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an orange-red heat, with potassium chloride as a flux, the crystals formed contain 60-36-61.82 per cent. of manganese, which indicates a very high degree of condensation of the manganite. In order to ascertain if this result is due to the action of aqueous vapour on manganese volatilised with the alkaline chloride, experiments were made with a flux of potassium sulphate, which is not volatile. Under these conditions, with an open crucible, no manganite is formed, since oxygen is absorbed from the air and regenerates the manganate. If the crucible is closed, the product consists of black lustrous crystals of trimanganese tetroxide with a small quantity of an alkaline manganite.

Potassium manganite polymerises as the temperature rises, the limit being the formation of trimanganese tetroxide. This condensation is analogous to the condensation of hydrocarbons with loss of hydrogen. The manganite forms complex products, the manganese accumulating in the molecule like the carbon in the hydrocarbons, but the energy of the acid diminishes as its molecular weight increases, the change culminating in the formation of the non-acidic oxide Mn,O,, with elimination of the alkali.

The tendency of aqueous vapour to decompose manganates is assisted by the tendency to form potassium or sodium hydroxide. When potassium manganate is heated in a current of aqueous vapour, the product at a dull red heat consists of needles of the manganate K20,7MnO2; at a somewhat higher temperature the product is K20,8MnO2; at about 800°, K,O,10MnO2; after two hours at 1000°, K2O,12MnO2; after another hour at the same temperature, Mn,O1 ; and after half-an-hour at an orange-red heat, MnO. C. H. B.

Action of Sulphuric Acid on Potassium Permanganate. By B. FRANKE (J. pr. Chem. [2], 36, 31-43).—When the green solution obtained by dissolving potassium permanganate in sulphuric acid is exposed to direct sunlight in presence of moist air, manganese heptoxide separates and then decomposes into manganese dioxide, manganese trioxide, and ozone (?), which is given off as a blue gas. The latter is insoluble in water, but disappears when brought into contact with sulphuric acid or absolute ether.

Manganese trioxide, MnO3, is formed as a dark-red mass when the green solution of manganese oxysulphate is distilled in presence of water; it is best prepared by decomposing the green solution with potassium carbonate. The red fumes are passed into a U-tube surrounded by a freezing mixture in which they condense to a dark-red amorphous mass. The green solution employed should be free from manganese heptoxide. The trioxide has a peculiar odour, and volatilises at about 50° as a violet vapour, with partial decomposition into crystalline manganese dioxide and oxygen; this decomposition is complete when the substance is heated. It is sparingly soluble in water; a litre of water containing 50 mgrms. of the substance has an intense red colour. When the vapour is passed into aqueous soda or potash, alkaline manganates are produced. The reaction employed for detecting small quantities of manganese by means of potassium chlorate depends on the formation of the trioxide.

Manganic acid is formed when manganese trioxide is passed into water; it is very unstable and decomposes into manganese dioxide, oxygen, and dimanganic acid.

Cl

When cooled ether containing hydrogen chloride is treated with potassium permanganate, a dark-green solution is obtained which contains manganous manganese chloride, Mn<>MnCl. In presence of an excess of ether, the green solution is decomposed and a blue solution formed; the latter contains manganese tetrachloride. When the blue solution is saturated with hydrogen chloride, an oily green liquid containing the compound MnCl,(HCl)2, is formed (compare Christensen, this vol., p. 335).

N. H. M.

Hydrochlorides of Ferric Chloride. By ENGEL (Compt. rend., 104, 1708-1711).-Hydrochloric acid produces no precipitate in very concentrated solutions of ferric chloride, and gaseous hydrogen chloride causes the liquefaction of the hydrates FeCl + 5H2O and FeCl + 12H2O. These facts indicate the formation of hydrochlorides of the chloride.

When solid commercial ferric chloride is treated with a current of hydrogen chloride, it yields a liquid containing a dark-brown solid of variable composition, which may be separated by decantation or by filtration through glass-wool. If the filtered liquid is evaporated over potash in a vacuum, it yields the hydrate FeCl + 12H2O; if heated at 100° for several hours, it gives off hydrogen chloride, and when cooled slowly deposits large, deep garnet-red crystals of the hydrate FeCl + 5H2O. By this method, the pentahydrate can readily be obtained in large quantity, and constitutes an excellent material for the manufacture of officinal preparations of ferric chloride.

If the pentahydrate is treated with a current of perfectly dry hydrogen chloride, it rapidly liquefies, and when saturated with the gas at 25° and then cooled to 0°, it yields large, thin, transparent, amber-yellow lamella, which, when dried over phosphoric anhydride, have the composition Fe,Cl,2HCl + 4H,O. It is very deliquescent. All the hydrochlorides of chlorides hitherto obtained contain water. As a rule they are more soluble than the corresponding chlorides.

C. H. B. Hydrochloride of Ferric Chloride. By P. SABATIER (Compt. rend., 104, 1849-1850).-The hydrochloride of ferric chloride, FezCl, 2HCl, 4H2O, recently described by Engel (preceding Abstract), was obtained by the author six years ago (Bull. Soc. Chim., 1881, 197), in the form of yellowish-brown, translucent, deliquescent lamellæ, by the action of hydrogen chloride on pentahydrated ferric chloride, or by the action of the gas at the ordinary temperature on a mixture of anhydrous ferric chloride and the pentahydrate. C. H. B.

Residues obtained from Steel and Zinc by the Action of Acids. By OSMOND and WERTH (Compt. rend., 104, 1800-1802).— When annealed steel is dissolved in dilute hydrochloric acid at the positive pole of a Bunsen element, it yields a skeleton of graphitoidal plates, which the authors term cement of steel. This residue consists

mainly of iron and carbon, but also contains water and oxygen. Tempered steel yields only a small quantity of residue, which contains comparatively little iron. The following table gives the composition of the residues from steel which originally contained 0.49 per cent. of carbon, and had been subjected to different mechanical treatment:

:

[blocks in formation]

The residues, especially that from tempered steel, explode when dried in a hot-air bath. When dried in a vacuum, they not unfrequently undergo spontaneous combustion. It is obvious that it is not only steel containing platinum that yields the residues first observed by Faraday.

Similar residues are obtained from impure zinc.

[blocks in formation]

These residues are graphitoidal in appearance, but contain no water and are not explosive. The first corresponds in composition with the formula Pb2ZnSn, and the second with the formula Pb2Zn.

The conditions of cooling modify the proportion, composition, and form of the residue from one and the same alloy.

C. H. B.

Paratungstates. By C. GONZALEZ (J. pr. Chem. [2], 36, 44—56). -The following salts were prepared from sodium paratungstate which is obtained by adding hydrochloric acid to a boiling solution of commercial sodium tungstate (Na,WO. + 2H2O) until slightly alkaline to litmus. The salts are sparingly soluble or insoluble, and dissolve to clear solutions in water which contains a few drops of hydrochloric acid; after some time, the solution becomes gelatinous from separation of tungstic acid.

Manganese paratungstate, Mn3W7O2 + 20H2O or Mn,W12041 + 34H2O, is a white amorphous powder which does not melt; after ignition, it is yellowish-green. The cobalt salt, CoзW,O2 + 25H2O, is a bright rose-coloured microcrystalline substance which does not melt at a red heat and acquires on cooling a bluish colour. The cadmium

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salt, Cd,W,O2 + 16H2O, is a white, crystalline compound; it cannot be fused, and is orange-coloured after being heated. The silver salt, Ag10W12041 + 8H2O, is a whitish-yellow crystalline substance; it melts at a red heat and solidifies on cooling to a white crystalline mass with a metallic lustre. The zinc salt, Zn, W12041 + 37H2O, crystallises in white needles; when heated, it is yellow and does not melt. The following double salts are prepared by adding a solution of the salt to a boiling solution of sodium paratungstate until the precipitate formed no longer redissolves. The solution is quickly filtered from the slight precipitate and left; after 2-3 hours, the double salt separates. Copper sodium paratungstate, CuNa, W12011 +32H2O, crystallises in slender, bright-blue needles, melts at a red heat, and solidifies to a black lustrous mass. The lead sodium salt, PbNas W12041 28H2O, forms slender white needles; it melts at a red heat, and on solidifying forms a white mass with metallic lustre. The cobalt sodium salt, Co2NaW12041 + 30H2O, is a rose-coloured crystalline compound which melts at a red heat and solidifies to a black mass with a metallic lustre. The calcium sodium salt, Ca,Na,W12041 + 34H2O, is white; it is fusible and solidifies to a black mass. The strontium sodium salt, Sr.Na2W12041 + 29H2O, crystallises in white scales, does not fuse at a red heat, but becomes yellow. (Compare v. Knorre, Abstr., 1886, 597.)

N. H. M.

Zirconium. By O. HINSBERG (Annalen, 239, 253-256).—No organic zirconium-compound is produced by the action of zirconium chloride on zinc ethide. Attempts to prepare zirconium iodide by the double decomposition of zirconium sulphate and barium iodide resulted in the formation of a solution which, on evaporation over strong sulphuric acid, yielded a mixture of iodine and an amorphous powder, soluble in water, probably ZrI(OH)3 + 3H2O. Attempts to prepare zirconium iodide by passing iodine vapour over a red-hot mixture of zirconia and charcoal were also unsuccessful. W. C. W.

Reactions of Vanadic Acid. By A. CARNOT (Compt. rend., 104, 1803-1805 and 1850-1853).—The estimation of vanadic acid in the form of ammonium vanadate (this vol., p. 691) can only be carried out under limited conditions.

In presence of alkaline and ammonium salts, vanadic acid is more easily estimated in the form of barium vanadate. The solution, if acid, is exactly neutralised with ammonia, heated to boiling, mixed with excess of barium chloride, agitated, and cooled quickly out of contact with air. Precipitation is complete. The precipitate is collected, washed, dried, heated, and weighed in the form of 2BaO, V2O. If the liquid which contains the precipitate is boiled, the precipitate agglomerates and becomes firmly adherent to the sides of the vessel.

A slightly ammoniacal solution of vanadic acid containing ammonium salts gives no precipitate with strontium salts. By means of this difference, vanadic acid can be accurately separated from phosphoric and arsenic acids, and, approximately, from molybdic and tungstic acids, the latter being incompletely precipitated from boiling

solutions by strontium salts. The difference can also be utilised for the accurate separation of barium and strontium. The liquid is made alkaline with ammonia, mixed with ammonium chloride and an excess of a soluble vanadate, boiled for a few minutes, and then cooled quickly out of contact with the air. The clear liquid is decanted, the precipitate washed with cold water, dissolved in hydrochloric acid, and the barium precipitated as sulphate. The strontium is precipitated by means of ammonia and ammonium carbonate.

Calcium and magnesium salts give no precipitate with dilute solutions of vanadates, but in concentrated and strongly ammoniacal solutions the vanadic acid is partially precipitated.

When an acid solution containing vanadic acid and an aluminium salt is neutralised with ammonia, the aluminium hydroxide carries vanadic acid down with it. The same result follows if the aluminium is precipitated with sodium phosphate or an alkaline sulphide. In the latter case, the presence of vanadic acid is indicated by the brown colour of the precipitate; chromium hydroxide behaves similarly, and, if in sufficient quantity, will retain the whole of the vanadium.

Vanadic acid, like phosphoric and arsenic acids, is completely precipitated by uranic salts in ammoniacal solutions, and also in presence of small quantities of free acetic acid. In order to estimate the acid in this way, the liquid is nearly neutralised with ammonia, mixed with ammonium acetate and excess of uranium nitrate, and heated to boiling. Complete precipitation is recognised by the reaction with potassium ferrocyanide. The precipitate is washed with pure water, dried, and separated from the filter-paper, which is burnt separately. The precipitate when dried at 100° has the composition

V2O5,2UO3, (NH)2O + H2O;

when heated in presence of air, it loses ammonia and water, becoming V2O5,2UO3, in which form it is weighed. Vanadic acid can be estimated by this method not only in presence of alkalis and alkaline earths, but also in presence of many metals, such as manganese, zinc, and copper, the acetates of which are not decomposed by boiling. It cannot, however, be separated by this reaction from phosphoric, arsenic, tungstic, and molybdic acids.

Ferric hydroxide carries down vanadic acid when precipitated in a solution containing it, but the vanadium can be separated by means of ammonia, ammonium acetate, or ammonium hydrosulphide, provided the precipitation is repeated several times.

Manganese forms a well-defined vanadate, by means of which both the acid and the base can be estimated with accuracy. The vanadic acid solution is mixed with a slight excess of ammonia and ammonium chloride, heated to boiling, and then mixed with ammonium chloride and manganese chloride or sulphate, boiled for two or three minutes, and cooled quickly out of contact with air. The precipitate, which is brownish-yellow and should be free from any brown oxidation-product, is collected, washed with cold water, dried and ignited. It then has the composition 2MnO,V2O5. This reaction cannot be used for the separation of vanadic acid from phosphoric and arsenic acids, but it will effect a partial separation of vanadic and tungstic acids and a

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