neutral solutions produces a partial precipitation of the hydrate Mg(HO), but gives no precipitate in presence of NH4Cl, in which the hydrate is readily soluble.

3. H2SO4, H2SiF, and C(NH4)2O, yield no precipitates.

4. Heated on charcoal in the blow-pipe flame, then moistened with CoCl, and re-heated, a pink mass is obtained.

90. POTASSIUM. K, c.w. 39'I.

1. PtCl produces a crystalline yellow precipitate of 2 KCl+PtCl, except in dilute solutions, which are not precipitated. The precipitation is promoted by stirring, or by addition of alcohol.

2 Tartaric acid precipitates white crystalline hydro

gen potassium tartrate from strong and neutral solutions. The precipitation is promoted by stirring.

3. H.SiF produces a white gelatinous precipitate of K2SiF6.

4. Heated on platinum wire in the non-luminous flame, a violet coloration is produced, which when viewed through a piece of blue glass appears reddish violet.

91. AMMONIUM. NH4, c.w. 18.

1. PtCl produces a crystalline yellow precipitate of 2 NH4Cl +PtCl4, except in dilute solutions, which are not precipitated. The precipitate is insoluble in alcohol and ether, and when ignited leaves a residue of spongy platinum.

2. Tartaric acid produces, in strong solutions, a white precipitate of hydrogen ammonium tartrate, similar in appearance to the corresponding potassium salt.

3. Nessler's solution, added to ainmonia or its salts, produces a yellow coloration, or, if the ammonia compound be present in large quantity, a brown precipitate.

4. NaHo or KHO solution when warmed with ammonia salts decomposes them, and NH, is evolved, which is recognized by its pungent odour, by its turning red litmus paper blue, and by its. forming white fumes with a strong solution of any volatile acid, e.g. HCl.

5. Heated on platinum foil, all compounds of ammonia volatilize completely.

92. SODIUM. Na, c.w. 23.

The soda salts are almost without exception soluble in water, so that the flame test alone serves to distinguish the salts of this metal.