INORGANIC ANALYSIS 517 INORGANIC ANALYSIS. Precipitation of Aluminium Hydroxide and Separation of Aluminium and Chromium. W. Jakob. (Zeitsch. anal. Chem. 1913 52 651-657.)-The precipitation of alumina from solutions of alkali aluminate by addition of bromine is complete only when the temperature is above 60" C. and the higher the temperature of precipitation the more compact is the precipitate. If caustic alkali be added to a solution of aluminium nitrate until the precipitate at first formed redissolves the Eiolution heated to boiling and excess of bromine-water added slowly so as not to reduce the temperature the precipitate will not be gelatinous. If the mixture be boiled to expel bromine filtered and the precipitate well washed the whole of the alumina free from any trace of alkali will be recovered.The best way to transfer to a filter particles of alumina which attach themselves to a beaker is to treat the contents of the beaker with a little dilute nitric acid which effects no visible change, but loosens the alumina from the glass. Ammonia is then added in excess and the particles of alumina are washed on to the filter. For the separation of aluminium from chromium caustic alkali is added to the solution of the metals until the precipitate at first formed redissolves. Bromine-water is cautiously added to the cold solution until its green colour gives place to the yellow of a chromate solution. Chromium hydroxide may separate at first but rapidly oxidises and redissolves. Finally the solution is heated to boiling and more bromine-water added drop by drop to secure the precipitation of the alumina in a compact form.It always carries down some chromium hydroxide from which, however it can be completely freed as follows The supernatant liquid is decanted through a filter and the precipitate is boiled with water containing ammonia and ammonium nitrate transferred to the filter and washed there with water containing ammonia and ammonium nitrate. Test numbers obtained with pure solutions of aluminium nitrate and chromium chloride and others obtained in presence of 1 or 2 per cent. of zinc and magnesium are exact ; but zinc and magnesium may come down with the alumina and the method is not recommended in presence of these metals. Nor is it available in presence of sulphates or borates.G. C. J. Differentiation of Natural and Artifieial Barium Sulphate. J. Jambor. (Chem. Zeit. 1913 37 1077.)-A method of distinguishing between natural and artificial barium sulphate is based upon the greater covering power of the latter. If equal quantities of the finely powdered sulphates are mixed with equal quantities of zt dyestuff into a paste the colour of the mixture prepared from the natural product will be of a lighter colour. The test may be made approximately quantitative by comparing the colour with those of standard mixtures containing up to 10 per cent, of the respective barium sulphates the different pastes being pressed between glas 518 ABSTRACTS OF CHEMICAL PAPERS plates with paraffin wax at the edges. Since differences of 2 per cent. and more may be observed with barium sulphates of different origin the accuracy of the estimation is not greater than 5 per cent.It is noteworthy that a dyestuff mixture containing 1 per cent. of Water Blue and 0.5 per cent. of Auramine colours artificial barium sulphate violet but the natural product green and by varying the relative proportions of the two sulphates all shades between these colours may be obtained. In this way it is possible to distinguish variations of 1 per cent. C. A. M. Characteristic Reaction of Bromine. I. Guareschi. (Zeitsch. anal. Chem., 1913 52 607-616.)-The author refers to his earlier papers ( A t t i R. Accad. Sci. Torho 1912 47 696 988) and claims priority for the discovery that Schifs aldehyde reagent affords a means of detecting minute quantities of bromine in presence of much chlorine and iodine (cf.Denigds ANALYST 1912,37 581). The use of hydrogen peroxide as suggested by Denigds is unnecessary. The reagent is most conveniently employed distributed on starch-free paper ; and if this is dried between other pieces of filter-paper no free sulphur dioxide will remain and less than 0.01 mgrm. of bromine is easily detected. For detecting traces of bromide in com-mercial chlorides and iodides a considerable quantity of the substance is warmed with 8 25 per cent. solution of chromic acid and the vapours tested with filter-paper prepared 8 s described. For detecting bromine in an organic compound of which it is a constituent and not merely an accidental impurity a fraction of a milligram suffices. The reagent may be made not only from fuchsin but from fnchsin S, rosaniline acetate p-rosaniline hydrochloride or Hofmann’s violet decolorised as described by Schiff or preferably as described later by Gayon (see Denigds Zoc.tit.). Hofmann’s violet affords the most sensitive reagent but the colour used must be the original colour of Hofmann-namely trimethyl- or triethyl-pararosaniline chloride-and not methyl violet B extra which is also sold as Eofmann’s violet. The reaction depends on the formation of tetrabromo-derivatives of the dyestuff, and is readily distinguished from the reaction given by aldehydes. The latter reaction is given only in solution and the reddish-violet colour is not removed from the solution by ether. When a liquid containing the tetrabromo-dyestuffs is shaken with ether the violet-blue colour collects between the ethereal and aqueous layers.G. C. J. Volumetric Estimation of Calcium. T Doring. (Zoitsch. angew. Chem., 1913 26 478-480.)-DuprB and Muller have thrown doubt on the accuracy of the method which depends on precipitation of the calcium as oxalate and titration of the washed precipitate with permanganate (Zeitsch. angew. Chem. 1902,15 1244). According to them the results may be 2 per cent. low The author shows that quantities of calcium up to 0-1 grm. (the equivalent of 50 C.C. of permanganate) can be determined with an error not exceeding 20.1 mgrm. Larger quantities should not be taken for analysis as large precipitates are more difficult to wash and calcium oxalate is soluble to the extent of 0-5 mgrm.in 100 C.C. of water and water containing ammonium oxalate cannot be used for washing when the calcium is to be determined volumetrically. Large quantities may thus be under-estimated b INORGANIC ANALYSIS 519 0.5 per cent. Indirect estimation as usually practised leads to results which are always high usually more than 1 per cent. too high. This is due to the co-precipita-tion of ammonium oxralate with calcium oxalate. The indirect method gives fairly accurate results if the precipitate be thoroughly washed but the necessity for such washing removes the sole advantage of the indirect method-namely its greater rapidity. As it possesses the added disadvantage that two standard solutions are required it cannot be recommended for exact work. G. C. J. Cerium Dioxide as Contact Substance in Analysis by Combustion.J Bekk. (Ber. 1913 46,2574-2579.)-Cerium dioxide distributed on asbestos is an effective substitute for the platinised asbestos of Desnstedt. Asbestos is steeped in ra saturated solution of cerium nitrate dried and ignited. A 30-cm. length in the combus-tion-tube makes it possible to complete a combustion of 0.2 grm. of avolatile substance in generally less than twenty minutes from the time of beginning to heat the substance to the turning out of the flame. The catalyst does not retain halogens which may be estimated simultrtneously by placing in the forward part of the combustion-tube two tared boats containing reduced silver (Dennstedt) or better by means of rt spiral of silver gauze wrapped round with platinum wire to guard against mechanical loss of silver halide during withdrawal.Nitrogen and sulphur are retained by lead peroxide placed in the forward part of the tube as in Dennstedt’s method ; but sulphur cannot be determined simultaneously as the catalyst retains an amount which varies with the temperature of combustion. The sulphur dioxide thus retained by the catalyst does not appreciably impair its efficiency and can be expelled by prolonged and intense heating in a current of air. The catalyst is not poisoned by arsenic or by lead peroxide. After about fifty hours’ effective use the asbestos becomes reduced to a powdery codition. It is still usable but the cost of its replacement is negligible. G. C. J. Estimation of Copper by Means of Sodium Hypophosphite.J. H a d . (Zeitsch. anal. Chem. 1913 52 616-618.) - Dallimore (ANALYST 1909 34 452) described a modification of the Muthman-Mawrow method (Zeitsch. anorg. Chem., 1896 11 268) for the estimation of copper and Windisch (ANALYST 1913 75) has recommended this modified method as exact. The author shows that it is open to the same criticism as the original Muthman-Mawrow msthod which he and Soukup found (ANALYST 1911 36 302) to be dependent on approximate compensation of errors which are individually large and which may be very far from being mutually compensating. That Windisch did not find copper in all his filtrates-he found it in some-is probably due to his testing the first filtrate and not the subsequent wash-waters which alwayg contain much more copper than the first filtrate.Better results are obtained by neutralising exactly with $ sodium hydroxide using phenol-phthalein as indicator as soon as precipitation is complete followed by rapid filtration and washing. Even then the method is useless for the exact determination of copper in presence of cadmium and zinc. As a technical method for the valuation of commercial copper sulphate using large quantities as recommended by Dallimore, it may have some value. G. C. J 520 ABSTRACTS OF CHEMICAL PAPERS Estimation of Copper by Means of Sodium Hypophosphite. R. Windisch. (Zeitsch. anal. Chem. 1913 52 619-628.)-The author seeks to show that the method described by Dallimore and recommended by him is free from the objections raised by Hanus and Soukup to the original Muthman-Mawrow method (cf.preceding abstract). Pure solutions of copper sulphate were precipitated in the manner previously described and the ignited precipitates proved to be substantially pure copper oxide. The filtrates were proved to contain so little copper that the error due to incomplete precipitation is estimated as less than 0-2 per cent. but the wash-waters do not appear to have been examined (cj. preceding abstract). A sample of Merck's copper sulphate was found to contain 99-16 per cent. of CuSO;5H20 as the mean of sixty-four experiments but the individual results range from 98.76 to 99.55. G. C . J. Determination of Oxygen in Copper and Brass. T. West. ( J . Inst. Metals advance proof issued August 1913.)-Turner has shown (J. Inst. Metals 1912, 8 248) that any oxygen in brass probably exists as zinc oxide and therefore cannot be determined by the methods adopted for determining oxygen in copper ; for though the zinc oxide is reduced by hydrogen at a high temperature in the cooler portion of the combustion-tube the reverse reaction occurs.The author has had resort to reduction in a current of carbon monoxide. The method was first applied to copper, and after results had been obtained which agreed closely with those obtained by reduction in hydrogen further experiments were made with zinc oxide. When the conditions for the accurate estimation of oxygen in zinc oxide had been determined, some brasses were examined with the result that it is shown that brass of good quality contains on an average 0.002 to 0.003 per cent.of oxygen. The combustion-tube used was of clear silica and rested in the porcelain tube of an electric furnace. The carbon monoxide was generated from sodium formate and sulphuric acid and stored in a gas-holder between which and the combustion-tube were (1) a caustic potash wash-bottle (2) a tube containing solid potash (3) a heated Jena glass tube containing copper gauze (4) another potash wash-bottle (5) a sulphuric acid wash-bottle (6) another heated glass tube containing copper (7) another tube containing solid potash and (8) another sulphuric acid wash-bottle. The carbon dioxide resulting from the combustion was absorbed by potash contained in Geissler bulbs provided with a small calcium chloride tube and the train of apparatus was terminated by a guard-tube containing sulphuric acid.The temperature was con-trolled by a rheostat and measured by a thermocouple the wires of which passed between the porcelain and silica tubes. In use the boat containing the drilling is introduced into the combustion-tube and a current of carbon monoxide is passed through the apparatus until the Geissler bulbs show no change in weight in one hour. The temperature is then raised to 1,050' C. and maintained there for one and a half hours after which the electric circuit is broken the apparatus allowed to cool for thirty minutes without checking the stream of gas and the Geissler bulbs are weighed full of carbon monoxide. Experiments with zinc oxide showed that the use of too slow a gas curren INORGANIC ANALYSIB 521 might lead to results much below the truth but with three bubbles per second exact results were obtained.The method is not available for copper-zinc alloys containing tin or nickel as such alloys decompose carbon monoxide although tin alone does not do so. G. C. J. Volumetric Estimation of Fluorine. A. Greef. (Ber. 1913,46 2511-2513.) -The method depends on the fact that when sufficient ferric chloride is added to a neutral solution of an alkali fluoride the whole of the fluorine separates as a white insoluble fluoride of the type Na3FeF,. The end-point of 4 simple titration with thiocyanate as indicator is not easily seen as no intense red but only a particular shade of yellow marks it. The use of ether and alcohol gives the characteristic red colour in the ethereal layer but the end-point is only sharp when the slight solubility of the precipitate is still further repressed by large addition of sodium chloride.To 25 C.C. of a neutral solution of an alkali fluoride 20 grms. of sodium chloride and 5 C.C. of a 20 per cent. solution of potassium thiocyanate are added. The mixture is then titrated with ferric chloride solution (1 C.C. =- 0.01 grm. NaF) until a faint yellow colour appears. Alcohol (10 c.o.) and ether (10 c.c.) are then added, and the titration continued with vigorous agitation after each addition until the ethereal lager acquires a persistent red colour. Commercial sodium fluoride usually has an acid reaction and contains sodium hydrogen fluoride and sodium silicofluoride. On titration with sodium hydroxide, using phenolphthalein as indicator these compounds react as follows : NaF-HF + NaOH = 2NaF + H,O and Nrt,SiF +4NaOH = 6NaF + SiO + 2H,O.As the neutralised solution contains the whole of the fluorine as sodium fluoride, total fluorine may be estimated in the manner above described. The sodium hydrogen fluoride is determined in a separate portion of the sample as follows The substance (0.5 grm.) is dissolved together with an equal weight of potassium chloride in 25 C.C. hot water the solution cooled 20 C.C. alcohol added to render potassium silicofluoride insoluble and the sodium hydrogen fluoride titrated with & sodium hydroxide using phenolphthalein as indicator. The percentage of sodium hydrogen fluoride being known the percentage of sodium silioofluoride can be calculated from the amount of alkali required to neutralise the solution taken for the estimation of total fluorine.The following are typical results Present 0.6 grm. NaF 0.2 grm. NaF-HF, 0-2 grm. Na,SiF ; found 0.598 grm. NaF 0.201 grm. NrtF*HF 0.201 grm. Na,SiF,. G. C. J. Method of Analysing Hypochlorites. F. Ducelliez. (Ann. Chim. anal., 1913 18 345-349.)-When 'cobalt chloride is brought into contact with calcium hypo-chlorite oxygen is evolved and cobalt peroxide is precipitated ; under the conditions given below this reaction may be applied to the estimation of hypochlorites. Two grms. of the calcium hypochlorite under examination are placed in a test-tube together with 50 C.C. of boiled water ; the test-tube is closed with a rubber stoppe 522 ABSTRACTS OF CHEMICAL PAPERS carrying a delivery-tube which is connected by a length of rubber tubing with a measuring burette supported in a vessel of water.The test-tube is first held in an inclined position while a quantity of 0.05 grm. of crysta.1lised cobalt chloride is placed in it just below its mouth ; the stopper is then inserted the cobalt chloride is caused to fall into the solution and the test-tube is immersed in a boiling water-bath the evolved oxygen being collected in the burette. At the end of about thirty minutes the test-tube is cooled placed in the water in the vessel containing the burette and the volume of oxygen is read off. The volume of gas found is multiplied by 0.93 to correct for vapour pressure of water and temperature provided that the temperature of the water is 1 5 O C and to the result is added 1.2 c.c.this being the volume of oxygen absorbed by the cobalt oxide to produce cobalt peroxide The method may be spplied to alkali hypochlorites and the. results obtained agree with those found by the iodometric process. w. P. s. New Method fop the Determination of the Concentration of Hydroxyl Ions. F. Francis and F. H. Geake. (J. Chm. SOC. 1913 103 1722-1734.)-The rate of decomposition of nitrosotriacetonamine into nitrogen and phorone under the action of alkalis affords a measure of the concentration of hydroxyl ions. The velocity constants have been established in presence of aqueous solutions of sodium, potassium and barium hydroxides and found to be proportional not to the concen-trations of the bases themselves but to the concentration of hydroxyl ions.In any individual experiment the values of the velocity constant agree to within 1 to 2 per cent. and the results are reproducible to within 2 to 3 per cent. The method is available with this degree of accuracy for the estimation of the concentration of hydroxyl ions up to 0.05 N and the general formula may be expressed aa follows : Concentration of OH’ = K:t./R where R = 1.96 x 2.20 10 Kt- is tho observed con-stant at the temperature to. Between concentrations of 0.05 Nand 0.3 N hydroxyl ion the unimolecular oonstanta ‘‘ drift,” and the method is inapplicable within these limite. The drift ceases a t the latter concentration ; from that point up to a concen-tration of 1.4 N the accuracy is diminished and beyond that considerably dimin-ished since the velocity constants change only slightly with large increases in the concentration of the hydroxyl ions near the higher limits.The effeot of the presence of neutral salts in moderate quantities is unimportant. to-30, J. F. B. Valuation of Hydrated Oxide of Iron by Means of the *‘Sulphuretted Hydrogen Burette.” E. Linder. (Forty-ninth Annual Report on Alkali etc., Works Proceedings during 1912 pub. 1913 20-26.)-The method consists in treat-ing a small weighed quantity of air-dried and moistened oxide (0.6 to 1 grm. oxide containing 15 to 20 per cent. moisture) with excess of eulphuretted hydrogen. The oxide is contained in a small glass cup floating on the surface of mercury in a ( 6 laboratory vessel ” (the bell-shaped piece of apparatus so called by designers of apparatus for exact gas analysis).The eulphuretted hydrogen is measured in a burette over mercury. To eliminate air from the upper part of the laboratory vessel the cup is made as small as possible and its neck constricted to follow th INORGANIC ANALYSIS 523 ourvature of the upper part of the laboratory,vessel into which it can in consequence rise. The body of air is further reduced by causing the mercury to rise in the annulus between the cup and the walls of the laboratory vessel as far as a mark on the neck of the Iabter. By this means the working space is reduced to about 15 c.c., and the air in this space ie displaced by hydrogen before the sulphuretted hydrogen is admitted. By thus working with a constant volume of an inert gas in the laboratory vessel the contraction that ensues during the sulphiding of the oxide is made an exact measure of the weight of sulphur absorbed as temperature and pressure corrections for 16 C.C.of gas are insignificant in comparison with the large volume (150 to 200 c.c.) of sulphuretted hydrogen absorbed by the oxide and can easily be caloulated and allowed for if desired, The sulphuretted hydrogen burette is water-jacketed and is partly of wide, partly of narrow bore so that any quantity of gas from 140 to 250 C.C. can be measured accurately to within 0.1 C.C. The rest of the apparatus includes levelling slide rising table and generators for hydrogen and hydrogen sulphide and is fully illustrated in the original which also describes the method of operation including the determination of the gas space above the mercury in the laboratory vessel, determination of a correction factor for the solubility of hydrogen sulphide in the water originally present and that produced during the sulphiding operation and analysis of the residual gas when this is necessary as with oxides containing carbonates.The merits of this method are best considered by reference to a standard method, such as that described in Lunge and Keane’s “Technical Methods of Chemical Analysis,” vol. ii. part ii. p. 772. The advantage of the method there described lies in the fact that a large weight of material can be operated on. But air is not effectually excluded and no account is taken of carbon dioxide which is freely liberated from some oxides and lost in the residual gases.Moreover that method is not well suited for determining the maximum efficiency of oxides which absorb sulphuretted hydrogen over a period of six or seven days. I n purifiers which remain undisturbed for many days the bottom layers of oxide are in contact with gas for prolonged periods and a measure of the maximum efficiency attained on exhaustive exposure in a desideratum. A gravimetric method with apparatus involving many parts and neceesitating disconnection for weighing from time to time is less con-venient than the volumetric method now desoribed and finally the use of dry air at the end of an experiment to displace residual gases is inadmissible in exact analysis. G. a. J. Detection of Molybdenum. E Kedesdy.(Mitt Eaisert. Materiatprafungs-Amt Gross-Lichterfelde West 1913 31 173 ; through Chem. Zentralbl. 1913 II., 996.)-The detection of molybdenum by means of potassium t hiocyanate is recom-mended by Treadwell (Kurzes Lehrbuch der analyt. Chem.) who states that there is no reaction with acid molybdate solutions but on addition of zinc or stannous chloride a blood-red coloration of molybdenum thiocyanate is produced even if phosphoric acid is present which distinguishes molybdenum from iron. The molybdenum thiocymate is taken up by ether on shaking. As hexavalen 524 ABSTRACTS OF CHEMICAL PAPERS molybdenum does not give the reaction it is better to effect reduction before carrying out the reaction and also when the valency of the molybdenum is un-known. The reduction is also necessary in order to convert any ferric compounds to ferrous since phosphoric acid or pbosphate not only checks the reaction of thiocyanate with iron but also with molybdenum.If the reduction is carried too far the reaction may fail altogether or be much weakened. Commercial ether usually contains peroxide which would cause the reoxidation of small quantities of ferrous to ferric iron. In carrying out the reaction iron should be as far as possible excluded over-reduction of the molybdenum avoided and ether freshly distilled from stannous chloride alone used. 0. E. M. Action of an Excess of a Soluble Ferrocyanide on Solutions of Zinc, Copper and Nickel and a Volumetric Method for the Estimation of Nickel. R. Meurice. (Ann. Chirn. anal. 1913 18 342-345.)-Zinc salts when treated with an excess of potassium ferrocyanide yield a definite compound having the com-position Zn,K,[Fe(CN),I, and the reaction may be employed for the volumetric estimation of this metal.The zinc solution is treated with an excess of potassium ferrocyanide solution diluted to a definite volume the precipitate is allowed to settle and an aliquot portion of the clear supernatant liquid is titrated with potassium permanganate solution after the addition of sulphuric acid. The ferrocyanide solution is standardised against the permanganate solution and this in turn against pure iron. I n the case of copper the ferrocyanide precipitate varies in composition with the concentration of the solutions and is moreover slightly soluble 80 the above method cannot be applied to the estimation of copper.Nickel however, yields a precipitate having the composition NiK(,Fe( CN), but only under certain conditions-namely in the presence of an excess of ferrocyanide and of ammonium sulphate. For the estimation of nickel the solution containing about 0.1 grm. of the metal is treated with 100 C.C. of a 3.5 per cent. potassium ferrocyanide solution, 5 grms. of ammonium sulphate are added the mixture is diluted to 200 c.c. filtered, and an aliquot portion of the filtrate is diluted with seven times its volume of water, acidified with sulphuric acid and titrated with permanganate solution One atom of iron is equivalent to 1 atom of nickel. w. P. s. Separation of Palladium from Gold Platinum Rhodium and Iridium. M. Wunder and V.Thuringer. (Zeitsch. anal. Chern. 1913 52 660-664.)-Palladium and gold can be separated from the other metals o€ the platinum group, except platinum itself by precipitation from weak (1 per cent.) hydrochloric acid solution by means of dimethylglyoxime. The reagent is dissolved in boiling water and added to the boiling solution which is maintained in ebullition for Home time, and then allowed to cool. The precipitate is collected on a hardened filter and washed with 1 per cent. hydrochloric acid. The filter and its contents are then cautiously incinerated (cf. ANALYST 1913 79) and the residue finally heated strongly with a blowpipe flame. The metal sponge is dissolved in a few drops of aqua regia and the solution repeatedly evaporated to dryness with hydrochloric acid.The residue is dissolved in water 1 to 2 grms. ammonium oxalate are added and the mixtur INORGANIC ANALYSIS 525 digested at 60' C. for some hours. Dilute sulphuric acid (10 to 15 c.c.) is added to assist filtration and the gold is filtered off on a hardened filter washed first with water containing sulphuric acid then with 1 per cent. hydrochloric acid dried and ignited. The filtrate is nearly neutralised with ammonia and the palladium re-precipitated by means of dimethylglyoxime. After cautious incineration of the filter-Paper the palladium is reduced in hydrogen and allowed to cool in a current of carbon dioxide. Platinum must be separated as ammonium platinic-chloride before palladium is precipitated by means of dimethylglyoxime. The neutral solution is concentrated t o small bulk saturated with ammonium chloride and left for two days.The precipitate is washed with a saturated solution of ammonium chloride dried the filter cautiously incinerated the residue strongly ignited at first with access of air, then in a current of hydrogen and finally cooled in a current of carbon dioxide. The palladium is determined in the filtrate in the manner already described. Palladium is separated from rhodium by precipitation with dimethylglyoxime. The rhodium in the filtrate is determined as follows The filtrate is concentrated to small bulk hydrochloric acid and a pinch of sodium chlorate are added and the mixture heated until chlorine is expelled. This destroys the dimethylglyoxime which might interfere with the subsequent reduction of the rhodium.The solution is diluted and the rhodium reduced by repeated addition of small pieces of magnesium. When the solution is colourless and all magnesium apparently dissolved the rhodium is filtered off washed with 5 per cent. sulphuric acid to remove traces of magnesium ignited, reduced in hydrogen and cooled in a current of carbon dioxide. The separation of palladium from iridium and subsequent determination of the iridium is carried out in an exactly similar manner the destruction of the dimethylglyoxime in this case being absolutely necessary G. C. J. Quantitative Volatilisation and Separation of Phosphoric Acid from the Metals of the Copper Group and from Aluminium Tin and the Alkali Metals. P. Jannasch and R. Leiste. ( J .f. prakt. Chem. 1913 88 129 ; through Chem. Zentralbl. 1913 II. 994.)-.In continuation of previous work (ANALYST 1909, 34 507) it was found that the volatilisation of the phosphoric acid may be repre-sented thus : 1. P,O + 2cc1 = 2POC1 + COCI + co,. 2. 2P,O + 3CC1 = 4POCJ3 + 3c0,. 3. MuPO + 2CCl,= MeCI + POCJ + COCI + CO,. While the secondary splitting up of the carbon tetrachloride takes place thus : and 4. 2CC1 = C,CI + 2C12, 5. 2CCl = C2C1 + C1,. I n all reactions at a high temperature free chlorine and hexachloroethane were formed but not at temperatures below a red heat. The quantitative decomposition of a phosphate thus due to carbon tetrachloride alone is hindered by the presence of chlorine t o remove which a new method involving the use of intermittent currents -was employed; this also prevents the regeneration of phosphoric acid in th 526 ABSTRACTS OF CHEMICAL PAPERS distillation-tube.The following conditions were found necessary for the complete separation of phosphoric acid from the bases (1) The use of an asbestos plug to hold back the metallic chloride; (2) the use of a diluting agent such as quartz powder to prevent the substance from fusing together; (3) complete absence of moisture. The methods and apparatus used for the separation of phosphoric acid from copper silver lead cadmium mercury bismuth aluminium tin and the alkali metals by means of the stream of carbon tetrachloride are described in detail. The addition of quartz powder renders the method applicable to phosphates of the alkaline earth and alkali metals and the ammonium sulphide and hydrogen sulphide groups.Aluminium and tin however require the addition of potassium chloride also. 0. E. M. Estimation of Phosphoric Acid SolubIe in Citric Acid in Thomas Slag. M. Popp. (Chem. Zeit. 1913 37 1085-10S7.)-It has been proposed previously (cf. ANALYST 1913 171) in the estimPtion of phosphoric acid in Thomas slag to prevent the interfering action of dissolved silica by the addition of ferric chloride, hydrogen peroxide being also added in order to oxidise any hydrogen sulphide which may be present and the aulhor now gives details of a method embodying these principles. Fifty C.C. of the citric acid extract of the slag are treated with 25 C.C. of iron-ammonium citrate solution and 1 C.C. of 3 per cent.hydrogen peroxide ; more o€ the latter must be added if the mixture is still dark in colour owing to the presence of unoxidised ferrous sulphide. Twenty-five C.C. o€ magnesia mixture are then added and the estimation is continued in the usual way. The iron-ammonium citrate solution is prepared by mixing 1 kilo of citric acid with 30 grms. of ferric chloride dissolved in 50 C.C. of water adding 4 litres of 20 per cent. ammonia and, when solution is effected diluting the whole with water to 5 litres. The results are usually within 0.3 per cent. of those found when the silica has been removed by w. P. s. means of hydrochloric acid. Volumetrie Estimation of Phosphorus in Steel by Maeagno’s Method. H. Wdowiszewski. (Chem. Zeit. 1913 37 1069-1071.)-Macagno (Gazzetta 1874, 4 467) proposed to estimate phosphorus by reducing the phosphomolybdate pre-cipitate by means of zinc in sulphuric acid solution and titrating the resulting molybdenum sesquioxide with permauganate.As modified by Emmerton (Zeitsch. anal. Chem. 1892 31 71) who concluded that the final product of reduction by zinc was M O ~ ~ O ~ ~ and not Mo,O, the method is given in many textbooks-for example, in Blair’s ‘‘ Chemical Analysis of Iron.” The method as described by Blair gives rise to results which may be 100 per cent. too high but are more commonly from 10 to 30 per cent. too low. The author finds that it is essential to success to wash the phosphomolybdate precipitate with water after washing it with dilute nitric acid, as otherwise ammonium nitrate will pass into solution when the precipitate is dissolved in ammonia and this nitrate will be reduced by the zinc to nitrite which may double the consumption of permanganate in the final titretion.The time allowed by Blair (ten minutes) and others for reduction is much too short but molybdic acid can be reduced to Mo,O by zinc. On the other hand the reduce INORGANIC ANALYSIS 527 eolution is so rapidly oxidised beyond the stage of the hypothetical Mo,,019 that accurate results cannot be obtained by any method involving filtration from un-dissolved zinc or direct titration with permanganate. By decanting from the zinc into a measured and more than sufficient volume of standard permanganate and titrating back with oxalic acid excellent results can be obtained. The phosphomolybdate precipitate obtained in any manner which ensures its having a P20, MOO ratio closely approximating 1 24 is freed from iron by washing with 1 per cent.nitric acid and from nitric acid by washing with water. The filter is set in the neck of the 300 C.C. conical flask used for precipitation, the precipitate dissolved in a little 4 per cent,. ammonia and the filter washed with hot water until the contents of the flask amount to about 30 C.C. From 80 to 100 C.C. dilute (1 4) sulphuric acid and 10 grms. zinc are added and the mixture is maintained just short of ebullition for forty-five to fifty minutes which is only about fifteen minutes longer than is absolutely necessary. I t is then removed from the hot-plate and the clear liquid immediately decanted into another flask containing a measured volume of standard permanganate.The flask and zinc are rinsed with hot 10 per cent. sulphuric acid which is also decanted into the flask containing the permanganate and the excess of permanganate is titrated with an oxalic solution of equivalent strength. The test numbers agree well with those obtained on large quantities of steel by the use with every precaution of the gravimetric (magnesia) method and still more closely with results obtained on the same steels by the alkalimetric method. A single determination cannot be completed in much less than two hours from weighing the drillings but several can be conducted simultaneously. G. C. J. Estimation of Cobalt and Uranium in Steel. H. Konig. (Chew. Zeit., 1913 37 1106-1107.)-The method for the determination of cobalt depends on the electrode position of cobalt nickel and iron from an ammonium oxalate electrolyte, the separate estimation of iron and nickel and calculation of cobalt by difference.The metallic deposit after being weighed is used for the determination of iron as follows I t is dissolved in hot dilute sulphuric acid and nickel sulphate solution is added cautiously until its green colour just predominates over the pink due to cobalt. The iron can then be titrated with permanganate as usual. Contrary to the state-ments of Brunck (Stahl. u. Eisen 1908 331) and others nickel cannot be separated from cobalt by means of dimethylglyoxime. In steels containing nickel and cobalt, the former can be determined as follows Tungstic acid is separated as usual by means of a p a regia most of the iron removed from the solution by shaking with ether dissolved ether is boiled away the solution reduced by means of sulphurous acid the excess of the latter boiled away and the solution neutralised with potassium hydroxide.When cool potassium cyanide solution is added whereby nickel cobalt, and iron go into solution but chromium is precipitated. The mixture is made up to 200 c.c. mixed filtered and 100 C.C. taken for the estimation of nickel. This 100 C.C. is boiled whereby the potassium cobaltocyanide is transformed for the most part into cobalticyanide which is not precipitated by potassium hydroxide and bromine water. Addition of bromine water to the cooled solution completes this transforma 528 ABSTRACTS OF CHEMICAL PAPERS tion and precipitates the nickel as hydroxide.The nickel hydroxide is filtered off, washed dissolved in dilute hydrochloric acid chlorine expelled by boiling and the nickel precipitated by means of dimethylglyoxime. For the concentration of small quantities of uranium from solutions containing much iron advantage is taken of the fact that uranium is not deposited from an ammonium oxalate electrolyte. The steel is treated with aqua regia to separate tungsten chlorides are decomposed by evaporation with sulphuric acid and the iron is deposited electrolytically after neutralisation of excess of acid by ammonia and addition of ammonium oxslate. After the iron has been deposited the electrolysis is continued to destroy ammonium oxalate.The solution usually acquires a yellow colour due to formation of chromate and a precipitate containing uranium as well as chromium manganese and vanadium and a trace of iron may separate. The solution is boiled down to one-third of its bulk to destroy ammonium carbonate, which results from the decomposition of the oxalate and the precipitate containing all the uranium together with more or less chromium aluminium manganese iron, and vanadium is filtered off and washed with a dilute solution of ammonium chloride. It is then dissolved in dilute hydrochloric acid any chromic acid present is reduced by addition of a few drops of alcohol and the solution boiled with a little nitric acid and transferred to a small flask in which it is cooled. To the cold liquid, excess of ammonium carbonate and ammonium sulphide are added and the flask is corked and set aside for twelve hours.Iron chromium manganese and aluminium are thus precipitated and in the filtrate uranium is separated from vanadium by acidifying with acetic acid and heating to boiling when vanadium comes down a8 sulphide. The filtrate from the vanadium is reoxidised by boiling with nitric acid, uranium is precipitated by means of ammonia the precipitate washed with dilute ammonium chloride and the uranium finally weighed as U,O, or as UO,. The author prefers to ignite the precipitate in a Rose crucible in a current of hydrogen and weigh as UO,. G. C. J. Preparing Sections of Fractures of Steel for Microscopic Examination. A. Campion and J. M. Ferguson. (J. Iron and Steel Inst.1913 Advance Proof.) -In investigations relating to the breakdown of metals an examination of the fracture or of a section through the fracture is often of importance. The preparation of sections of fractures for microscopical examination especially of soft and ductile materials presents considerable difficulty as during the polishing operations the edges of the fracture become rounded or worn away. I n order to overcome this difficulty Roeenhain embedded the fracture in copper by electro-deposition and then cut through the copper and steel in the desired direction. The method is excellent, but requires much attention and considerable time for the deposition of Q inch of .copper. The authors find that satisfactory results may be obtained by embedding the fractured end of a test bar in a suitable fusible alloy cutting a section and polishing.Of several alloys tried the following was found the best for general work: Bismuth 50 lead 30 tin 25 zinc 3 ; m.-pt. below 100" C. This alloy readily penetrates the minute fissures in the fracture is hard enough to support the edges of the fracture during polishing and adheres strongly to the specimen. The fracture INORGANIC AhT-tQLYSIS 529 test-piece is dipped momentarily into dilute (1 1) hydrochloric acid then into similar acid which has been ‘‘ killed ” by zinc and finally into the alloy a little above its melting-point. If the alloy freezes the test-piece is held in position until it melts again. It is then allowed to cool still holding the test-piece until solidification takes place.When cold sections are cut by means of a fine saw and the specimen polished in the usual manner. A section can be prepared and a photograph obtained within half an hour of the breaking test. G. C. J. Rapid Estimation of Sulphur in Burned Pyrites. L. Sznajder. (C7zenz. Zeit. 1913 37 1107.)-2-5 grms. of the finely divided material is mixed with about 1 grm. sodium carbonate and 4 grrns. zinc oxide in a spun iron crucible and kept a t The cooled contents of the crucible are transferred to a 250 C.C. flask with hot water the flask is filled to the mark and its contents are shaken and filtered. Two hundred C.C. of the filtrate is heated to boiling and exactly neutralised to phenolphthalein by addition of dilute hydrochloric acid to the boiling solution.Thirty C.C. of barium chloride solution are added whilst main-taining violent agitation of the liquid and the excess of barium chloride is then titrated with I n spite of the presence of the precipitate the first appearance of a pink tinge is readily recognised after a little practice. The method gives results about 1 per cent. higher than those obtained gravimetrically, but on material with only 2 to 3 per cent. of sulphur this is negligible. red heat €or thirty minutes. sodium carbonate. G. C. J. Quantitative Precipitation of Tungstic Acid by Means of Aromatic Amines. E. Kafka. (Zeitsch. anal. Chenz. 1913 52 601-606.)-1t is known that tungstic acid can be precipitated by means of benzidine and a-naphthylamine (v. Knorre Ber. 1905 38 783; Tschilikin Ber.1909 42 1302). The author now shows that cumidine tetramethylparadiaminodiphenylmethane and tetramethyl-diaminobenzophenone can be used for the purpose. The reagents are prepared as follows Cumidine (5 grms.) is mixed with 10 C.C. water and dissolved by addition of 5 C.C. concentrated hydrochloric acid or 6 grms. tetramethyldiaminodiphenylmethane is dissolved in 4 C.C. hydrochloric acid or 7-5 grms. recrystallised tetramethyldiamino-benzophenone is dissolved in 10 C.C. hydrochloric acid and the solutions are diluted to 100 C.C. As the precipitates are somewhat soluble in water but much less so in dilute solutions of the reagents they are washed with a solution made by diluting 5 C.C. of the reagent to 100 C.C. To 50 C.C. of a solution containing about 0.2 grm.tttngstic acid as sodium tungstate 10 to 15 C.C. of the reagent is added with constant stirring. The mixture is stirred from time to time during an hour at the end of which time the precipitate is filtered off washed ignited in a platinum crucible without previous drying and weighed as WO,. Test numbers obtained with solutions of pure sodium tungstate are accurate within *O-8 per cent. The precipitates cannot be dried without partial decomposition but analysis of such dried precipitates leaves no doubt that the original precipitate in the case of tetramethyldiaminodiphenyl-methane has the composition WO,.CI7H2?N2 and in the case of tetramethyldiamino-benzophenone 2W0,.3C,7H,oN,0. G. C. J 530 ABSTRACTS OF CHEMICAL PAPERS Action of Various Waters on Lead. H. Heap.(J. SOC. Chem. Ind. 1913, 32 771-775 811-815 847-856.)-Experiments were made by a modification of Frank-land's lead-pipe method and by a method,depending on the use of pure lead foil. At an early stage in the research it was found that lead pipes could not be used continuously for a series of comparable experiments with different waters. Once they had acquired a protective coating from one water they resisted the action of other water which would have attacked clean lead the protective coating gradually dissolves in a corrosive water with the result that corrosion is slow at first and then accelerates. The disadvantages of using new lead pipe for each experiment are obvious and fortunately it was found that such experiments gave results in close agreement with those made by the foil method which was consequently adopted in all the later work.The foil (0.012 cm. thick) waR polished brightly with wash-leather and cut into strips 6.35 by 2-54 cms. In each experiment one of these strips was placed in a specially constructed glass vessel entirely filled with the water to be tested. The vessels were cylindrical in shape held about 120 c.c. and were fitted with broad conical stoppers so that by filling the vessel with water and inserting the stopper, water was displaced until the stopper fitted tightly. I n experiments made at temperatures far removed from room-temperature the water in the bottle was allowed to reach the temperature of the thermostat and the foil and stopper then inserted. In some experiments the water was placed under anaerobic conditions.The gases were pumped off by making use of Adeney's gas analysis apparatus which offers the further advantage that various gases can be introduced at definite pressures to the gas-free water. The most important conclusion reached is that oxygen is the most potent factor in the solution of lead. Whereas distilled water free from gases only dissolved 0.01 part per 100,000 in twenty-four hours at 24" C. and water under 1 atm. pressure of carbon dioxide 1-6 part water under 1 atm. pressure of oxygen dissolved 12 parts. Of all the salts tried only ammonium nitrate had a solvent action of the same order as oxygen and ammonium nitrate has to be present in a concentration approximating 25 parts per 100,000 before it is as corrosive as distilled water saturated with oxygen.The function of carbon dioxide is a secondary but important one. In absence of carbon dioxide the action of oxygen ceases when the water is saturated with lead hydroxide but in the simultaneous presence of carbon dioxide the lead is precipitated as carbonate or basic carbonate and the action is continuous so long as any oxygen remains in solution. This is the mechanism of the familiar phenomenon known as the '' erosion " of lead. Waters containing the carbonates or bicarbonates of the alkali or alkaline earth metals give rise to a protective coating of lead carbonate after the formation of which no more lead dissolves. If a phosphate is present so little lead dissolves before the formation of a protective coating that it can only be detected by refined methods On the other hand calcium sulphate affords no protection and water containing calcium sulphate but no bicarbonate attacks lead vigorously.G. C. J INORGANIC ANALYSIS 531 Estimation of Lithium in Mineral Waters. L. W. Winkler. (Zeitsch. anal. Chenz. 1913 52 628-640.)-Isobutyl alcohol affords an excellent means of separating lithium chloride from the chlorides of sodium and potassium and is much less objectionable to work with than amyl alcohol which was recommended by Gooch. At room temperature 10 C.C. isobutyl alcohol dissolve only 0.5 mgrm. of potassium and sodium chloride whereas amyl alcohol dissolves twice as much. From quantities of alkali chloride not exceeding 1 grm. the lithium may be separated as follows The mixed chlorides are dried at 130' C.and when cold are extracted with successive small quantities of isobutyl alcohol (about 2 C.C. each time) delivered from a measuring cylinder and the extracts decanted through a 4 cm. filter into a platinum crucible. About 10 C.C. of the alcohol should be used in all and the amount measured. The filtrate is evaporated to dryness the residue dissolved in a few drops of water about five times its weight of ammonium sulphate added the mixture dried on the water-bath and then in an oven the temperature of which is gradually raised until at about 180" C. the contents of the crucible begin to emit fumes. The covered crucible is then heated over a small flame which is subse-quently raised until an incipient red heat is attained. The cover is removed once or twice until no further fumes are seen and the crucible and lithium sulphate are then allowed to cool in the air and weighed.From the increase in weight of the crucible 0.5 mgrm. is deducted to correct for the solubility of the chlorides of sodium and potassium. I n this way approximately 90 per cent. of the lithium is recovered. The residue from the treatment with isobutyl alcohol is dissolved in water the solution acidified with hydrochloric acid evaporated to dryness dried at 120" C., re-extracted with isobutyl alcohol as before the residue is dissolved as before and the whole series of operations repeated a third time. The quantity of lithium sulphate obtained from the third extraction after correcting for the solubility of sodium and potassium chloride is usually of the order of 0.1 mgrm.The chlorides of calcium magnesium and aluminium are soluble in isobutyl alcohol and must be absent from any saline residue submitted to the process. The process as described can be applied to the mixture of alkali chlorides obtained in the ordinary course of a water analysis but lithium will usually be under-estimated if lime salts have been eliminated in the usual manner. In a water with 100 degrees of hardness approximately 10 per cent. of the lithium will be co-precipitated with the calcium as carbonate and in a water of 10 degrees of hard-ness about 1 per cent. of the lithium will be lost. I t is better to determine lithium in a separate portion of the sample. If the water has more than 100 degrees of hardness it is first diluted.Waters less hard are not concentrated but treated with excess of alkali hydroxide and carbonate to precipitate magnesium and calcium. A litre of the water is treated with these reagents heated on the water-bath for an hour allowed to cool filtered and the residue washed with water containing a little alkali carbonate and hydroxide. If the lime-hardness exceeds 10 degrees the pre-cipitate is dissolved in hydrochloric acid the solution evaporated to dryness the residue redissolved in a Iitre of water and calcium and magnesium reprecipitated as before The united filtrates are acidified with hydrochloric acid treated with excess of barium chloride and a little nitric acid (to destroy organic matter) and evaporate 532 ABSTRACTS OF CHEMICAL PAPERS to a pasty consistency.The lithium is next separated from the greater part of the other alkali chlorides present by treating the pasty mass with five times its own weight of absolute alcohol which is decanted off through a filter. The residue is redissolved in water the solution acidified with hydrochloric acid evaporated to a paste and the paste extracted with alcohol as before. The residue is again dissolved and the series of operations repeated. The alcoholic filtrates are united, diluted with an equal bulk of water and evaporated to dryness. The residue is dis-solved in water acidulated with hydrochloric acid and the solution usually cloudy, is filtered and evaporated to dryness. The saline residue is freed from the last traces of calcium and magnesium by solution in 10 to 20 C.C.water treatment with a few drops of a solution of alkali hydroxide and carbonate and filtration washing with a dilute solution of the precipitant. The filtrate is acidified with hydrochloric acid evaporated to dryness and the residue redissolved in 10 to 20 C.C. water. The last trace of aluminium is eliminated by addition of a few drops of ammonia heating to boiling allowing to stand an hour and filtration washing with water contailaing a few drops of ammonia. A few drops of alkali hydroxide solution are added to the filtrate which is next evaporated to half bulk to expel ammonia as ammonium chloride increases the solubility of potassium and sodium chlorides in isobutyl alcohol. Finally the solution is acidified with hydrochloric acid evaporated to dryness and the saline residue dried at 120" C.Usually it will weigh less than 1 grm. and the lithium is then separated as described in the opening paragraph; but if much more than 1 grm. the lithium should first be concentrated by treatment with alcohoI. A single extraction with ten times its weight of alcohol and filtration through a plug of cotton-wool suffices at this stage. G. C. J. Hydrolytic Action a Source of Error in the Estimation of Iodine and Bromine in Mineral Waters etc. P. Kaschinsky. (Zeitsch. angew. Chem. 1913, 26 492-494.)-Owing to the dissociation of magnesium halides according to the equation MgX + 2H,O = Mg(OH) + 2HX the whole of the iodine and almost all the bromine present as iodides and bromides in a mineral water may be lost when the water is evaporated and the residue ignited.I t is essential that the magnesium salts be removed by precipitation with alkali hydroxide and subsequent filtration before the iodine and bromine are estimated. Potassium hydroxide is to be preferred to calcium hydroxide for the precipitation of the magnesium saltp as potassium chloride is less soluble than calcium chloride in the alcohol which is used in the process. w. P. s. Estimation of Small Quantities of Hydrogen Sulphide in Natural Waters. L. W. Winkler. (Zeitsch. anaZ. Chem. 1913 52 641-645.)-The reagent employed for producing the coloration the intensiiy of which is made the measure of the hydrogen sulphide present is a solution of 10 grms. Rochelle salt 10 grms. ammonium chloride and 0.1 grm. lead acetate in 100 C.C.of 5 per cent. ammonia. The Rochelle salt and ammonium chloride prevent the precipitation of calcium carbonate and the hydroxides of magnesium and iron and Rochelle salt also prevents the development of any interfering colour due to iron sulphide. The standard solution used for makin INORGANIC ANALYSIS 533 the colour comparison is an approximately 0.1 per cent. solution of sodium sulphide, Ne2S.9H,0 a salt which can now be obtained (from Kahlbaurn) substantially pure. Whereas a dilute solution of sodium sulphide in distilled water suffers a loss of titer of 35 per cent or more in twenty-four hours a solution made up with a 50 per cent. solution of sodium nitrate instead of water loses its titer at less than one-third of this rate. Such a solution has been found useful but it should be used as soon after preparation as possible.A completely satisfactory deiiermination of hydrogen sulphide in water can only be made at the source. The sodium sulphide is best conveyed to the point of collection of the sample as follows About 0.1 grm. is accurately weighed into a weighing-bottle of not more than 1 C.C. capacity. The stopper is then greased bhe bottle taken to the place of collection and its contents dissolved in 100 C.C. of sodium nitrate solution rendered feebly alkaline with ammonia. The water to be examined is collected in a bottle of known volume (about 100 c.c.) 5 C.C. of the lead reagent is added the stopper inserted and the contents shaken and then transferred to a 200 C.C. beaker. In a second beaker 100 C.C. of distilled water and 5 C.C. of the lead reagent are mixed and standard sodium sulphide solution is run in from a burette until the tint matches that of the sample under examination. If the water to be examined is naturally coloured the influence of this colour may be corrected for as follows Some of the water is treated with the lead reagent placed in a stoppered bottle which it should only half fill and shaken at intervals for an hour or two. The lead sulphide at first formed is thus oxidised and the resulting solution identical with the original water in colour and free from hydrogen sulphide, is then used instead of distilled water for the preparation of the standard of com-parison. G. C. J