152 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Estimation of Manganese in High-speed Steels. C. T. Nesbitt. (Chem. News, 1917,115, 61-62.)-The author was led to this reseazch by the difficulty ex- perienced in procuring bromine. Other oxidising agents were tried for precipitating manganese from the filtrate from a basic separation, but all the methods tried wereINORGANIC ANALYSIS 153 abandoned, either because the results were insufficiently accurate or because the processes involved were too tedious.Failing bromine to complete an analysis begun with an acetate separation, the aathor can recommend only the following modification of the bismuthate process for the estimation of manganese in high-speed steels proper-that is to say, steels containing high percentages of tungsten and chromium, tungsten-chrome-vanadium, or tungsten-chrome-vanadium-molybdenum.. The drillings (1.1 grm.) are dissolved in 12 C.C.hydrochloric acid, 5 C.C. nitric acid are added, and the solution is evaporated to syrupy consistency. Sulphuric acid (7 c.c.) is added, and the sides of the beaker are washed down once with water. The beaker is kept a t the edge of the hot plate for twenty minutes, heated more strongly until the contents give rise to fumes, evaporation being continued for fifteen minutes.This tends to reduce chromium, which is essential to success. The cooled residue is taken up in 30 C.C. of dilute (1 : 1) nitric acid and 20 C.C. water, the solution Boiled and tungstic oxide filtered off on pulp. To the filtrate 15 C.C.concentrated nitric acid are added, the mixture is boiled, and a pinch of bismuthate added. After clearing with sulphurous acid and boiling until the excess is just removed (but not more than a, minute longer or there is risk of chromium re-oxidising), the solution is rapidly cooled and 0-2 grm. sodium bismuthate added. The ordinary bismuthate process is then followed-that is to say, the solution is filtered through asbestos into excess of N/10 ferrous solution, washing with 3 per cent.nitric acid, and the excess of ferrous solution titrated with N/10 permanganate. One C.C. N/1 ferrous solution= 0-1 per cent. manganese. Por success with high-speed steels tungsten must be thoroughly oxidised and removed, and chromium properly reduced by strong fuming with sulphuric acid and final treatment with sulphurous acid.The initial solution in hydrochloric acid actually saves time, although the hydrochloric acid has subse- quently to be expelled, solutions made in sulphuric acid direct being very difficult to evaporate without loss. The method is accurate and twice as fast as any other reliable method. G. C. J. Estimation of Molybdenum by Potassium Iodate: G.S. Jarnieson. (J. Amer. Chem. Xoc., 1917,39, 246-249.)-The method depends. on reduction of the molybdenum to Mo,O, by means of amalgamaked zinc, receiving the reduced solu- tion (which is very susceptible t o oxidation by air) in a hydrochloric acid solution of iodine monochloride, and estimation of the molybdenum by titration with potassium iodate. Unlike the permanganate titeration, iodate carries the Oxidation readily only as far as the stage Mo,O,, further oxidation proceeding so slowly (2 to 3 days) that it is not practicable to wait for it.KIO, + Mo,03 + 2HC1 =Mo,O, + IC1+ KCl + H,O. A Jones reductor, at least 20 em. in height, and preferably longer, is used; it is filled to within 3 cm. of the top with 30-mesh amalgamated zinc resting on a 2 cm, mat of glass wool on a platinum disc. Previously to making a reduation, a 500 C.C.titration bottle is charged with 5 C.C. of iodine monochloride solution, 25 C.C. of hydro- chloric acid, 5 C.C. of water, and 7 C.C. of chloroform, and placed in a pan of cold water to cool the reduced solution rapidly. The reductor, set up in anothsr bot le154 ABSTRACTS OF CHEMICAL PAPERS is heated with dilute hydrochloric acid and 100 C.C.of hot water. When this has run out, the reductor is transferred t o the bottle in cold water, and a measured amount of the molybdenum solution, acidified with 20 C.C. of dilute (1 : 1) hydrochloric acid, and heated to 50" C., is passed very slowly through the reductor. The flask is rinsed with dilute (1 : 2) hydrochloric acid several times, and the washings passed through thereductor and followed by a further 50 C.C.of dilute acid. The exposure of the zinc during the reduction causes no error, as would be the case with a per- manganate titration, because hydrogen peroxide does not react with iodine mono- chloride or potassium iodate. The reduced solution is finally titrated with an N/10 solution of potassium iodate, stoppering the bottle and shaking after each addition, until the chloroform indicator is decolorised.The fully titrated solution has a rose or red colour due to Mo,O,. The blank correction is 1 drop of N/10 iodate. Oxida- tion t o MOO,, although negligibly slow in diffused daylight, is more rapid in direct sunlight, which should theref ore be avoided. The iodine monochloride solution used is made by dissolving 10 grms.potassium iodide and 6.44 grms. potassium iodate in 75 C.C. water, adding 75 C.C. hydrochloric acid and 5 C.C. chloroform, and adjusting to faint iodine colour by violent shaking and addition of dilute solutions of iodate or iodide as required. G. C. J. New Method of Precipitating Platinum Sulphide and Analysis of Platinised Asbestos.V. N. Ivanov. ( J . Rum. Phys.-Chem. Soc., 1916, 443, 527-529; through J. SOC. Chem. Id., 1917, =,290.)-The addition of mercuric chloride to a platinum solution prior to precipitation of the metal as sulphide facilitates the estimation of platinum and allows of accurate results being obtained, but the bulk of the precipitate is greatly increased and injurious mercury vapour is liberated when the precipitate is ignited.The incomplete precipitation of platinum sulphide under ordinary conditions depends on the formation of a stable colloidal solution of the sulphide, and the author finds that the hydrosol is converted into the insoluble hydrogel if magnesium chloride is present in the solution. The method employed is as follows: A weigh& quantity of about 5 grms.of platinum chloride is dissolved in water in a 250 C.C. flask, the solution being made up to volume and mixed. Twenty-five C.C. of this liquid are diluted to about 200 C.C. in a 250 to 300 C.C. beaker, and then treated with a few drops of hydrochloric acid and about 5 grms. of mag- nesium chloride, either in solution or as crystals, per 100 C.C.of liquid. A rapid current of hydrogen sulphide is then passed through the solution until the latter is saturated, the precipitate adhering t o the gas-delivery tube being removed by a piece of filter-paper and the latter dropped into the liquid, which is then boiled unt,il all odour of hydrogen sulphide has disappeared. The platinum sulphide is washed twice by deca,ntation and several times on the filter with water acidified with one or two drops of hydrochloric acid, the wet filter being then charred in a covered platinum crucible and finally ignited in a blowpipe flame. This method gives results in very close agreement with those obtained electrolytically. I n the case of platinised asbestos, this is treated with aqua regia, which dissolves the platinum and also sufficient magnesium salts from the asbestos to render subse- quent addition of magnesium chloride superfluous. Ten grms.of the asbestos areINORGANIC AKALYSIS 155 heated in a Iarge beaker with excess of aqua regicr; (2 parts of hydrochloric and 1 part of nitric acid) on a water-bath until all the black particles disappear from the asbestos and the liquid assumes an orange-yellow colour.The contents of the beaker are care- fully poured into a porcelain funnel, the asbestos, which serves as a filtering medium, being washed free from platinum. The filtrate is made up to a litre in a measuring flask, and 100 C.C. of the solution are evaporated three times to dryness with hydrochloric acid on a water-bath. The residue is dissolved in 50 C.C.of hot water containing 5 C.C. of hydrochloric acid, and the silica and any fibres of asbestos filtered off. The filtrate is diluted with water to about 250 c.c., and the platinum precipitated as sulphide, the subsequent procedure being as described above. With a particular sample of platinised asbestos five estimations of the percentage of platinum present gave results varying.from 7.72 to 7-75 by the electrolytic method, and from 7-75 to 7.77 by the above hydrogen sulphide method. Estimation of Potassium as Perchlorate. G. P. Baxter and M. Kobayashi. ( J . Amer. Chem. SOC., 1917, 39, 249-252.)-The authors confirm the conclusion of Davis (ANALYST, 1913, 38, 47) and of Thin and Cummhg (ANALYST, 1915,40,296) that Davis's modification of the perchlorate method, in which strong alcohol saturated with potassium perchlorate is used to wash the precipitate, is highly accurate.They point out that where the ratio of sodium to potassium is high, the first precipitate may contain sodium, but this can readily be eliminated by washing the precipitate once or twice by decantation with a saturated solution of potassium perchlorate in alcohol, dissolving it in a, Iittle water, and evaporating once more after addition of a, little perchloric acid.The authors use a platinum sponge crucible and dry at 200" C. in an electric oven, whereas Davis used tared filters and dried at 100" C. G. C . J. Titration of Some Bivalent Metal Sulphates by the Conductivity Method. H. S. Harned. ( J . Amer. Chem. SOC., 1917,39,252-266.)-Much sharper end-points are obtained by the use of barium hydroxide than by the use of sodium hydroxide, for, when barium hydroxide is used, the conductivity falls very much more rapidly until the end-point is reached, so that the change to increasing conductivity a t the end-point is much more marked.The use of barium hydroxide involves titration out of contact with air, for which purpose a suitable cell is described and illustrated in the paper.Any free sulphuric acid in the solution to be titrated is readily neutralised by means of barium hydroxide and a suitable indicator (phenolphthalein) before commencing the titration proper. The method affords a convenient and accurate means of estimating magnesium in presence of calcium. Copper must be titrated at a boiling temperature, or oxysulphates separate and low results are obtained.The method is less exact for nickel and cobalt, owing to the difficulty in neutralising solutions of nickel and cobalt salts without precipitating nickel or cobalt hydroxide. The best modification devised by the author gave results about 3 per cent. low with these metals. Cadmium appears to form a stable oxysulphate which makes the method inapplicable.G. C . J.156 ABSTRACTS OF CHEMICAL PAPERS Interference of Thiocyanates, Ferrocyanides, and Ferricyanides in the Detection of Iodides with Palladium. L. J. Curtman and B. R. Harris. ( J . Arner. Chem. Soc., 1917,39, 266-270.)-Kern (Chem. News, 1875, 32,242; 1876, 33, 184) called attention to the interference of thiocyanates, ferrocyanides, and ferri- cyanides with the precipitation of iodides as palladium iodide, but he supplied no quantitative data. Whereas, in absence of interfering substances, 1 mgrm. of potassium iodide in 5 C.C. of solution gives a distinctly visible black precipitate in a transparent light brown mother liquor, in presence of 5 mgrms. of thiocyanate not less than 5 mgrms. of iodide can be detected with certainty, owing to the precipitation of reddish floccu- lent palladious thiocyanate. Similarly, 10 mgrms. of thiocyanate will inask any quantity of iodide much less than 10 mgrms. The interference of ferrocyanides and ferricyanides is even greater if the test be made in the cold, but can be greatly diminished by boiling the solutions for fifteen to thirty seconds about ten minutes after the addition of the reagent. Under these conditions, ferrocyanides and ferri cyanides interfere with the test less than thiocyanate. G. C. J.