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OXIDE OF COBALT. COO, in a solution of nitrate or chloride of cobalt. Ammonia, when the solution does not contain free acid, or much ammoniacal salt, the metal is partially precipitated as a bluish precipitate, readily soluble in excess of the reagent, giving a reddish brown solution. Sulphide of Ammonium. A black precipitate of sulphide of cobalt, CoS, soluble in nitric acid, but sparingly in hydrochloric acid.

Sesquicarbonate of Ammonia. A pink prec. CoO, CO2 readily soluble in excess, giving a red solution.

Solution of Potassa. Blue prec changing by heat to violet and red. Ferrocyanide of Potassium. A grayish green prec.

Blow Pipe. In both flames with borax, a beautiful blue glass whose color is scarcely affected by other oxides. In this reaction the cobalt must be used in a small quantity.

OXIDE OF NICKEL, NiO in a sol. of sulphate of nickel, NiO, SO3+7HO. Hydrosulphate of Ammonia. Black prec. from neutral solution, slightly sol. in excess of the reagent, if the ammonia is yellow. The prec. is sol. in NO and sparingly in HCl.

Hydrosulphuric Acid in acidified sol., no prec., but in neutral sol., it gives a partial prec.

* Caustic Ammonia. A light green prec. sol. in excess, giving a purplish blue solution. In this case any salt of ammonia must be


Caustic Potash. Apple green prec. insol. in excess.


Ferrocyanide of Potassium, greenish white prec. Cyanide of potassium, yellowish green prec. sol. in excess, forming a dull yellow sol. this last sol., SO3 precipitates the nickel.

Blow Pipe. Any compound of nickel with carbonate of soda or borax in the inner flame, is reduced to the metallic state, forming a dusky gray or brown beads. In the outer flame the bead is violet while hot, becoming brown or yellow on cooling.

Oxide of MANGANESE = MnO in a solution of sulphate of manganese MnO, SO3 + 7HO.

* Hydrosulphate of Ammonia in neutral sol. gives a bright flesh colored gelatinous prec. becoming dark on exposure to the air. It is insoluble in excess of the reagent, but sol. in HCl and NO5.

* Caustic Ammonia, if free from muriate of ammonia, gives a white or pale flesh colored — MnO, HO, becomes brown in air.

* Caustic Potash, the same as the last, but muriate of ammonia does not entirely prevent the precipitate.

Carbonate of Potash, or Ammonia, white prec. which does not darken so readily as the above. It is slightly soluble in chloride of ammonium. Blow Pipe. Mix the substance with carbonate of soda and a little nitrate or potash, and heat in the outer flame; it will give a green color, and produce manganate of soda, which will color water green.

If the substance is heated with borax in the outer flame, it will produce a bead of a purple color; this if heated in the inner flame will cause the color to disappear.

Oxide of Zinc, ZnO in a solution of sulphate of zinc, Zn, SO +7HO. * Hydrosulphate of Ammonia, in neutral or alkaline solution, gives a copious white curdy prec. if the zinc is pure. If iron is present it will be colored in proportion to the iron present in the sol.

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Hydrosulphuric Acid in acid sol. no prec.

Caustic Ammonia, or Potash, a white gelatinous prec. sqlable in excess. From either solution in excess, hyd. sulph. acid (HS) throws down the white prec. of sulphide of zinc.

Corbonate of Potash, when no other salt of potash is present, gives a white prec. 3 (ZnO, HO)+2 (ZnO, CO2) insol. in excess of the reagent. Blow Pipe, moistened with nitrate of cobalt and heated in the outer flame, gives a pale green color which is a delicate test to distinguish it from manganese, alumina and cobalt.

ARSENIC ACID As05. Boil the compound with HCl, and at the boiling point, add nitric acid as long as red flames of nitrous vapor appear, then evaporate slowly so as not to redden the powder, and expel the acid; then dissolve in distilled water for examination. HS, added to the above sol. slightly acidified with HCl, gives no immediate prec., but if allowed to stand for some time, or if heated to boiling point, a yellow prec. is obtained. Apply the gas several times, always heating to boiling point each time.

Hyd. Sulph. of Ammonia, as in the above solution, but a little more acid gives the same prec. but of a lighter color.

Ammonia nitrate of Silver.

In a neutral solution as first made, add nitrate of silver which gives but a faint cloudy appearance; now add ammonia drop by drop till it gives a yellow prec. of arsenite of silver, which is very soluble in alkali.

NOTE. The same prec. is obtained from the presence of phosphate of soda.

Reinschs' test, in a solution acidified by adding a few drops of hydrochloric acid is a very delicate test, and considered nearly as delicate as Marsh's.

Boil with the acidified liquid in a test tube, a clean strip of copper foil; the arsenic will be prec. on the copper as a metallic deposit. Antimony, bismuth, mercury and silver, give the same reduction as arsenic.

In order to determine which is present, take out the copper foil and dry it between folds of filtering paper, or before a gentle heat; place it in a dry test tube and apply heat; the arsenic being volatile, will be deposited in the upper end of the tube as a crystalline deposit, using but gentle heat. If it were antimony it would not be volatile, and would be deposited as a white sublimate, insol. in water, amorphous, and requiring more heat than arsenic. If it were mercury, it would be in small metallic globules.

Marsh's test, is dangerous, excepting in the hands of an experienced chemist. Those who wish to apply it, will find the method of using it in Sir Robert Kane's Chemistry, or in those of Graham, Fowne, Bowman, and others.

TEROXIDE OF ANTIMONY = SbO3, in a solution of chloride of antimony SbCl3. This solution is made by dissolving the gray ore, or bisulphide of antimony in hydrochloric acid; the solution then diluted with water, acidified with HCl, is examined.

Hydrosulphuric Acid, gives an orange red prec. of BbS8, insol. in cold dilute acids, soluble in potassa and sulphide of ammonia.

Hydrosulphate of Ammonia. Add the reagent in small quantities; it will give an orange prec. of Sb§3, soluble in excess.

Caustic Ammonia, or Potassa. prec. of teroxide of antimony

Add slowly, and it will give a white
SbO3, soluble in excess.

Water in excess. A white prec. which crystallises after some time, and is sol. in tartaric acid.


The same reaction is had with bismuth, but the prec. is not soluble in tartaric acid.

A piece of zinc, in a dilute solution made with aqua regia, precipitates both antimony and tin.

A piece of tin, in the above sol., prec. the antimony.

Teroxide of BISMUTH, in a solution of nitrate of teroxide of bismuth Bi03, 3N05.

Hyd. Sulph. Acid.

A black prec. insol. in cold dilute acids, but sol.

in hot dilute nitric acid. Chromate, or Bichromate of Potash, yellow prec. very sol. in dilute nitric


Water in excess, added to a solution of sesquichloride of bismuth, slightly acidified with hydrochloric acid, produces a white prec. insol. in tartaric acid, which distinguishes it from antimony.

Heat a salt of Bismuth. It turns yellow, but on cooling off, becomes again colorless.

Blow Pipe. In the inner flame with carbonate of soda, it forms small metallic globules, easily broken.

Blow Pipe. In the outer flame with borax, gives a yellowish bead, becoming nearly colorless when cool.

OXIDE OF TIN SnO, in a sol. of chloride of tin, SnCl.

Hydrosulphuric Acid, dark brown prec. in neutral or acid solutions. Insol. in cold dilute acids. If the prec. is boiled with nitric acid, it is converted into the insoluble binoxide of tin.

Hydrosulphate of Ammonia, brown prec. sol. in excess if the reagent is


Chloride of Mercury. First a white prec. then a gray prec. of metallic mercury, even in very dilute solution and in the presence of much HCl. Caustic Ammonia, white bulky prec. insol. in excess.

Caustic Potash, do.

Terchloride of Gold

SnOHO, sol. in excess.

(AuC13) very dilute. In dilute solutions, gives a dark purple prec. known as the purple of Cassius. If this mixture is now heated, it is resolved into metallic gold and binoxide of tin.

PEROXIDE OF TIN Sn02, in a sol. of bichloride of tin SnCl2. Hyd. Sulph. Acid, bright yellow prec. insol. in dilute. SO3, or HCl, made insoluble by boiling with NC5, soluble in HCl added to a litte NO5. Sol. in alkalies.

Caustic Potassa, or Ammonia, white bulky prec. sol. in excess, especially with potassa. The prec. with ammonia is SnO2, HO, and with potassa = KO, 8nQ2.

Blow Pipe. In the outer flame with borax, it will give a colorless bead, but if there is much tin, the bead will be opaque.

A piece of clean zinc, in a sol. of perchloride of tin, will precipitate the tin in the metallic state in beautiful feathery crystals; which under the microscope appear as brilliant crystalline tufts.

HgO, in a solution of bichloride of mercury,

OXIDE OF MERCURY (corrosive sublimate) = HgC12.

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Hydrosulphuric Acid, added slowly, gives a white or yellow prec. If added in excess, it gives a black prec. of HgS, insol. in dilute SO3, HCl or NO5. It is soluble in aqua regia with the aid of heat. If the precipitate be dried and heated in a test tube, metallic mercury is produced.

Chloride of Tin, add slowly, a white prec. of Hg2C1 subchloride of mercury will appear, this prec. becomes gray with an excess of the reagent. If we boil this precipitate in its solution, the mercury is reduced to the metallic state.

* Iodide of Potassium, add drop by drop, gives a beautiful red prec. soluble in an excess of either the solution or reagent.

Heat a strip of copper, the mercury will be deposited on it which when rubbed will appear like silver. If the strip be heated in a test tube, the mercury will appear in minute globules in the cool part of the tube.

OXIDE OF LEAD PbO, in a solution of nitrate of lead, PbO, NO5, made by dissolving the substance in nitric acid, and allowing it to crystallise. We may also use a solution of acetate of lead. Acetate of lead is formed by dissolving oxide of lead in an excess of acetic acid, then evaporate to dryness, the salt is acetate, or sugar of lead.

The following reactions take place with nitrate of lead:

Hydrosulphuric acid, in neutral or slightly acid solution, gives a black prec. of sulphide of lead PbS, but if boiled with nitric acid, it

becomes PbO + SO3.

Caustic Ammonia, a white prec. insol. in excess. Other ammoniacal salts must not be present.

Dilute, SO3, a white heavy prec. nearly insol. in acids, but soluble in potassa. Now collect the prec. and moisten it with a little hydrosulphate of ammonia, it will become black. This distinguishes lead from baryta and strontia, which are insoluble.

Prec. = PbO, CO2.

Carbonate of Potassa, white prec. insol. in excess. Iodide of Potassium, beautiful yellow prec. If this is boiled with water and allowed to cool, beautiful yellow scales are formed.

Chromate of Potassa, fine yellow prec. insol. in dilute acids, but sol. in potassa.

Hydrochloric Acid, a white prec. Boil the solution and let it cool, then needle-shaped crystals will be formed.

OXIDE OF SILVER, AgO, in a solution of nitrate of silver.

Hydrochloric Acid, or any soluble chloride, a white curdy prec. of chloride of silver, insol. in water and nitric acid, sol. in ammonia. This becomes violet on exposure to light, and is sparingly sol. in HCl.

Common Table Salt, gives the same prec.

Hyd. Sulph. Acid, and Hyd. Sulphate of Ammonia, gives a black prec. insol. in dilute acids, but sol. in boiling nitric acid.

Caustic Ammonia, brown prec. sol. in excess.

Caustic Potassa, brown prec. insol. in excess.

Phosphate of Soda, a pale yellow prec. sol. in NO5 and ammonia.

Chromate of Potassa, dark crimson prec.

NOTE. With lead, the prec. would be yellow.

Slip of clean copper, iron or zinc, suspended in the liquid, precipitates the silver in the metallic state.

NOTE. Silver is precipitated by other metals more electro-negative, such as tin, lead, manganese, mercury, bismuth, antimony, and arsenic.

OXIDE OF COPPER. CuO, in a solution of sulphate of copper CuO, SO3 + 5HO.

Hyd. Sulph. Acid, in a neutral, acid or alkaline solution, gives a black prec= CuS, insol. in dilute SO3, or HCl, but sol. in moderately dilute nitric acid. Insol. in excess of the reagent.

Hyd. Sulphate of Ammonia. The same as the last, excepting that the reagent in excess dissolves the prec.

Caustic Ammonia, added slowly, precipitates any iron as a greenish or red brown mud, and the supernatant liquid is of a fine blue color. With nickel, ammonia gives a blue but of a pale sapphire color, whilst that of copper gives a deep ultramarine.

Caustic Potassa, blue prec. insol. in excess. If the potassa be added in excess and then boiled, the prec. will be black oxide of copper = CuO. Ferrocyanide of Potassium Prussiate of Potassa, gives a chocolate colored prec. = Cu2, FeCy3, insoluble in dilute acids. This a very delicate test. The prec. is soluble in ammonia. Potassa decomposes it. Before adding this test, acidify the solution with acetic acid or acetate of potassa.

If but a small quantity of copper is present, no prec. will be produced, but the solution will have a pink color.

Iron or Steel perfectly cleansed in a neutral sol. or one slightly acidified with SO3, will become coated with metallic copper, thus enabling us to detect a minute quantity of copper, which is sometimes entirely precipitated from its solution. This detects 1 of copper in 180,000 of solution. Blow Pipe. In the outer flame with borax while hot, the copper salt is green, but becomes blue on cooling."

TEROXIDE OF GOLD = Au03 in a solution of terchloride of gold. Hydrosulphuric acid, black prec. of tersulphide of gold = AuSs, insol. in mineral acids, but sol. in aqua regia.

Sulphate of Iron, bluish black prec. becomes yellow when burnished. Oxalic acid, if boiled, a prec. of a purple powder, which will afterwards cohere in yellow flakes of metallic gold when burnished.

Chloride of Tin, with a little bichloride of tin, gives a purple tint, whose color varies with the quantity of gold in the solution, and is insol. in dilute acids. In using this test, first add the golden solution to the chloride of tin, and then add the solution of bichloride of tin, drop by drop. If only a small quantity of gold is present, the solution will have but a pink tinge.

Tin-iron Solution. This reagent is made by adding sesquichloride of iron to chloride of tin, till a permanent yellow is formed.

Pour the golden solution, much diluted in a beaker, and set it on white paper. Now dilute the tin-iron reagent, and dip a glass rod into it, which remove and put into the gold solution, when, if a trace of gold is present, a purple or bluish streak will be in the track of the rod. This may be used in acid solutions.

BINOXIDE OF PLATINUM = Pt02, in a solution of bichloride of platinum. Hyd. Sulphuric Acid, black prec. when boiled. Insol. in dilute acids. Chloride of Ammonium. After several hours, a yellow crystalline prec. s lightly sol. in water, but insol. in alcohol.

Chloride of Tin, in the presence of hydrochloric acid, is a dark brown olor; but if the solution is dilute, the color is yellow.

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