THE ANALYST. 437 INORGANIC ANALYSIS. Method for the Estimation of Iron, Aluminium, and Phosphoric Acid, when occurring together. T. Cooksey. (Proc. Roy. Soc., New South Wales, 1908.)-As most of the results obtained in the method depend on the estimation of the phosphoric acid left in the filtrates, a description is first given of a volumetric method for the estimation of this acid, depending on its precipitation as tricalcic phosphate ; the process is a modification of the one described previously by Emmer- ling (Laizclw. Verszuhsstat., 1886, 429), and is especially applicable to the estimation of phosphates in the ashes of such articles of food as milk, vinegar, wines, etc., which do not contain iron or aluminium. The ash is dissolved in hydrochloric acid, a drop of methyl-orange is added, and potassium hydroxide solution is run in until the solution is just slightly acid.The solution is then boiled to expel carbon dioxide, an excess of calcium chloride solution and a few drops of phenolphthalein are added, and the mixture is neutralised by the addition of ;G potassium hydroxide solution ; the point at which the methyl-orange just becomes yellow is noted, and the addition of the potassium hydroxide is continued until a slight but permanent pink coloration is obtained. The number of C.C. required between these two points corresponds with the amount of phosphate present, 1 C.C. of & solution being equivalent to 0-00355 gram of phosphoric acid (P205). Provided that there is an excess of calcium chloride present, magnesium does not interfere with the estimation.Estimation of Iron and Aluminium in the absence of Phosphoric Acid.-To a slightly acid solution containing the iron and aluminium, sodium phosphate (NaH,PO,) is added in known quantity, together with a drop of methyl-orange. Decinormal potassium hydroxide solution is then run in until a yellow coloration is obtained, the whole is warmed to promote coagulation of the precipitate, and the latter is collected on a filter, and washed. The phosphate in the filtrate is then estimated as described above, and the difference between the amount found and that added originally gives the quantity precipitated with the iron and aluminium. The former is precipitated as Fe,(PO,),, and the latter as Al,(PO,),. The iron is then438 THE ANALYST.estimated separately by the iodine method, which depends on the liberation of iodine from potassium iodide by a ferric salt. The iodine is titrated with thiosulphate solution, and one atom of iodine is equivalent to one atom of iron. Knowing the amount of iron and of the total phosphoric acid in the precipitate, the quantity of aluminium can be calculated. Estimation of Iro?a, Aluminium, and Phosphoric Acid when present together in solution.-The method is as follows: To the solution, which must be suficiently acid to produce a yellow colour and not a reddish one with the iron present, is added a, definite quantity of standard sodium phosphate solution. If the solution is too strongly acid, it may be partially neutralised. After the addition of a little methyl- orange, & potassium hydroxide solution is run in until the pink coloration has just disappeared, the mixture is diluted to a volume of about 90 c.c., and warmed on the water-bath.The precipitate is collected on a filter and washed with hot watsr until free from chlorides. The filtrate is treated with an excess of calcium chloride, then rendered slightly acid by the addition of a few drops of & hydrochloric acid, using methyl-orange as indicator, and boiled to expel carbon dioxide. The procedure is the same as that described previously. The precipitated phosphates collected on the filter are dried and ignited at a moderate temperature until constant in weight. The iron is then estimated by dissolving the phosphates in hydrochloric acid, and apply- ing the iodide method.From the weight of iron and aluminium phosphates, the amount of the iron, and the amount of phosphoric acid left in solution, the quantities of iron, aluminium, and phosphoric acid in the original solution can be calculated. The addition of the sodium hydroxide should be accompanied by constant stirring in order to avoid local action on the phosphates, the latter being readily acted on by alkaline solutions, losing a part of their phosphoric acid. The total phosphoric acid in solution need not exceed twice the quantity needed to combine with the iron and aluminium. w. P. s. Loss of Carbon Dioxide during Solution of Steel in Potassium Cupric Chloride. E. P. Moore and J. W. Bain. (Journ. SOC. Chem. Ind., 1908, 27, 845- &&)-The authors determined the carbon volatilised during the solution of 3 grams of steel in 200 C.C.of acid potassium cupric chloride solution by leading the gases evolved over red-hot cupric oxide, and measuring the carbon dioxide produced. The solution used was obtained by dissolving 300 grams of the double salt in one litre of water and adding 75 C.C. of concentrated hydrochloric acid; solution of the steel was effected at a temperature of 65" C. With a steel apparently containing 0.653 per cent. of carbon, four determinations showed that 0.03 to 0.06 per cent. of carbon had been volatilised, whilst with a steel apparently containing 1-18 per cent. of carbon 0.03 to 0.04 per cent. of carbon had been lost. A. G. L. New Method for the Analysis of Bronze, Brass, and Similar Alloys.E. Schurmann and H. Arnold. (Chem. Zeit., 1908, 32, 886-887.)-0ne gram of the alloy and 5 C.C. of a 50 per cent. solution of tartaric acid are placed in a 150-C.C. beaker; 4 C.C. of nitric acid (specific gravity, 1.4) are then gradually added, withTHE ANALYST. 439 constant shaking and cooling ; to the clear solution 7 C.C. of nitric acid and 80 to 90 C.C. of water are added, and the copper is deposited electrolytically, usicg Frary’s apparatus (QNALYST, 1908, 30), on a gauze cathode of 50 sq. cm. surface, with a current of 1.5 amperes at 4 volts; the electrolyte is kept cold by oirculating water through a test-tube around which the wire anode is wound, and which is immersed in the liquid; lead may be deposited on the anode, but dissolves again on standing.At the end of the electrolysis, which requires one hour, the liquid is made alkaline with potassium hydroxide, and lead and the trace of copper left in solution are precipitated with very dilute potassium sulphide, filtered off, and separated with sulphuric acid as usual. In the filtrate, antimony and tin are separated with oxalic acid and hydrogen sulphide. The trace of tin which may have been deposited with the copper is recovered by dissolving the latter in nitric acid. . If zinc is present, the sulphides of tin, antimony, lead, and copper are first precipitated with hydrogen sulphide in the liquid left after the electrolysis, after adding a considerable quantity of sulphuric acid. A. G. L. Separation and Estimation of Tin, Arsenic, and Antimony in Bronzes.M. Dinan. (Monit. Scicnt., 1908, 22, 600-602 ; through J o z L . ~ . SOC. Chenz. Iizd., 1908, 27, 963-964.)-Three grams of the alloy are treated with 30 C.C. of nitric acid (specific gravity, 1*4), the liquid being boiled after the action has ceased. The in- soluble residue, containing the whole of the tin, antimony, arsenic, and phosphorus, together with a little copper and lead, is washed by decantation, and then dissolved, by boiling for thirty minutes or more in a solution containing 10 grams of oxalic acid and 4 to 5 grams of ammonium oxalate; 1 C.C. of hydrochloric acid is then added, the whole diluted to 400 c.c , and a rapid stream of hydrogen sulphide passed tlirough the nearly boiling liquid for two hours. The precipitated sulphides of all the metals present, except tin, are filtered off and washed with hot water ; the filtrate is concentrated, 5 to 6 grams of oxalic acid are added, and tin is precipitated electro- lytically from the hot liquid, a current density of 1 ampdre per sq.dm. being used; in the filtrate phosphorus may be estimated as usual. From the sulphide precipitate obtained above, the sulphides of antimony and arsenic are dissolved by means of boiling potassium hydroxide solution, leaving the sulphides of copper and lead ; the filtrate is evaporated to 40 c.c., 60 C.C. of hydrochloric acid are added, and the heating is continued until hydrogen sulphide is completely expelled ; the precipitated arsenic sulphide is filtered off, washed with dilute hydrochloric acid, dissolved in potassium hydroxide solution, and converted into arsenic chloride by adding 60 C.C. of hydrochloric acid and a few grams of potassium chlorate; after boiling off the excess of chlorine, the arsenic is estimated iodometrically.I n the filtrate from the arsenic sulphide, antimony is similarly oxidised to the pentavalent state by means of hydrochloric acid and potassium chlorate, and estimated iodometrically, after boiling off chlorine and diluting to 500 to 600 C.C. Alternatively, antimony may be electro- lytically separated from arsenic by dissolving the sulphides in sodium sulphide solu- tion, adding alkali hydroxide and potassium cyanide, and electrolysing the liquid in the cold, using aslow current density. The sulphides of copper and lead obtained above are dissolved in nitric acid440 THE ANALYST.(specific gravity, 1.2); the solution is added to the filtrate from the original in- soluble, and the whole evaporated to about 15 C.C. ; 3 C.C. of a saturated solution o sodium acetate are added, and the cold solution is electrolysed, using a current of N.DlOo = 0.5 a m p h at 4 volts ; the copper is weighed on the cathode, and the lead peroxide, deposited on the anode, is dried at 180" to 200' C. and weighed. In the liquid, zinc is estimated, as usual, with sodium carbonate, after destroying ammonium salts. If iron is present in the alloy it contaminates many of the deposits, and its exact determination is complicated. A. G. L. Simple Method for the Estimation of the Halogen in Mercuric Chloride or Bromide. (ZeiLs. Anorg. Chenz., 1908, 59, 271-272.)-The mercuric chloride or bromide is dissolved in water, four times its weight of pure sodium hydroxide and an excess of hydrogen peroxide are added, and the solution is slowly heat,ed to boiling.As soon as the excess of hydrogen peroxide has been decomposed the precipitated mercury is filtered off and washed. The filtrate, which is free from mercury, is acidified with nitric acid, and the halogen estimated in the customary manner. A. G. L. M. Kohn. The Estimation of Nitrates in Bismuth Salts. W. H. Simmonds. (Chemist nizd Drzigist, 1908, 73, 108.)-Titration with a solution of indigo is recommended as a suitable method of estimating nitrates in the oxide, hydroxide, citrate, oxychloride, and phenate of bismuth. The reagent is prepared by dissolving 5 grams of indigo carmine in water, filtering, adding 50 C.C.of strong sulphuric acid to the filtrate, and making up the solution to a litre. The method cannot be used with the salicylate, tannate, or gallate of bismuth, and no satisfactory method is known for the estimation of nitrates in the last two. I n the case of the salicylate satisfactory results may be obtained by the following modification of Loof's method, which is based on the forma- tion of nitrosalicylate. From 0.2 to 0.5 gram of the salt is shaken with 5 C.C. of water, and the liquid cautiously mixed with 10 C.C. of strong sulphuric acid. The resulting crimson colour is matched with that produced under the same conditions with a definite quantity of a 0.1 per cent. solution of potassium nitrate containing 0.1 gram of sodium salicylate.Commercial samples of bismuth basic salicylate con- tained from 0 to 4 per cent. OE bismuth nitrate (BiONO,,H,O), whilst seven samples of the basic carbonate containedfrom 0 to 2.6 per cent., and three samples of citrate from 0 to 2.49 per cent. C. A. M. Electrolytic Determination of Nitric Acid. 0. L. Shinn. (Jozm. Anze~. Chenz. SOG., 1908, 30, 1378-1381.)-1n 1905 Ingham studied the electrolytic de- termination of nitric acid by reduction to ammonia, using the rotating anode and a high current density. The reduction must be performed in presence of sulphuric acid and copper sulphate, and if standard acid be employed, the ammonia formed may be estimated by back titration without the necessity of distilling. Considerable difficulty has been experienced in reproducing Ingham's results, the values generally obtained being considerably too low.The author proves that this error is due to residues of unreduced nitric acid, and that these residues escape reduction owing toTHE ANALYST, 441 the premature precipitation of the copper. This trouble may be surmounted by adding further quantities of copper sulphate during the course of the electrolysis. The rapidity of the precipitation of the copper depends on the speed of rotation of the anode, and if this be reduced to 120 revolutions per minute, complete reduction of the nitric acid may be effected with the proportions prescribed by Ingham. For obtaining good results, the voltage should be about 10 with a current of 4 to 5 amp8res.This requires that the quantity of acid present be limited to 20 to 25 C.C. of $ sulphuric acid. The only advantage to be gained by rotating the anode is that the copper comes down as an adherent deposit, in which case a second, and some- times a third quantity of copper sulphate must be added. With a stationary or slow- moving anade the copper deposit is spongy ; this does not affect the result, provided the copper deposit be not allowed to oxidise before washing out the acid solution from the dish for titration. J. F. B. Rapid Colorimetric Method for the Estimation of Small Quantities of Water-Soluble Phosphoric Acid. Pouget. (Chein. Zeit ., 1908, 32, 832.)-This method, which gives extremely accurate results for the estimation of exceedingly minute quantities of phosphoric acid depends upou the action of the molybdates of the alkaloids upon the phosphoric acid.A coloured turbidity is rapidly formed, which is stronger the greater the quantity of phosphate present. The estimation is then performed by comparison in a colorirneter with standards containing known quantities of phosphoric acid. The best reagent is strychnine molybdate, which always shows a direct proportionality between the coloration and the quantity of phosphoric acid. I n the estimations it is necessary always to maintain a, certain degree of acidity, corresponding to about 7 to 8 per cent. of nitric acid. The method is sensitive to 1 part of phosphoric acid in 12,000,000 of liquid. J. F. B. A New Method of Separating Silica and Tungstic Acid. E. Defacqz.(Bull. SOC. Chim., 1908 [iv.], 3, 892-894.)-Silica is not reduced by hydrogen at a temperature of 600" to 800" C., nor does it combine with chlorine at the same temperature. Tungstic anhydride, on the other hand, is reduced by hydrogen under the same conditions to a lower oxide, or even to the metallic state. I n the former case it readily yields oxychlorides, and in the latter case gives a hexachloride on treatment with chlorine. The mixture of silica and tungstic anhydride is heated to redness in a current of hydrogen, and when reduction is sufficiently complete the boat is introduced into a glass tube, with arrangements to condense the volatile products, and heated to redness in a current of chlorine. If the reduction with hydrogen is complete, the condensed products will consist of a mixture of tungsten hexachloride and oxytetrachloride (red needles); otherwise they will consist of a mixture of the oxytetrachloride and of yellow oxychloride. The absorption vessels containing these chlorides and oxychlorides are treated with very dilute ammonia solution, the washings united, and the tungsten estimated by one of the known methods. The boat containing the residual silica is heated in a current of air or in hydrogen to expel the chlorine, and then weighed. The silica should not darken when heated in hydrogen, and should not, after fusion with potassium bisulphate, give any of the reactions for tungsten compounds. C. A. 14.