THE ANALYST. 201 INORGANIC ANALYSIS. The Electrolytic Determination of Coppar in Iron. H. Xoch. (Zeit. anal. Chem., 1902, sli., 105-107.)--The copper is first concentrated by treating the iron with dilute sulphuric acid and then separated by electrolyzing the insoluble residue. whether they are the proportion of caoutchouc actually employed by the manufacturer.-F. H. L. * It is not clear whether by these figures the author means the yield of the Henriques process, or202 THE ANALYST. In the case of steel, 100 grammes of the shavings are treated with 400 C.C. of dilute sulphuric acid (specific gravity, 1-06), half of this quantity being first used without the aid of heat, and the remainder added to the hot liquid after completion of the reaction. Crystallization of the sulphates during cooling is prevented by the addition of 500 C.C.of water. The black residue is collected on a double filter, dried, ignited, and dissolved in a large porcelain crucible in a few C.C. of concentrated hydrochloric acid, and the solution evaporated to dryness after the addition of sulphuric acid. The residue is dissolved in about 20 C.C. of water and the same quantity of nitric acid (specific gravity 1*20), the solution filtered, and the filtrate diluted with water to about 120 C.C. A few drops of a 5 per cent. solution of oxalic acid are then added, and the liquid electrolyzed for nine to ten hours with a current of about 0.094 ampere per square centimetre. The positive electrode consists of a spiral of platinum wire 1.3 millimetres thick, which rests upon the bottom of the beaker, whilst the negative electrode is a cylinder of platinum foil 9 by 3-5 centimetres in size.The method requires a slight modification in the case of gray pig-iron, owing to the large proportion of graphitic carbon present protecting the iron from the action of the acid. To obviate this the residue should once more be boiled with about 200 C.C. of sulphuric acid (sp. gr. 1-06> for about thirty minutes before being treated as described above. C. A. M. Rapid Method for the Volumetric Determination of Molybdenum Steel. Francis T. Kopp. (Journ. Amer. Chem. SOC., xxiv., 186.)-Half a gramme of the sample is dissolved in 2 C.C. sulphuric acid (specific gravity 1-58) and 12 C.C. water in a platinum crucible of 100 C.C. capacity, solution being hastened by heating.The solution is then evaporated until white fumes are given off, and cooled ; to the residue 30 grammes fused potassium bisulphate are added, and the whole is then gently heated to a red heat, and kept at this temperature for ten or fifteen minutes. After cooling, the melt is dissolved in 500 C.C. hot water, the solution cooled, transferred to a litre flask, and, after the addition of 100 C.C. ammonia (specific gravity 0-90), made up to the mark with water. After mixing thoroughly 500 C.C. are filtered through a dry filter, 40 C.C. sulphuric acid (specific gravity 1.58) added, and the solution is run through a Jones reductor consisting of a column of zinc 12 inches long and 0.5 inch diameter. To the reduced solution 10 C.C. sulphuric acid are added, and the molyb- denum is titrated with standard permanganate solution.A blank, consisting of 450 C.C. water, 50 C.C. ammonia, and 40 C.C. sulphuric acid, should be run through the reductor and titrated as above, in order to ascertain the error due to impurities in the zinc. For tungsten steels, 1 gramme of the sample is dissolved in 25 C.C. dilute nitric acid, with the addition, after violent action is over, of 10 C.C. strong hydrochloric acid. The solution is evaporated to dryness, the residue baked, and then re-dissolved in 15 C.C. hydrochloric acid. The tungsten will be precipitated as tungsten trioxide. After cooling and diluting with water to 100 c.c., 50 C.C. of the solution are filtered through a dry filter, 10 C.C. of sulphuric acid are added, and the solution (which should be free from tungsten) is evaporated till white fumes are given off, transferredTHE ANALYST.203 to a platinum crucible, again evaporated till white fumes are given off, cooled, and fused with 30 grammes potassium bisulphate, as in the ca8e of steels. For ferro-molybdenums 0.5 gramme of the sample is dissolved in 15 C.C. strong nitric acid in a platinum crucible ; when thoroughly dissolved, 2 C.C. sulphuric acid are added, the solution is evaporated till white fumes are given off, and then treated as for steels. The method gave good results when checked on steels containing known amounts of molybdenum, and also when compared with other methods of estimating molyb- denum. A. G. L. ______ __ - Identification of Metals of the Platinum Group by means of Sodium Peroxide.Leidie and Quennessen. (Bull. SOC. Chim., 1902, xxvii., 179-183.)- Various tests are commonly employed to differentiate the metals of platinum ores, and some of these are both tedious and also require fresh samples of the material to be taken. The authors have made experiments to devise a rapid method in which all the tests can be applied to one and the same sample, and have eventually found that sodium peroxide at a dull red heat is a suitable reagent. The metal, which should be in the finely divided state as obtained by ignition of the salt in hydrogen, is mixed with five or six times its weight of sodium peroxide, and gently heated in a nickel basin over a low gas flame. The mass first blackens and then becomes pasty, but after being stirred with a platinum spatula, and the heating continued, it becomes semi-liguid.The flame is now withdrawn, and the cold contents of the basin cautiously treated with water in the proportion of ten to twelve times the weight of sodium peroxide used. The mixture is now transferred to a tube, and, after standing, the clear liquid is decanted, and the deposit mixed with water and collected on a filter, The oxide of nickel formed will be found in this deposit, and if insoluble oxides or insoluble alkaline salts of the platinum group are also present, it can be readily separated from them by means of the nitrite method previously described by Leidii! (ANALYST, xxvi., 108). The separate metals treated with sodium peroxide in this way give the following results : Osmizwz is completely converted into sodium osmiate, OsO,(NaO),, which dis- solves in water, yielding a yellow solution, On passing a current of chlorine through this solution slightly heated, osmium peroxide, Os04, can be collected in a receiver immersed in ice water.The latier compound may be identified by the formation of potassium osmiate (action of potassium nitrite on heating, or of alcohol and potassium hydroxide in the cold). Ruthe.rzium is completely converted into sodium peruthenate, RuO,(NaO), which in the presence of water yields the ruthenate, RuO,(NaO),. The latter forms an orange solution, which on treatment with chlorine gas, as above, yields a yellow liquid, in which ruthenium peroxide, RuO,, may be identified by the reduction of ruthenium on treatment with potassium hydroxide and alcohol in the cold, or by the formation of a brown sesquichloride, Ru,Cl,, by the action of hot hydrochloric acid.204 THE ANALYST, PalZadium yields an alkaline palladate soluble in water.On neutralizing the yellow solution with hydrochloric acid and then evaporating it after the addition of potassium chloride and nitric acid, ruby red crystals of potassium chloro-palladate, insoluble in a saturated solution of potassium chloride, are formed. Iridium is converted into a basic iridate, IrOs4Na20, which on treatment with water yields a blue solution. On adding a slight excess of hydrochloric acid to this solution, and evaporating after the further addition of potassium chloride and a little nitric acid, black crystals of potassium chloro-iridate are obtained. These are also insoluble in a saturated solution of potassium chloride.Platinum is converted into the insoluble sodium platinate, which remains on the filter with the nickel oxide. The precipitate is dissolved in strong hydrochloric acid, the greater part of the acid subsequently evaporated, sodium nitrite added until the liquid is neutral, then sodium carbonate, and the liquid boiled and filtered. Nickel carbonate remains on the filter, whilst the filtrate contains the double nitrite of platinum and sodium. On evaporating this filtrate to dryness after the addition of hydrochloric acid, the residue dissolved in water and treated with ammonium chloride gives the characteristic crystals of ammonium chloro-platinate.Rhodium is converted partially into the dioxide, Rho,, soluble in hot concen- trated hydrochloric acid, and partially into a sesquioxide, remaining undissolved. The filtrate obtained by treating the mass with hot hydrochloric acid will also contain the nickel. I t is treated in bhe 8ame manner as the platinum solution, and filtered from the nickel carbonate. On heating the filtrate with an excess of hydrochloric acid it becomes rose-coloured from the formation of the double chloride, Rh2Cls.6NaC1, but does not yield a precipitate with ammonium chloride. The following scheme shows the course to be followed in a systematic qualitative analysis : The product of the action of sodium peroxide upon the metal is treated with water, yielding a solution and a precipitate I I B.The solution is colourless. It is rejected. The precipitate is treated with HC1, the liquid filtered and treated with NaNO, and Ns,CO,. 1: ---__ A. The solution is coloured _____- I I Yellow. I Blue. It is neutralized with HCI, and It is heated and treated I evaporated with HNO, and with a current of - KCI. Black crystals insoluble chlorine. I in KCl indicate I I-- ___ The filtered liquid is treated with HC1 in excess and evaporated to dryness, and the A substance is volatilized, Nothing volatilizes. The liquid is neutralized residue in water* I i IRIDIUM. ~ giving a black precipi- with HCI, and evaporated with HNO, and tate with (NH,),S. KC1. Red crystal3 insoluble in KC1 indicate PALL.4nIUN. 1- - I I I L I The solution d!stilld gives The solution distilled gives The solution is light The solution is an insolubIe violet osmiate a black precipitate with yellow, and gives a red, and gives with KOH and alcohol, KOH and alcohol.With p r e c i p i t a t e with n o precipitate or KN02 on heating. No hot HC1 it gives a, brown NHi,C1, insoluble in with NH,CI. brown coloration with hot coloration. excess of NH4C1. RHOI)IUY. HCI. RUTHENIUM. PLATINUM. OSMIUM. C. A. N.TEE ANALYST. 205 A Note on the Determination of Molybdenum in Steel. George Auchy. (Jown. dmer. Chem. SOC., xxiv., 273.)-Not more than 1.308 grammes of the steel are treated with a large excess of strong nitric acid, with the addition of a little potassium chlorate if chromium is present; the nitric acid is evaporated off, the residue boiled with strong hydrochloric acid, evaporated to dryness to separate silica, taken up with strong hydrochloric acid, and the solution evaporated to the first appearance of a, scum.To the solution 5 C.C. hydrochloric acid, diluted to 20 C.C. with water, are added, and after solution is complete the volume of the liquid is made up to 50 C.C. with water, and the solution poured little by little, with constant shaking, into a solution of 20 grammes caustic soda in 100 C.C. water, contained in a 300-C.C. flask. The liquid is made up to the mark with water, mixed, and 250 C.C. are filtered off, acidified with sulphuric acid, boiled down to less than 100 c.c., reduced with zinc, and titrated with permanganate. A blank must be made on a steel free from molybdenum, the same amount of hydrochloric acid and of chromium being present as in the actual determination.Most of the chromium is precipitated with the iron, but a small amount remains in solution. The method gives good results, the caustic soda separation being sufficiently exact for all practical purposes. A. G. L. The Analysis of Metallic Molybdenum and its Lower Oxides. C. Friedheim and M. K. Hoffmann. (Berichte, 1902, xxxv., 791-795.)-The pure molybdenum dioxide used by the authors in their experiments was prepared by reducing molyb- denum trioxide for five to seven hours in a current of bydrogen at a temperature of 450' C , and then heating the mixture of dioxide and unreduced trioxide to a dull red heat in a current of dry hydrochloric acid gas so as to volatilize the trioxide in the form of chloride. For the determination of the molybdenum dioxide in an insoluble molybdenum oxide the substance is slowly heated to the boiling-point with a sufficient quantity of a 10 per cent.solution of ferric ammonium sulphate and twice that amount of dilute sulphuric acid (1 : 5). The molybdenum is dissolved in accordance with the equation Fez(SOe), + Mooz + H,O = 2FeS0, + H2S04 + MOO,, and by titrating the amount of ferrous salt with standard permanganate the quantity of molybdenum dioxide can be obtained. I n the case of an oxide containing lower oxides of molybdenum soluble in water the substance is treated with an excess of acid potassium permanganate solution, and the excess titrated with standard oxalic acid solution. Metallic molybdenum may be analysed by the ferric ammonium sulphate method described above, or the following indirect gravimetric method may be used: The metal, or the compound containing lower oxides, is heated for about an hour, with continual shaking on the water-bath, with a very dilute ammoniacal solution of silver sulphate.After standing for twelve hours, air being excluded, the separated silver is collected on a filter, washed with a very slightly ammoniacal 10 per cent. solution of ammonium nitrate, dissolved off the filter by means of dilute nitric acid, and deter- mined either gravimetrically or volumetrically. C. A. M,206 THE ANALYST. Colorimetric Estimation of Sulphur in Cast Iron. T. Raske. (Stah2 wtd Eisen, 1902, xxii., 333 ; through Chern. Zeit. Rep., 1902, 92.)-Lindlay has described a process for the estimation of sulphur which depends on the fact that in presence of ferric chloride and sulphuretted hydrogen p-phenylenedimethyldiamine hydro- chloride is converted into methylene blue.The sulphur of the iron is therefore to be liberated with hydrochloric acid, the gas passed into sodium hydroxide, and a colorimetric operation carried out. Naske, however, objects to this method that acid produces methyl sulphide as well as sulphuretted hydrogen, that on absorption in caustic soda normal sulphide, hydrosulphide, and polysulphides are formed, that the hydrogen sulphide is not quantitatively taken up, and that the sodium sulphide solution gradually changes into thiosulphate and sulphate. On the other hand, solutions of methylene blue are decomposed-ie., decolorized- by sulphuretted hydrogen and thiosulphate.Lindlay's process ie accordingly only suitable for qualitative purposes, and the same remarks apply to the employment of Lauth's violet, which he has also recommended. F. R. L. An Accurate Estimation of Sulphur in Iron by the Evolution Method. Harry E. Walters and Robert Miller. (Proc. Eng. Soc. West. Pennsylvania, xviii., 83.)-In this method 5 grammes of the sample are weighed out into a porcelain or copper boat, which is then placed in a porcelain or nickel combustion-tube, and heated to bright redness for fifteen to thirty minutes in a current of natural gas or hydrogen. After allowing it to cool in the current of gas, the sample is removed, transferred to a flask, and the hydrogen sulphide evolved as usual by means of hydrochloric acid (1 acid : 1 water).The evolved gases are absorbed in ammoniacal cadmium chloride solution and titrated with iodine. The results given by this method were checked against those given by the ordinary evolution method and by a, gravimetric method, and are almost identical with the latter, the largest difference being 0.004 per cent. in about thirty determinations, whilst the ordinary evolution method in many cases gave very low results, For an ordinary pig-iron fifteen minutes' heating is suecient; for samples containing titanium it is necessary to heat for half an hour. A. G. L. The Determination of Sulphur in Iron Pyrites. R. Auzenat. (Ann. de Chim. anal., 1902, vii., 93, 94.)-The following method is recommended as giving accurate results in a much shorter time, and with less attention to the evaporation, than those obtained by Lunge's method : About 0-5 gramme of the finely powdered mineral, previously dried at 100" C., is weighed into a flask, into which are then introduced successively 20 C.C.of a 10 per cent. solution of sodium cbloride, 10 C.C. of hydrochloric acid, sp. gr. 1.18, and 10 C.C. of nitric acid, sp. gr. 1-5. As soon as effervescence has ceased, the flask is placed in an oil bath provided with a thermo- regulator, and the liquid evaporated to dryness. Under these conditions the tempera- ture can be raised to 120" C, without the liberation of free sulphuric acid. The author's comparative determinations have shown that it is possible to save several hours in this way without fear of loss.C. A. M.THE ANALYST. 207 Rapid Method for Estimating Thorium in Monazite Sand. E. Benz. (Zeits. fiir aqzgew. Chem., 1902, xiii., 309.)-Half a gramme of the finely divided sand is intimately mixed in a platinum crucible with the same quantity of sodium fluoride and 10 grammes of potassium pyrosulphate and gradually heated. When the evolution of gas ceases the crucible is raised to a low red heat and kept at it for fifteen minutes. The melt is extracted first with dilute, then with concentrated hydrochloric acid. The filtrate is nearly neutralized with ammonia, taking care not to produce a permanent precipitate. It is raised to boiling, and 3 to 5 grammes of solid ammonium oxalate are added with stirring. The oxalates fall as a granular precipitate.A little ammonium oxalate solution is added to make sure that che precipitation is complete. After standing all night the oxalates are filtered off, then washed with as little water as possible into a porcelain basin. The filter is washed with hot concentrated nitric acid and water, and the liquid is evaporated almost to dryness. A few C.C. of concentrated nitric acid are added and then 20 C.C. of fuming nitric acid, the basin is covered with a watch-glass and placed upon the water-bath. When the effervescence ceases the liquid is evaporated to dryness; some water is added and again evaporated off. The residue is then dissolved in water and ammonium nitrate solution is added; the liquid is warmed to 60" or SO", and 20 C.C. of distilled hydrogen peroxide (2 or 3 per cent.) are added.A precipitate of thorium peroxide is formed, which may be coloured yellow by minute traces of cerium peroxide. This is washed with hot water containing some ammonium nitrate, and when half dry is ignited in a platinum crucible and weighed as Tho,. The solution is filtered. A. M. A Rotary Cement Kiln for Use in the Laboratory. E. D. Campbell. (Journ. Amer. Chem. SOC., xxiv., 249.)-The author describes a small rotary furnace for cement burning which gave very satisfactory results. The furnace itself consists of an 8-inch steam-pipe 32 inches long, the lining being made of four sections of magnesite tubes packed into the steel jacket with asbestos, the asbestos being mixed at one end for a distance of 2 inches with fire-clay and sodium silicate. The rotary is turned by means of a one-seventh horse-power electric motor, and heated by means of a Hoskins hydrocarbon burner. The temperature is controlled by means of a Le Chatelier thermocouple, the wires of which pass through a double-bored porcelain tube covered for a distance of 8 inches with platinum foil. A fixed couple is kept at a point 3.5 inches from the hot end, and the temperature at other points is taken by means of a moving couple. The hottest zone is at a distance of 6 inches from the discharge end. The temperature at this point can be raised up to 1,630" C., which is too high for most mixtures. About 4,500 grammes of material are usually used for one run, yielding 2,500 to 2,800 grammes clinker, at the rate of about 600 to 700 grammes clinker per hour from the first appearance of clinker to the time feeding is stopped. A. G. L.