METHODS FOR THE DETERMINATION OF VANADIUM. THE importance which has recently been attained by the element vanadium in metallurgy has caused considerable research into rapid and accurate means for its determination. Two recently published volumetric methods are here given. The first of these was worked out by Mr. H. F. Watts of Boulder, Colo., and appeared in the Western Chemist and Metallurgist for November. The second is a colorimetric one devised by Mr. Arnold Wm. Gregory, an English chemist, and was published in a recent issue of CHEMICAL NEWS (see vol. c., p. 221). Fill a 500 cc. beaker half full of cold water and transfer the cold crucible containing the melt to it. Care should be taken at this point as the reaction between the peroxide and water is violent. It is well to float the crucible in the beaker, cover with a large watch-glass, and add water to the contents of the crucible a few drops at a time from a wash-bottle. When solution is complete, remove and wash the crucible, heat to boiling, and pass a current of carbon dioxide through the solution until saturated. Remove from the heat, allow to settle, and pour through a filter supported on a platinum cone. Wash three times by decantation and three times on the filter, using hot water containing a little sodium carbonate. Suction can be applied toward the end of the operation if found necessary. The filtrate is brought just acid with nitric acid, boiled, and the vanadium precipitated with lead acetate; the slight excess of nitric acid being corrected by the addition of a grm. or two of sodium acetate. The precipitate of vanadate of lead is separated by filtration, and dissolved in a small quantity of dilute nitric acid. To the solution add 10 cc. concentrated sulphuric acid, evaporate to fumes, cool, add cold water and separate the sulphate of lead by filtration, catching the filtrate in a flask. The filtrate, which may amount to 150 cc., is boiled and reduced by sodium sulphate, using I grm. and adding in successive small portions. The excess of sulphur dioxide is removed by boiling; for convenience in testing this point fit a stopper and delivery tube to the flask. When the escaping steam no longer decolorises a dilute solution of permanganate of potash, held in a small beaker, the boiling is stopped, and the hot solution titrated with standard permanganate. The iron factor multiplied by o'916 equals vanadium. If the material contains arsenic it will be necessary to remove it. A convenient point at which to do this is after right strength. Heat the solution to boiling, and pass a current of carbon dioxide gas. From this point the method is carried out as described above. For Products containing much Silica, not readily decomposed by acids, the method of heating with sodium peroxide may be used, but in this case it will be necessary to remove the silica. The filtrate from the iron, after slight acidification with nitric acid, is made alkaline with ammonia, and 3 or 4 grms. of ammonium carbonate added. The beaker is put on a warm plate and allowed to stand for an hour with occasional stirring. The voluminous precipitate of silica is separated by filtration on a 12 cm. filter supported on a platinum cone, using suction. This precipitate, although somewhat inclined to be sticky, is not difficult to filter if suction is used. The washing with hot water, containing a little ammonium carbonate, must be thorough. Ten or twelve times is not too much, churning up the precipitate well with the stream from the wash-bottle. The filtrate now freed from the greater part of the silica is again made slightly acid with nitric acid, and the precipitate with lead acetate made as before. When using the acid method of decomposition, it is not always safe to assume that the vanadium is all extracted by treatment of the ore crushed to 80-mesh or coarser, with dilute nitric acid, as is sometimes recommended. Some vanadiferous sandstones yield to this treatment, but not all, and the writer has repeatedly found vanadium in residues treated in this manner. To make sure of complete extraction the ore should be finely ground in an agate mortar and decomposed first with aqua regia. The direct reduction and titration of the vanadium in the presence of the accumulated salts of the analysis is inaccurate, the end-point being uncertain and successive reductions generally failing to check; so it is always necessary to separate the vanadium from these by precipitation with lead acetate, the titration of pure vanadium solutions being exact. If rapid approximate results are wanted, the filtrate from the iron residue may be acidified with sulphuric acid and the solution reduced and titrated. The method as described has the advantage over the ammonium carbonate method in that the separation of the iron and vanadium is performed, in nearly every case, at a single operation, and obviates the necessity of a resolution and re-precipitation of the iron residue. A clean separation can be made on iron vanadate, using 300 mgrms. of substance. The carbon dioxide is used to prevent bumping, although in some cases its use apparently gives a cleaner separation, due possibly to the tendency of the alkaline carbonates formed to hold vanadium in solution. - The Chemical Engineer, x., No. 6. PROCEEDINGS OF SOCIETIES. ROYAL SOCIETY. Ordinary Meeting, January 13th, 1910. the first reduction by sodium sulphite. Pass hydrogen Sir ARCHIBALD GEIKIE, K.C.B., President, in the Chair. sulphide, filter, boil out excess, and titrate. A correction from the burette reading should be made as follows:-To 150 cc. of water in a flask add 10 cc. sulphuric acid and I grm. sodium sulphite. Boil out the sulphur dioxide and titrate. The amount of permanganate used to colour the solution should be deducted from the assay. This correction usually amounts to 0.2 cc. Method for Ores.-Treat 1 grm. of the finely ground ore (less if high grade) with 10 cc. of aqua regia, and evaporate to dryness. Add to cc. nitric acid, 1.20 specific gravity, and digest on the hot plate for a few minutes. Filter off the silica, &c. Nearly neutralise the filtrate with caustic soda, and pour it with constant stirring into a hot solution of caustic soda contained in a large beaker. A stick of caustic soda dissolved in 200 cc. of water is about the PAPERS were read as follows: "Atomic Weight of Strontium." By Sir EDWARD THORPE, C.B., F.R.S., and A. G. FRANCIS. "Approximate Arithmetical Solution by Finite Differences of Physical Problems involving Differential Equations, with an Application to the Stresses in a Masonry Dam.” By L. F. RICHARDSON. "Method of Determining the Viscosity of Gases, especially those Available only in Small Quantities." By A. O. RANKINE. Recombination of Ions at Different Temperatures." By Dr. P. PHILLIPS, CHEMICAL NEWS, Chemical Notices from Foreign Sources. Jan. 21, 1910 "Electricity of Rain and Snow." By Dr. G. C. SIMPSON. This paper relates to measurements of the electricity of rain made in continuation of those described at the beginning of last year (Phil. Trans., 1909, Series A, ccix., 379-413); and, in addition, to a series of measurements of the electricity of snow made during the winter of 1908-09. All the main conclusions drawn from the previous work have been confirmed, and it may now be stated with confidence that in Simla (a) More than three times as much positive as negative electricity is brought down by the rain. (b) The heavier the rainfall, the more likely is it to be positively charged. (c) Light rain is, as a rule, more highly charged than heavy rain, irrespective of whether the charge is positive or negative. With regard to the electrification of snow the measurements indicate that in Simla (d) The positive charge carried down by the snow is between three and four times as great as the negative charge. (e) Snow is generally more highly charged than rain. "Polarisation of X-rays compared with their Power of Exciting High Velocity Cathode Rays." By L. VEGARD. CHEMICAL NOTICES FROM 35 | from acetylene tetrabromide, is very stable and forms characteristic crystals. Alkaline mercury cyanide solution gives with dichlorethylene a good yield of mercuric chlor acetylide, Hg(C: CCI)2, which, when warmed with potassium cyanide and caustic potash, liberates perfectly pure chloracetylene. Bromacetylene can be prepared similarly. Both substances yield metallic compounds similar to those obtained with acetylene, and there seems to be no reason for rejecting the usual formulæ CH: CC1 and CHCBr. Besides the normal silver, copper, and mercuric salts, monochloracetylene yields trichlormercury - acetic acid, (CIHg)3C.CO2H, with mercury chloride. When chloracetylene is led into ammoniacal silver.nitrate solution, the white precipitate obtained very readily turns brown in air, and after being dried explodes. With cold saturated mercury chloride solution chloracetylene gives tris-chlormercury-acetic acid, (CIHg),C.CO2H. Osmium.-A. Gutbier and K. Maish.-Pure osmium metal was converted into sodium hexachloro-osmate, and by double decomposition with alkaline chlorides the rubidium and cæsium hexachloro-osmate were obtained. They form octohedral crystals of the regular system, which are soluble in cold water. The pure aqueous solutions decompose very readily in air, becoming darker, until finally a fine black powder separates. They dissolve in dilute hydrochloric acid, giving stable solutions from which they can be re-crystallised. The compounds are anhydrous and are stable in dry air. They correspond in chemica! behaviour to the hexachloroplatinates, as well as in thei. FOREIGN crystallographic character. NOTE.-All degrees of temperature are Centigrade unless otherwis expressed. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Vol. cxlix., No. 21, November 22, 1909. New Syntheses of Vanilline.-A. Guyot and A. Gry.-Mesoxalic ether or any aß-diketonic ether, when added to a solution of zinc chloride in acetic acid, gives condensation products, e.g., methyl paraoxymetamethoxyphenyltartronate, which are transformed quantitatively into vanilloyl carbonic acid by oxidation, and the acid can be decomposed into vanillin and carbon dioxide by any of the methods described by Tiemann, Gassmann, or Bouveault. The yield of vanillin is good (70 to 80 per cent of the theory), and the substance is obtained in the pure state, quite free from isomers and resinous matter. Condensation Products of Camphor. - Marcel Guerbet.-Montgolfier has shown that when the mixture resulting from the action of sodium on a toluene solution of camphor is heated to 280° in a closed vessel, a certain proportion of campholic acid is formed together with neutral oily substances. Montgolfier thought that they consisted of colophenic hydrocarbons, (C10H16)n, but when they are subjected to fractional distillation, products are obtained which contain too much oxygen to be derived from colophene. The fractions which pass over between 326° and 335° give crystals from which definite compounds C20H300 and C20H320 can be separated. The C=C first is bornylene camphor, C8H14 CH2 C8H14; CH-CH CO while the second is C8H14 CH2 Cs CO by the action of nascent hydrogen on the former. Berichte der Deutschen Chemischen Gesellschaft. Metallic Salts of Monochlor- and Monobromacetylene.-K. A. Hofmann and H. Kirmreuther.Mercuric tribromethylenide, Hg(CBr: CB12)2, prepared Platinum.-A. Gutbier and Fr. Bauriedel. If a solu tion of an organic ammonium bromide is added drop by drop to a solution of hydrogen platinum bromide, and the crystalline precipitate re-crystallised from hydrobromic acid, the hexabromoplatinates are obtained in the pure state. Their melting-points could not be determined with absolute certainty, as the substances liquefy only at very high temperatures and begin to change colour previously. They usually dissolve in water at the ordinary temperature, giving beautiful red liquids, and can be re-crystallised from unless a small quantity of hydrobromic acid or water is They are practically insoluble in absolute alcohol present, when again they form red liquids. All solutions are yellow when diluted. Concentrated caustic soda in excess colours the solutions yellow; they become colourless on warming. Ammonia produces at the ordinary temperature a yellow coloration which disappears on warming. Hydrazine hydrate decolorises the solution at the ordinary temperature, platinum being separated and nitrogen evolved. water. Molecular Weight of Caoutchouc in Latex.-F. Willy Hinrichsen and Erich Kindscher.-The determination of the molecular weight of caoutchouc in benzene solution by the method of the lowering of the freezingpoint gives the value 3173 for the molecular weight. This is only the lower limit, for it is possible that in the latex some constituents soluble in benzene are present which would lower the freezing-point. This result appears to show that Weber's theory of the polymerisation of a hydrocarbon of low molecular weight is incorrect, and that the original caoutchouc possesses a very high molecular weight. Reaction for Polybasic Acids and a New Reaction for Titanium. Jean Piccard. In reductions with titanium trichloride certain acids act as catalytic agents to accelerate the reaction, and it is found that, in general, monobasic acids have no action, while polybasic acids act as catalysers. Hence this reaction can be used as a test of the basicity of an acid. It is interesting to notice that hydrofluoric acid is very strongly active, which confirms the assumption of the polymerisation of the acid to form H2F2 molecules. It is already known that the salts of trivalent titanium give with oxalic acid in aqueous solution a yellow coloration. Pyrocatechin also gives an orange. yellow coloration with titanium trichloride, and this colour reaction is much more marked than that with oxalic acid. If the dilution is not too great, a red-brown amorphous Messrs. precipitate is obtained, forming a black insoluble powder LONGMANS & CO.'S LIST. on drying. It appears to be a mixture of various compounds. If the dilution is greater the formation of the yellow coloration is a very sensitive test for titanium, fifteen times as sensitive as the hydrogen peroxide reaction. Pyrocatechin must be present in excess, and mineral acids prevent the reaction, while alkalis, alkaline carbonates, or ammonia weaken it. Preparation of Colloidal Solutions of Metals by Ultra-violet Light.-The Svedberg.-If a metal, the surface of which has been freed from a layer of oxide, is placed in a shallow dish, covered with a dispersion agent, and subjected to the radiation of a quartz mercury lamp, after a few minutes the liquid shows under the ultra-microscope the characteristic appearance of a colloidal solution. ferent metals behave differently in different dispersion agents. Silver, copper, tin, and lead very readily yield colloidal solutions, particularly the last-named, while platinum, aluminium, and cadmium show no tendency to form them. Dif Existence of True Percarbonates and the Difference between them and Carbonates with Hydrogen Peroxide of Crystallisation.-E. H. Riesenfeld and B. Reinhold. By the electrolysis of a solution of potassium carbonate under suitable conditions, anhydrous, nearly pure, potassium percarbonate can be prepared. When concentrated neutral potassium iodide solution is added to percarbonates, iodine instantly separates, while the hydrogen peroxide addition products of the carbonates are decomposed by this reagent giving off oxygen. This reaction can be used to distinguish percarbonates and peroxides. True percarbonates are formed only by the electrolysis of alkali carbonate solutions. All the salts hitherto obtained by the action of hydrogen peroxide on alkaline carbonates appear to be carbonates with hydrogen peroxide of crystallisation. MEETINGS FOR THE WEEK. RECENT ADVANCES IN PHYSICAL AND By A. W. STEWART, D.Sc., RECENT ADVANCES IN ORGANIC CHEMISTRY. By A. W. STEWART, D.Sc., Lecturer on Stereochemistry in University College, London. With an Introduction by J. NORMAN COLLIE, Ph.D., LL.D., F.R.S., Professor of Organic Chemistry in University College, London. 8vo. 7s. 6d net. "To anyone who has knowledge enough to know of the vast extent of this subject, but not a courage sufficiently brave to attack it, we would advise him to peruse this excellent work."- Chemical Trade Journal. THE FUNDAMENTAL PRINCIPLES OF CHEMISTRY. An Introduction to all Text-books of Chemistry. By WILHELM OSTWALD. Authorised Translation by HARRY W. MORSE. 8vo. 7s. 6d. net. A DICTIONARY OF APPLIED CHEMISTRY. By T. E. THORPE, C.B., F.R.S., Phil.D., D.Sc., &c. Complete in Three Volumes, Half-bound. Vol. I., with 239 Illustrations, 8vo., £2 2s. Vol. II., with 240 Illustrations, 8vo, £2 2s. Vol. III., with 352 Illustrations, 8vo., £3 3s. THE PRINCIPLES OF CHEMISTRY. By D. MENDELÉEFF, Professor of Chemistry in the University of St. Petersburg. THIRD ENGLISH EDITION. Edited by THOMAS H. POPE, B.Sc., F.I.C. With 110 Illustrations. 2 vols. 8vo. 32s. net. MONDAY, 24th.-Royal Society of Arts, 8. (Cantor Lectures). "Tex- HIGHER MATHEMATICS FOR STUDENTS OF tile Ornamentation," by Alan S. 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Method of Research.-Chap. III. Radiation of the New Radio-active Substances.-Chap. IV. Communication of Radio-activity to Substances Initially nactive.-Nature and Cause of the Phenomena of Radio-activity. CHEMICAL NEWS OFFICE, 16, NEWCASTLE ST., FARRINGDON ST., E C. HALDENWANGER Can be obtained from all businesses which deal in Chemical Apparatus. London: Printed and Published for the Proprietor by EDWIN JOHN DAVEY, at the Office, 16, Newcastle Street, Farringdon Street, E.C. January 21, 1910 |