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solved, at the moment of its formation, into hydrofluate of strychnine and silicic anhydride (Si, 03).

The other special reagents of the present and two preceding groups are

TABLE OF

Al, Cr, 0, Fe (see page 109) (see page 113) (see page 117) (see page 120)

REACTIONS.

Cyanide ......

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Chromate ....... Hydrate. Sulphide .... Carbonate ....... Oxalate Ferrocyanide... Ferricyanide ... Phosphate ......

blue-green
pale green

s reddish
| brown)
yellow-

brown greenish white )

black S greenish l white

yellow pale blue deep blue į greenish 1

white )

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white

green

BLOWPIPE REACTIONS.

(Incandescent The borax- The borax- | The boraxresidue, which, bead is green bead is yellow bead is red

if moistened in the inner, in the oxidiz- dish-brown with CONO, and emerald. ing, green in in the oxidiz

and again green in the the reducing ing flame, and heated, be oxidizing flame. | bottle-green comes blue. flame.

in the reducing flame.

NOTE. -* means that the precipitate formed by the reagent

* means that a precipitate occurs, not of the salt

not known to give any characteristic reactions with solutions of strychnine salts.

Strychnine is usually detected by its reaction with chromic acid.

REACTIONS.

Ni

Fe, Mn Co (see page 125) (see page 129) (see page 132) (see page 136) (see page 140)

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Ferric salts With Na,Co, The borax- | The borax. With CONO, give the same a green mass. bead in either bead is red- the oxide as

blowpipe | The borax- flame is deep brown in the sumes a green reactions as bead is grey blue. outer, and colour; with ferrous salts. in the inner,

grey in the carbonate of and amethyst

inner flame. sodium on in the outer

charcoal, a flame.

yellow incrustation, white when cold.

added is similar in composition to that above it.
indicated opposite in the first column, but of the hydrate.

In the Table which we append to this group we have purposely

unfrequently, but are generally asso

Analysis of The metals of more common occurrence only being included,

IRON (ferrous or ferric), MANGANESE,

Dissolve in hydrochloric acid; boil with a few drops of nitric acid, and ammonia.

A precipitate may contain

Uranium, Aluminium, Chromium, or Iron. The precipitate is washed, and digested with carbonate of ammonium in the cold, then filtered ; if not wholly dissolved, we infer the

absence of Uranium, confirmed by adding acetic acid

and ferrocyanide of potassium.

presence of Aluminium, Chromium, or Iron. Redissolve in hydrochloric acid, and add excess of hydrate of potassium; if the precipitate at first formed is finally entirely dissolved, we infer the

absence of

Iron.

presence of Aluminium or Chromium. Boil the solution. If no precipitate is produced, we infer the

absence of possible presence of
Chromium.

Aluminium,
which may be ascertained by observ-
ing whether the addition of chloride
of ammonium produces a preci-
pitate.

* If a precipitate is in any case obtained, the reactions

omitted to mention the rarer metals, since they not only occur ciated also with but few other bodies.

Subdivision III. the salt may be one of URANIUM, ALUMINIUM, CHROMIUM, NICKEL, COBALT, or ZINC.

add some quantity of solution of chloride of ammonium, and excess of

No precipitate will indicate the presence of

Manganese, Nickel, Cobalt, or Zinc. Add sulphide of ammonium, wash any precipitate which may form thoroughly, dissolve it in nitro-hydrochloric acid, and add excess of hydrate of potassium; the formation of any precipitate will indicate the

absence of

presence of Zinc. This may

Manganese, Nickel, or Cobalt. be con

Redissolve in HCl, and add excess of carbonate of amfirmed by monium; the formation of no precipitate indicates the observing that hydrosulphuric absence of

presence of acid pro- Manganese.

Nickel or Cobalt. duces no precipitate

Acidify with acetic acid, add cyanide of poin this

tassium 'in excess, boil the solution, and add solution,

slight excess of hydrochloric acid ; the formation of no precipitate indicates the

*

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must be referred to, and confirmatory tests chosen.

SUBDIVISION IV.

SALTS OF CADMIUM, COPPER, SILVER, MERCURY, LEAD,

BISMUTH, PALLADIUM, TIN, ANTIMONY, ARSENIC, PLA-
TINUM, RHODIUM, RUTHENIUM, IRIDIUM, OSMIUM, GOLD,
TUNGSTEN, MOLYBDENUM, AND VANADIUM.

The metals of this subdivision bear a very great resemblance to those of the last group, both in the number and the composition of the insoluble salts which they form : two members, indeed, of the present subdivision, cadmium and copper, differ in but few particulars from the general chemical characters of iron, nickel, cobalt, and zinc; but some metals of this class form insoluble chlorides and iodides, as copper and mercury (cuprous and mercurous chlorides), and also silver, lead, and platinum (argentic, plumbic, and platinous chlorides). As a general rule, however, the salts of the present and of the preceding subdivision correspond very closely in relative solubility and insolubility,—the chlorides, sulphates, silicofluorides, &c. of the fourth subdivision being soluble like those of the third, while the chromates, hydrates, carbonates, sulphydrates, sulphides, &c. are insoluble, at least for the most part, and thus resemble the similar salts of the third group. The great characteristic which enables us to arrange the metals whose names are given above into a distinct group, is the precipitation of their sulphides by hydrosulphuric acid gas, not only from neutral, but also from acid solutions,—the ready solubility of the sulphides of the former subdivision in acids being, it will be remembered, one of its distinguishing features. But, in addition to this, a new peculiarity manifests itself in the deportment of the sulphides of the present group, by means of which its further division into · sections is effected. The peculiarity alluded to, is the solubility of a great number of these sulphides in alkaline sulphides, and the insolubility (under the same conditions) of the remainder,

A new feature is also to be observed in the members of this group, namely, their ready decomposition with precipitation of metal by the introduction of a sheet or bar of certain metals

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