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REVIEW OF AMERICAN CHEMICAL RESEARCH. VOL. VII. No. 5 . ARTHURA. NOYES,Editor ; A. G. WOODMAN,Associate Editor. REVIEWERS: Analytical Chemistry, H . P. Talbot and F. J. Moore ; Biological Chemistry, A. G. Woodman ; Carbohydrates, G. W. Rolfe ; General Chemistry, A. A. Noyes ; Geological and Mineralogical Chemistry, W. 0 . Crosby and C. H . Warren; Inorganic Chemistry, Henry Fay; Metallurgical Chemistry and Assaying, H. 0. Hofman ; Organic Chemistry, J. F. Norris ; Physical Chemistry, H. M . Goodwin ; Sanitary Chemistry, E. H. Richards; Industrial Chemistry, A. H. Gill aod F. H. Thorp.
ANALYTICAL CHEnISTRY. ULTIMATE ANALYSIS. F. J.
MOORE,
REVIEWER.
The Iodornetric Estimation of Arsenic Acid. BY F. A. GOOCH AND JULIA c. MORRIS. AM.1 .SCi., 160, 151-157.Solutions of arsenates are reduced by soluble iodides with separation of iodine. As the reaction is a reversible one, it is necessary, for analytical purposes, to eliminate the oxidizing effect of the liberated iodine. Gooch and Browning ( A m .J . Sa'., 50, 66) accomplished this by boiling off the iodine. The same result would be effected by changing the iodine to hydriodic acid by means of sodium thiosulphate. An attempt to base an analytical procedure upon this principle was made by Williamson (1.Soc. Dyers and Colorisfs, r896, 86-89). According to Williamson, the .arsenic acid could be measured either by the amount of thiosulphate required to bleach the solution, or, after the reduction, the arsenious acid formed could be again oxidized by iodine. If the thiosulphate method is used the titration must be made in a strongly acid solution. This introduces an error on account of the tendency of the hydriodic acid to oxidation in the presence of strong acids, and also because the thiosulphate added is liable to be decomposed before it can react with the iodine. The authors find that when this method is used a correction of -0.003 gram must be applied to each determination of arsenic acid. If the arsenite is oxidized by iodine, the arbitrary correction necessary is reduced to 0.0015 gram. T h e authors consider both methods inferior to that of Gooch and Browning. The Volumetric Estimation of Copper as the Oxalate with Separations from Cadmium, Arsenic, Tin, and Zinc. BY CHARLES A. PETERS. Ant. J. Sa'., 160, 359-367.-Copp:r may be completely precipitated as oxalate in solutions containing the
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Review of A m e r i c a n Chemical Researck.
above metals. T h e precipitated oxalate is then filtered off on asbestos and titrated with permanganate in the presence of sulphuric acid. T h e essentials for complete precipitation are a large excess of oxalic acid and the presence in the solution of a certain minimum amount of copper dependirg in each case upon t h e volume of the solution and the concentration of the oxalic acid. Thus in a solution containing 0.064 gram copper in 50 cc., t h e copper -will be completely precipitated by a gram of oxalic acid. By adding oxalic acid to the point of saturation, the minimum amount of copper required for the same volume of solution is reduced to 0 . 0 1 2 gram.
The Sulphocyanides of Copper and Silver in Gravimetric Analysis. BY R. G. VAN N a u ~ . Am. J . Sci., 160, 451-457.T h e literature contains conflicting statements concerning the practicability of determining copper by direct weighing of cuprous sulphocyanate. T h e author finds the method satisfactory. T h e copper solution is first reduced with ammonium bisulphite and then precipitated by ammonium sulphocyanate. T h e precipitate is filtered off on a Gooch crucible, and weighed after drying a t I IO'. Contrary to the statements of 5ome writers, the precipitate does not retain water a t this temperature. As the sulphocyanate of silver is soluble in an excess of ammonium sulphocyanate, this method cannot be used for the determination of silver, but as the precipitate is insoluble in an excess of silver nitrate it may well be made use of for standardizing sulphocyanate solutions for use in the Volhard method. Method for Graphite in Pig Iron. BY A. B. HARRISON. PYOC. Ezg. SOL.W e s f e m Pa., 16, I 17-1 I8.-One gram of pig iron is dissolved in nitric acid of I . 13 specific gravity, and the solution i i boiled till red fumes are no longer expelled. Two filters are accurately tared and the residue is filtered off, after diluting the solution, which is allowed to run through both filters. T h e filters are washed successively with nitric acid, water, ammonia, alcohol, and ether, and are dried and weighed. T h e filter containing the graphite is then ignited, and the weight of the ash is deducted from the difference between the final weights of the t w o filters. Analysis of Chrome and Tungsten Steels. BY A. G. McKENNA. PYOC. Efzg. SOL.IVesfenz Pa., 16, I I ~ - I Z I . - - A 5-gram sample is dissolved in an evolution flask in a mixture of 30 cc, strong hydrochloric acid and 30 cc. water. T h e gases evolved a r e passed through a cadmium chloride solution in which the sulphur is afterwards determined by titration with permanganate. T h e solution in the flask is evaporated to dryness, and the residue is dehydrated and treated with about IOO cc. water. T h e insoluble residue is filtered off, ignited, and weighed as tungstic oxide and
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silica. The contents of the crucible are then treated with hydrofluoric acid and the silica determined by loss. The filtrate is evaporated with nitric acid to expel the hydrochloric acid, then potassium chlorate is added and the precipitated manganese dioxide is filtered off on asbestos. Then it is dissolved in hydrochloric acid with the addition of a little potassium nitrite. After removal by the basic acetate method, of any iron this solution may contain, the manganese is precipitated by bromine water and weighed as Mn,O,. In the filtrate from the manganese, the chromium is determined by titration with ferrous sulphate and permanganate. For the determination of phosphorvs another j-gram sample is dissolved in hydrochloric acid, and, after the removal of the tungsten and silicon as before, the phosphorus is precipitated as ammonium phosphomolybdate. The author recommends the direct weighing of the “ yellow precipitate.” For the carbon determination a sample of I . j grams is dissolved in the double chloride of copper and potassium. After a half-hour hydrochloric acid is added, and when all the copper has gone iuto solution, the residue is filtered off and burnt in a current of oxygen, using a platinum tube. T h e carbon dioxide evolved is absorbed in a solution of barium hydroxide, and the amount of carbon is calculated from the weight of barium carbonate produced.
Some Rapid Work on Silicons. BY DALTONPARMLEY. Iron Trade Rev., 34, No. 9. I NOROAN IC CHEMISTRY. HENRYFAY,REVIBWER.
The Production of Alloys of Tungsten and of Molybdenum in the Electric Furnace. BY CHARLESL. SARGENT. J. A m . Chem. Soc.) 22, 783-791.-Alloys of tungsten and molybdenum with nickel, cobalt, and chromium were made by heating the dioxides of these metals in an electric furnace with carbon. The amount of carbon used exerted a greater influence in the purity of the metal than did variations in the strength of the current and the duration of its action. T h e product invariably contained traces of carbon and unreduced oxide. Tungsten did not form alloys with bismuth and manganese, while molybdenum alloyed with both of these metals, but would not alloy with copper, which combined readily with tungsten. Neither metal would alloy with tin. Irregular Distribution of Sulphur in Pig-Iron. BY RANBOLLING. ]. Am. Chem. Soc., 22, 798-7gg.-’I’he sulphur was determined in drillings made at intervals of I k inches in a cast bar 12x14inches, and was found to vary from 0.023 per cent. at the bottom to 0.036 per cent. at the top. DOLPH
