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6. Solutions of vanadiates with tincture of galls yield a blackish blue or black mixture.

Vanadiates are usually detected by the tests B, 8, and e.

Of the acid-radicals which contain metals and sulphur, none are of sufficient importance to justify description here. They generally form yellow, reddish brown, brown, or brownish black salts, which correspond closely to the analogous salts containing the same metals combined with chlorine or oxygen. They are generally formed by the solution of the metallic sulphide in sulphide of potassium, sodium, &c. The salts formed by these radicals are termed sulphostannates (M, Sn, S.), sulphoplatinates (M, Pt, S.), sulphorhodiates (MRS), sulphorutheniates (M, Ru, Sz), sulphiridiates (M,Ir, S), sulphosmiates (MOsS2), sulphaurates (MAuS.,), sulphotungstates (MWS2), sulphomolybdates (MMOS,), and sulphovanadiates (MVS.).

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Magnesium white

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Analysis of Subdivision II. The acid-radicals of more common occurrence only being included, the salt may be an OXIDE, SULPHIDE, SULPHITE, SULPHATE, CHROMATE, or TUNGSTATE.

The addition of strong sulphuric acid to the solid salt or its concentrated solution may produce an effervescence; if so, the evidence sought will probably be better obtained with a weaker acid, aided by heat. A gas having an odour of rotten eggs (H,S) indicates a sulphide.

„ „ burning sulphur (S0,) indicates a sulphite.

Further Analysis. Acidify the solution with hydrochloric acid, and warm for some time.

A lemon-yellow precipitate of W,0, would indicate the

original presence of

If no precipitate occurs, the solution may contain a chromate, sulphate, or oxide. Add a few drops of alcohol, and boil for some minutes; if the liquid changes from a reddish yellow to an emerald-green colour, the previous existence of Cro, may be inferred. Add excess of ammonia.

WO,

If no green colour or precipitate occurs, add a few drops of chloride of barium.

A green
precipitate
of Cr, H,O,
would indicate

the original
presence of

CrO,

A white precipitate

of Ba, so would indicate the presence of

SO,

If no precipitate occurs, and the sub

stance under examination is obviously

not a basic radical, 2. e. a metal, we infer the presence of O as

the acid-radical.

SUBDIVISION III.
SALTS OF CARBON, BORON, SILICON, TANTALUM, NIOBIUM,

PELOPIUM, AND TITANIUM, AND OF THE CHIEF COM-
POUND ACID-RADICALS INTO THE COMPOSITION OF
WHICH THEY ENTER.

This group, with the exception of its four latter and rarer members, presents but little analogy with either of the preceding subdivisions. One distinctive feature is, that no member of this subdivision combines directly with hydrogen to form a compound of acid properties, although they combine with almost all metals to form salts. All these acid-radicals, however, form, by union with oxygen, compound acid-radicals, which yield extremely stable salts with hydrogen and metals. Another great peculiarity of this group is the property possessed by carbon of uniting with hydrogen and oxygen, with hydrogen, oxygen, and nitrogen, and with other basic radicals, such as with iron and nitrogen, to form acid-radicals, many of which combine with basic radicals to form salts of great stability: most of such compounds are generally termed “organic," from their frequent occurrence in the animal and vegetable kingdoms, or from being obtained among the products of their decomposition. Examples of such compounds are H,C,H,O,

HC, H, 10, H,Co, C, N succinic acid. "uric acid hydrocobalticyanic acid. Among these bodies many are monobasic, many bibasic, and some tribasic.

SECTION I. SALTS OF CARBON, BORON, SILICON, TANTALUM, NIO

BIUM, PELOPIUM, AND TITANIUM.

The carbides, borides, silicides, tantalides, niobides, pelopides, and titanides.

SECTION II.-SALTS OF THE ACID-RADICALS WHICH CONTAIN

CARBON, BORON, SILICON, TANTALUM, NIOBIUM, PELOPIUM, AND
TITANIUM COMBINED WITH FLUORINE, OXYGEN, OR SUL-
PHUR.
The borofluorides, silicofluorides, carbonates, oxalates, borates,

silicates, tantalates, niobiates, pelopiates, titanates, and sulphocarbonates.

SECTION III. -SALTS OF THE ACID-RADICALS WHICH CONTAIN

CARBON COMBINED WITH NITROGEN, WITH NITROGEN
AND OXYGEN, WITH NITROGEN AND SULPHUR, WITH
NITROGEN AND METALS, WITH OXYGEN AND HYDROGEN,
AND WITH OXYGEN, HYDROGEN, AND NITROGEN.

The cyanides, cyanates, and sulphocyanides; the ferrocyanides, ferricyanides, and cobalticyanides; the formiates, acetates, benzoates, succinates, tartrates, lactates, citrates, gallates, tannates, and urates.

SECTION I.-The carbides, borides, silicides, tantalides, niobides,

pelopides, and titanides. SALTS OF CARBON, BORON, SILICON, TANTALUM, NIOBIUM, PELOPIUM,

AND TITANIUM. The radicals of this third subdivision, although they combine with metals, can scarcely be said to yield saline compounds, since it is with the greatest difficulty that the bodies are made to unite in definite proportions, and then the products of the union partake more of the character of alloys. It is probable that their combinations, especially those of carbon and silicon (or of phosphorus), with the metal, exist diffused through the mass of metal, which presents, in different specimens, different properties. Thus the varieties of commercial iron known as cast-iron and steel are entirely due to the presence of a small difference in the proportion of carbon present, which, after all, never rises above 2 per cent. It is thought that the known carbide of iron (Fe, C) exists diffused in the mass, which also contains carbon in the form of graphite.

Silicon and phosphorus again are known to exert a very deleterious influence upon the quality of iron and of other metals, even when they are present in very small proportion. Numerous compounds of carbon with hydrogen are known; they are termed hydrocarbons. A compound of silicon with hydrogen has been

discovered recently; but neither it nor the hydrocarbons possess acid properties or reactions.

Section II.-The borofluorides, silicofluorides, carbonates, oxa

lates, borates, silicates, tantalates, niobiates, pelopiates, tita

nates, and sulphocarbonates. SALTS OF THE COMPOUND ACID-RADICALS WHICH CONTAIN

CARBON, BORON, SILICON, TANTALUM, NIOBIUM, PELOPIUM, AND
TITANIUM COMBINED WITH FLUORINE, OXYGEN, OR SUL-
PHUR.

The acid-radicals of the present section are for the most part powerful; they possess different degrees of basicity. Those most important to the student will be found to be the compounds the acids of which are termed hydrofluosilicic, carbonic, oxalic, boracic, and silicic. With the reactions of the five acids just named, the analyst should early make himself acquainted.

Of acid-radicals formed by the union of boron with fluorine, one only is known: it is the radical contained in the borofluorides, and is produced when the gas known as terfluoride of boron (BoF,) or its aqueous solution is mixed with a large quantity of water. The water effects a decomposition of the compound BoF, boric anhydride (Bo, 0,) being precipitated, and the compound HBOF, remaining in solution: this compound is hydrofluoboric acid ; and the decomposition which gives rise to its formation is as follows:8B0F, +3H,O=B0, 0, +6HB0F4.

hydrofluoboric

acid. THE HYDROGEN SALT (HB0F) is not known in an isolated state, but only in aqueous solution.

The fluoborides are all soluble in water, as far as has been ascertained. The radical must be recognized in its salts by processes of decomposition.

SALTS OF SILICOFLUORINE, OR SILICOFLUORIDES. This radical (that contained in the silicofluorides) is of much greater importance than the preceding one, but is prepared in precisely the same manner. The method for its preparation has been already given (p. 65). When the gaseous body terfluoride of silicon (SiF) is passed into water, the hydrogen compound of

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