Page images

Actual analysis for the detection of the acid constituent.

[graphic][ocr errors][ocr errors][subsumed][ocr errors][merged small]

The precipitate may be BaF, Ba Si,F3, Ba,Õ, Ba, T, Ba,Õi, Ba, PO4, BaBoom, or BaSiO2.

To the solution add dilute HCl, and then divide the liquid into two parts.



If no results are obtained with I., boil the second Evaporate to dry- portion with Na, CO, ; filter from the precipitate ness, add HCl, intro- of Ba,CO,, acidify with HĀ, and add CaCl. duce a slip of turmericpaper. A brown co A preci- | The solution may contain CaBo0,, louration indicates pitate in- | Ca, T, Ca, i, or Ca PO,. Divide Boo

| into two parts. (or the green-alcohol For fame may be obtained,


II. see p. 329);

(also indi- Add Fe, C1z. Boil the solution. An insoluble residue cated in the A white indicates

Prelim. precipitate A white Solution may Si02. Exam.). | indicates precipitate contain

(Ca,Ci) | Ca T indicates (indicated in

Ci prelim. ex.).

[ocr errors]
[merged small][ocr errors]


A residue may be Agl, The solution may contain AgCl, AgCsy, or Ag, Cfy. Boil it with AgBr, (traces of Agi,) AgCy, Ag, Cfdy. concentrated KHO and a frag- Add slight excess of dilute HNO, ; ment of sugar; filter, neutralize collect the precipitate, wash, dry, and with dilute HNOx, and divide ignite it in a porcelain crucible: the Cy into two parts.

compounds are thus almost entirely reduced to the metallic state. Boil the

residue in dilute HNOz. Test with HgCl. Test with A scarlet pre Fe, Cl. A residue may be The solution cipitate of HgI Ared colouration AgCl or AgBr. Wash; may contain indicates indicates | add a fragment of zinc ÅgN0g.

and a drop of dilute

| Add HCl. A a blue H,SO, ; allow to stand precipitate precipitate a quarter of an hour, indicates the Cfy.

filter : to the filtrate previous ex-
(neutralized and then istence of
concentrated) apply the Cy or
starch-test. An orange
colour indicates

the absence of colour


(to be confirmed as


[ocr errors]


The precipitate may be

The solution may contain Fe, Cfyz, which is a blue ppt. and in- Fe, Csyz, which is a soluble *red salt, indicates . . . Cly.

and indicates ... Csy. Fe, Bz

*brown red A. Fe, G

blue black 7. Fe, Qt , blue black Ot.

[ocr errors]
[ocr errors]


brown green Cfdy.

* These reds may be distinguished by adding HgCl; when the colour of Fe,Csy, is discharged, and that of Fe.Ā, remains.


ANALYSIS OF MIXED SALTS. In the recognition of the various basic and acid-radicals which may be present in a mixture of salts, the plans described in the following Tables are to be adopted, with, however, such modifications as the preliminary examinations may suggest. To the methods of preliminary examination already given (see pp. 391, 404) recourse must again be had; indeed, the indications which they afford are often of extreme value in the analysis of complicated mixtures. The methods for preparing the solution of the substance to be analysed will be the same as those already described. (See pp. 392, 408.).

A few words may here be introduced concerning those combinations and mixtures of basic radicals with one another, known as alloys and amalgams. When once in solution, the manner of recognizing their constituents is identical with that adopted in the case of salts ; but nitric acid, moderately concentrated, which is usually employed as the solvent for alloys, leaves many metals unacted upon and undissolved (e.g. platinum, gold, &c.), which require further treatment with hydrochloric or nitrohydrochloric acid. Nitric acid, moreover, partly separates tin and antimony in the form of insoluble compounds, which must then be treated according to the plan described on p. 394.

Throughout the Tables of the present and preceding chapter, the more common radicals are indicated by a conspicuous type. For the detection, &c. of the acid-radicals contained in a mixture of salts, the Tables already given may be employed (see pp. 413, 414); from these Tables, the rarer organic radicals, the reactions of which have been detailed in Chapter VII., are for the most part omitted, since they seldom occur together in the course of analysis, and generally require the employment of very special methods of separation. For these methods, reference must be made either to Chapter VII. or to a comprehensive treatise on Organic Chemistry.

The preliminary examination of the mixture of salts having been accomplished, and its results recorded, the student will then proceed to the actual analysis.


If HCl has been used for the solution of the substance, and no precipitate be assumed to be absent; but if the substance has been dissolved in water i addition as long as any precipitate is produced: when the precipitate ceases, ride of Bi or Sb, or any HSiO.,, which may have been thrown down. Agitate The precipitate may The filtrate is first freed from HNO, by one or two contain

separate Pt and the mass of the rarer allied metals, PbCl, AgCl, or Hg, Cl; 1 given in Table for Group II. If extremely acid, it and also by thus acidi- suspected to contain As in the form of arsenic comfying their alkaline so- of the latter is expelled*, when a rapid stream of H, S lutions, the anhydride pitation of Pb, As, and Mo, it is well to warm the fil.

W,0, time, with H, S. A blue colour on the first passage of and the acids precipitate may be only S, due to the oxidizing action HSbo,

ever, a mass of S might easily mask a small but impor. H, Sb, 0,

suffered to pass unexamined. Collect and wash the H Bz

The precipitate may contain If the filtrate is of a
H. and

Pb, S Sn, Š, previously formed, or
Hg, S Sb, s

evaporated to dryness at | H, U

Bi, S, Sbs moistened with water and may be here precipit Cu, s Ass separation of HSiO, as ated, since they are but cas As, S. sent, the residue should slightly soluble in

Pds Mo, są + not be interfered with. water or acids.

a current of air: the only Examine according to Examine according to Table dered insoluble in acids; Table for Group I.

for GROUP II. bonaceous mass is left,

well to burn the insoluble

[ocr errors]
[ocr errors]


The precipitates produced by the addition of HCl, and remaining undissolved in excess of that reagent, may contain PbCl, AgCl, and Hg, Cl; the anhydride W,03; and the acids HSbO3, H, Sb, O.,,

HB002, HB3, H, 5, and H, U. Boil the precipitate with several fresh portions of water, and wash it, when on

the filter, with hot water.

The solution

The residue may contain may contain AgCl and Hg, Cl; W,03; HSbO3, H, Sb, 07, and H, Ū. PbCI,

Warm with solution of KHO, filter and wash. HB002, HBe

The solution and H, 5.

The residue may contain AgCl and (Hg.),O. may contain

Warm with solution of NH HO.
Add dilute KWO
H, SO,; a

KSbO white precipi

The solution will | The residue will consist of K, H, Sb, O, and contain

(Hg), 0, tate indicates

AgCl. the presence of which may the presence of

The w may be If a reprecipitation be proved by heating the detected by

occurs on addition of dried substance with The acids will

the blowpipe be found in the

reactions, the | HNO3, it indicates | Na, CO, in a bulb-tube, analysis for Sb by the H, Sb


and obtaining the metallic acid-radical. series of

globules of experiments.


[ocr errors]
[ocr errors]
[ocr errors]

* Certain sulphates, as those of Ba, Sr, and Ca, may be precipitated here, the so, being eonverted into H, SO, If insoluble in acids, such precipitate must be examined by fusion.

+ Mo is not perfectly precipitated unless HS is passed into its alkaline solution, which is afterwards acidified.

T 5

« PreviousContinue »