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Alkaline carbonates are soluble, the other carbonates are not. Nitrates. All nitrates, excepting a few sub-nitrates, are soluble in water.

A solid nitrate, heated with concentrated sulphuric acid, evolves fumes of nitrous acid, sometimes accompanied by red-brown vapors of peroxide of nitrogen.

Otherwise, heat the nitrate with concentrated sulphuric acid, then put in a slip of clean metallic copper, red vapors of peroxide of nitrogen are evolved.

Otherwise, to a solution of a nitrate, add its bulk of concentrated sulphuric acid. When cool, suspend a crystal of protosulphate of iron, (green copperas.) After sometime, a brown ring will appear about the crystal. The liquid in this case must not be stirred or heated.

Phosphates. Generally dissolve in nitric and hydrochloric acids. Sulphuric acid does not give any reaction, but generally decomposes them. With phosphates soluble in water, nitrate of silver gives a lemonyellow phosphate of silver. Is soluble, with difficulty, in acetic acid.

Phosphates. Insoluble in water, are dissolved in nitric acid, then this solution is neutralized by ammonia; to this neutral mixture, the nitrate of silver test gives the above yellow color.

Sesquioxide of Iron. In an alkaline solution of a phosphate, gives an almost white gelatinous precipitate of phosphate of sesquioxide of iron. Insoluble in acetic acid.

Molybdate of Ammonia, added to any phosphate solution, and then nitric or hydrochloric acid added in excess, a yellow color soon appears, and subsequently a yellow precipitate.

This is a very characteristic test.

substance ought to be first dissolved in nitric acid, and then nearly neutralized before adding the molybdate of ammonia.

Sulphates. Nearly all the sulphates are soluble in water. They do not effervesce with acids. This distinguishes them from carbonates. The sulphates of baryta, strontia and lead, are nearly insoluble; that of lime is slightly soluble.

From all the soluble sulphates, nitrate of baryta or chloride of barium, throws down a white precipitate insoluble in nitric acid, which is a characteristic property of the sulphates. In applying this test, the solution ought to be neutral or nearly so. This can be done by adding Magnesia to the solution so as to render it equal to sulphate of magnesia, MgO, SO3.

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BLOW PIPE EXAMINATIONS.

310м. Heat a portion of the substance on charcoal, in the inner flame of the blow pipe.

If potash or soda, the flame is tinged yellow.

If an alkaline earth, (barium, calcium, strontium, magnesium,) it will radiate a white light, and is infusible. Now moisten this infusible mass with nitrate of cobalt and heat again.

If the flame becomes blue, alumina is present.

If green, oxide of zinc.

If pale pink, magnesia; but if silica, it will fuse into a colorless bead, on the addition of carbonate of soda.

If a bead, or colored infusible residue is formed, mix it with carbonate of soda, and heat on charcoal in the inner flame of the blow pipe.

If tin, copper, silver or gold, are present, a bead of the metal will be formed, without any incrustation on the charcoal.

If iron, cobalt or nickel, are present, the metal will be mixed up with the carbonate of soda, giving the bead a gray opaque appearance.

If zinc or antimony, it will give a white deposit around the bead.
If lead, bismuth or cadmium, a yellow or brown deposit.

QUALITATIVE ANALYSES OF METALLIC SUBSTANCES.

310N. Let M equal the mass or substance to be analyzed. We reduce it to a fine powder and boil with hydrochloric acid, so as to reduce it to a chloride, but if we suspect the presence of a metal not soluble by the above, we boil it with aqua regia (= nitro-hydrochloric acid) until it is dissolved; then we evaporate and boil again with dilute hydrochloric acid and evaporate to dryness, and so continue till every trace of nitric acid disappears. We have the metals now reduced to chlorides, which are soluble in distilled water. The solution is now set aside for analysis, which is to be acid, neutral or alkaline, as the nature of the reagent may require.

The solution is acid if it changes blue litmus paper red, and alkaline, if it changes red litmus paper blue, or turmeric paper brown.

Taylor gives nitro-prusside of sodium as a very delicate test for alkali, He "passes a little hydrosulphuric acid into the solution to be examined, and then adds the solution of the nitro-prusside of sodium, which gives a magnificent rose, purple, blue crimson color, according to the strength of the alkaline. This will indeate an alkali in borates, phosphates, carbonates, and in the least oxideable oxides, as lime and magnesia." The metals are divided into groups or classes.

CLASS I. Potash KO, soda NaO, and ammonia NH3. None of these, in an acidified solution, gives a precipitate with hydrosulphuric acid, hydrosulphate of ammonia, or carbonate of soda.

CLASS II. Magnesia, MgO. Lime, CaO. Baryta, BaO. Strontia, SrO. None of these gives a precipitate with hydrosulphuric acid, or hydrosulphate of aminonia.

Carbonate, or phosphate of soda, with either of this class, gives a copious white precipitate insoluble in excess.

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Protoxide of manganese MnO. Per oxide of iron Fe203. In neutral solutions these metals are precipitated by hydrosulphate of ammonia.

In a slightly acid solution, hydrosulphuric acid gives no precipitate excepting with peroxide of iron, with which it gives a yellowish white prec.

CLASS IV. Arsenious acid As03, arsenic acid As05, teroxide of anti mony SbO3, oxide of mercury HgO, peroxide of mercury Hg02, oxide of lead, copper, silver, tin, bismuth, gold and platinum.

All of this class are precipitated from their acid solution by hydrosul

phuric acid. We can thus determine to which of the four classes of metals the substance under examination belongs.

POTASH, in a solution of chloride of potassium.

* Bichloride of platinum, in a neutral or slightly acid solution, gives a fine yellow crystalline prec., KCl. Pt. C12, sligtly soluble in water, but insoluble in alcohol; somewhat soluble in dilute acids. When the solution is dilute, evaporate it with the reagent on a water bath, and then digest the residue with alcohol, when the above yellow crystals will appear.

Tartaric acid. Let the solution be concentrated, then add the reagent, and agitate the mixture with a glass rod for some time, and let it remain, when a white prec, slightly soluble in water, will appear, the prec KO. HO. C8 H4 010.

Blow Pipe flame.

Wash the platinum wire in distilled water, then place a piece of the salt to be examined on the wire, which will give a violet color to the outer flame.

Alcohol flame, having a potash salt in solution, gives the same reaction as the last.

SODA, in a solution of sulphate of soda.

Bichloride of platinum, added as for potassa, then evaporated, will give yellow needle-shaped crystals different from that by potassa. The prec. is readily soluble in water and alcohol.

Antimoniate of potash. Let the solution and the reagent be concentrated, and the solution under examination slightly alkaline or neutral; then apply the reagent, which, if soda is present, will produce a white crystalline prec. of antimoniate of soda.

Blow Pipe. Hold the salt on the platinum wire in the inner or reducing flame, it will impart a golden yellow color to the outer, or oxidizing flame. OXIDE OF AMMONIUM, NH40, in a solution of chloride of ammonium. Bichloride of platinum gives the same reaction as for potassa. If we have a doubt whether it is potassa or ammonia, ignite the precipitate and digest the residue with water, then, if nitrate of silver be added, and gives a precipitate, it shows the presence of potassa. In this case we must take care that all traces of hydrochloric acid are removed.

Heated in a test tube. If the substance be heated in a test tube with some hydrate of lime, or caustic potassa or soda, it will give off the peculiar odor of ammonia, and changes moistened turmeric paper brown and red litmus paper blue. If this does not happen, we say ammonia is absent. BARYTA, BaO, in a solution of chloride of barium.

Sulphuric acid. White prec. in very dilute solution, insoluble in dilute acids.

Sulphate of lime, in solution, gives an immediate prec., requiring 500 times its weight of water to dissolve it.

Oxalate of ammonia. White prec. readily sol. in free acids. This is the same reson as for lime, but it requires a stronger solution of baryta than of lime.

Flame of alcohol, containing baryta, is yellowish, and is different from that of lime, which has a reddish tinge, and strontia, which is carmine. Blow Pipe, in the inner flame, the substance strongly heated on plati

Those marked with an asterisk are the most delicate tests.

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If the sub

num wire, imparts a light green color to the outer flame.
stance be insoluble, first moisten it with dilute hydrochloric acid.
LIME,

CaO, in a solution of chloride of calcium.

Oxalate of ammonia. Let the solution be neutralized with muriate of ammonia; then add the reagent, which will give a copious white prec. of oxalate of lime, soluble in hydrochloric acid, but insoluble in acetic acid.. This detects lime in a highly diluted solution.

Sulphuric acid, dilute. In concentrated solution gives an immediate prec. soluble in much water, which is not the case with barytą.

Blow Pipe. Heated in the inner flame, gives an orange red color to the outer flame. Moisten an insoluble compound with dilute hydrochloric acid before this test.

Burnt with alcohol, the flame will be a reddish tint, but not so red as that given by strontia..

STRONTIA = Sr0.
Sro. In a solution of chloride of strontium.

Oxalate of ammonia, in concentrated solution, a white prec., but not in dilute solution. This distinguishes strontia from lime.

Sulphate of lime. The prec. will be formed after some time even in a concentrated solution. This distinguishes strontia from baryta. (See above.)

Sulphuric acid gives an immediate prec. in a concentrated solution, but only after some time in a dilute one, where the prec. will be minute crystals.

In the flame of alcohol, stir the mixture, and a beautiful carmine color is produced..

Blow Pipe, in the inner flame, an intense carmine red. Moisten the insoluble compound with dilute H. Cl as above for lime and baryta.

NOTE. Sulphuric acid gives, with a weak solution of lime, no precipitate; with chloride of barium, an immediate white p.; with a weak solution of strontia, a prec. after some time. The prec. from baryta and strontia are insol. in nitric acid, but that from lime is sol.

MAGNESIA MgO., in a solution of sulphate of magnesia MgO. SO3. Phosphate of soda, a white, highly crystalline prec. of phosphate of magnesia 2MgO. HO. PO5. In this case the solution must not be very dilute. By boiling the solution and reagent together the prec. is more easily produced.

Phosphate of soda and ammonia. In using this reagent, add ammonia or its carbonate, which makes the prec. less soluble. Agitate with a glass rod, which, if it touches the side of the test tube, will cause the prec. there to appear first. The prec. is crystalline, slightly soluble in water, less in ammonia, but readily in dilute acids; ... the solution must be ammoniacal. Ignite this prec., the ammonia is driven off, and the residue phosphate of magnesia 2MgO. PO5.

Blow Pipe. Moisten the substance with nitrate of cobalt, and heat in the blow-pipe, the compound assumes a pale flesh or rost or.

NOTE. Sulphate of lime gives a prec. with baryta and strontia. Oxalate of ammonia gives a prec. with a very dilute solution of lime, but only with a concentrated solution of magnesia and strontia, and in a much stronger sol. of baryta than lime.

Phosphate of soda, with lime, a gelatinous precipitate.

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Hydrofluosilic acid, in a solution of baryta, gives a white, transparent prec. By evaporating the prec. to dryness, and washing the residue with alcohol, we obtain all of the silico-fluoride of barium undissolved. If the sol. is dilute, the prec. will be after some time.

ALUMIN▲, (A1208,) in a sol. of sulphate of alumina.

Caustic Ammonia, (NII3,) gives a semi-transparent, gelatinous, bulky preć. nearly insol. in excess of the ammonia.

Caustic Potash, (KO,) gives a similar prec. soluble in an excess of the reagent, but if we add chlorate of ammonia to the solution, the alumina is again precipitated.

Hydrosulphate of Ammonia, added to a neutral solution, gives a white prec. of hydrate of alumina, (A1203, HO) and hydrosulphuric acid is liberated.

Phosphate of Soda, white prec., sol. in mineral acids, nearly insol. in acetic acid.

Lime Water, precipitates alumina.

NOTE. Ammonia in excess precipitates alumina, but not magnesia or the other alkaline earths.

CHROMIUM, (Cr203,) in a sol. of sulphate of chrom.

Hydrosulph. Acid, in neither acid or neutral solutions, gives no prec. Hydrosulphate of Ammonia, in a neutral solution, gives a dark green prec. insol. in excess of the reagent.

Caustic Ammonia, if boiled with the solution, will produce the same as the last. If not boiled, a portion of the prec. will re-dissolve, giving the liquid a pink color.

Blow Pipe. Reduce the substance to a sesquioxide of chromium, which will give in the inner flame a yellowish green glass, and in the outer flame a bright emerald green.

Heat with a mixture of nitrate of potash and carbonate of soda; a yellow bead is formed. Dissolve this bead in water acidulated with nitric acid, and add acetate of lead; a bright yellow prec. of chromate of lead is formed.

PEROXIDE OF IRON. In a solution of sulphate of iron, FeO. SO3. The compound is boiled with nitric acid to oxidize the metal, and then evaporated to dryness.

Hydrosulphuric Acid, gives no precipitate.

Sulphide of Ammonium, precipitates the iron completely as a black precipitate of sulphide of iron, FeS, which is insoluble in an excess of the precipitant.

The above precipitate when exposed for some time to the air, becomes brown sesquioxide of iron.

This is the

Ferrocyanide of Potassium, (prussiate of potassæ,) light blue precipitate of KFe3Cfy2. The precipitate is insoluble in dilute acids. most delicate test for iron.

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Sulphocyanide of Potassium. A red solution, but no precipitate.
Tincture of Galls. Bluish black in the most dilute solution.

Caustic Potash. Reddish prec. sol. in excess.

Caustic Ammonia the same, insol. in excess.

Blow Pipe, heated on a platinum wire with borax in the outer flame, gives a brownish red glass, which assumes a dirty green color in the inner or reducing flame.

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