ii. 578 ABSTRACTS OF ,CHEMICAL PAPERS. A n a l y t i c a l Chemistry. Behaviour of Platinum on Strong Ignition. D. BALARXFP (Chem. Ztg. 1922 46 573).-On heating eit'her new or carefully cleaned old platinum crucibles in a blast flame or over a powerful Teclu burner a fairly constant loss in weight of 0.6 mg. per hour was not'iced whilst the side of the crucible nearest the blast was considerably brighter than that more remote. No experiments were made however to find an explanation of the loss. A. R. P. Heavy Liquids €or the Separation of Minerals. ENRICO CLERIcr (Atti R. Accad. Lincei 1922 [v] 31 i 116-118; cf. A. 1911 ii 257).-The following three liquids useful for the mechanical separation of minerals of different densities are colourless and may be diluted and recovered Aqueous barium bromomercurat,e solution dl' 3-11 d18 3.14.Saturated aqueous thallium formate solution d10 3-31 dzo 3.40 d5* 4.10. Aqueous solution of thallium formate and thallium malonate in equal proportions dl0 4.00 d50 4.70 Thallium formate melting at 95" to a highly mobile liquid may also be used and a mixture of thallium formate and malonate in equal amounts melts below 95" and has d above 5. Fused thallium formate has d below 5 but it dissolves powdered thallium carbonate giving a liquid with d above 5. T. H. P. above 5. A New Physico-chemical Method of Volumetric Analysis applied to some Problems of Inorganic Chemistry. PAUL DUTOIT and ED. GROBET ( J . Chim. physique 1922,19,324-327).- A method is described by which solutions of acids may be titratedANALYTICAL CHEMISTRY.ii. 579 with bases using a thermumeter graduated in 1/100° as indicator. The solution to be titrated is placed in a small Dewar vessel which stands in a somewhat larger Dewar vessel a mechanical stirrer is placed in the solution and the alkali is added a t regular intervals in amounts which cause the temperature to increase by not more than 0.02". The burette is surrounded by asbestos paper and the stopcock is operated by a long pair of pincers. The number of C.C. of alkali added are plotted as abscisse and the temperature after each addition as ordinate and the points joined. It is found that the end-point is marked by a decided change of direction in the curve. Not only is this point fixed by the curve but all other points a t which a change in the nature of the reaction occurs are fixed.Thus with sulphuric acid the points corresponding with the completion of the formation of the hydrogen sulphate and the normal sulphate are both accurately shown. In the titration of phosphoric acid with sodium hydroxide the points where the formation of NaH,PO Na,HPO and Na,PO respectively is complete are well marked. In the titration of normal sodium phosphate with nitric acid the points where the formation of Na2HP0 NaH,PO and H,P04 is complete are clearly marked. The titration of the nitrates of zinc lead and magnesium by this method indicates the completion of the formation of definite basic salts and in the case of the two fbst-named metals of zincates and plumbites respectively. Titration of salts of cobalt copper and nickel with ammonia in the same way indicates the formation of the various ammonia complexes.This method yields identical results with those obtained by electrometric and electrocon- ductivity titrations and in addition it also indicates the formation of derivatives which these methods do not. J. P. S. Simple Method of Electrometric Titration in Acidimetry and Alkalimetry. PAUL FRANCIS SHARP and F. M. MACDOUGALL ( J . Amer. Chem. Xoc. 1922 44 1193-1196).-The object of the work described is the preparation of a number of constant and reproducible electrodes which are electromctrically equivalent to hydrogen electrodes dipping in solutions of various known hydrogen- ion concentrations. Such electrodes are extremely useful in cases where it is necessary to titrate a solution of an acid to an end-point which shall have a definite hydrogen-ion concentration. I n such a case the half cell containing a hydrogen electrode and the solution being titrated is connected with the electrode which has the same potential difference as the hydrogen electrode will have when the titration is completed.A solution of alkali is then run into the acid until a galvanometer indicates that the total ceI1 comparison electrode I sat. KCI I titration liquid I H,Pt has a zero E. M . F. The following are the comparison electrodes together with the potential against a normal calomel electrode and the equivalent hydrogen- ion concentration 21*-2ii. 580 ABSTRACTS OF CHEMICAL PAPERS. (12-12.5%) 9 9 ?I Y9 0.52 C.C. KI in 100 C.C.solution 11 ; E.M.F. 0.5195 = 10 4N-H 2-90 C.C. KI 100 0.5609 = 10-4.7~13 67.50 C.C. KI 100 11 0.6375 = 10-6N-H 6.14c.c. KI 100 , // 0.5786 = 10-jN-HANALYTICAL CHEMISTRY. ii. 581 Estimation of Free Chlorine and Hypochlorous Acid in Concentrated Salt Solutions. M. C. TAYLOR and C. A. GAMMAL ( J . Ind. Eng. Chem. 1922 14 632-635).-The estima- tion of free chlorine and hypochlorous acid in concentrated salt solutions which may contain either sodium hypochlorite or hydro- chloric acid is usually carried out by estimations of total " avail- able " chlorine and of free chlorine by an a.eration process. The latter however is inaccurate owing to decomposition of hypo- chlorous acid or of hypochlorite during aeration. It is now shown that the rate of the removal of the free chlorine is a linear function of the amount present a t any moment whilst when all free chlorine has been removed the rate of removal varies as the square of the amount of hypochlorous acid present.The curves obtained by plotting the rate of removal of chlorine against the total amount removed as measured by absorption in potassium iodide solution and titration with thiosulphate will therefore be two distinct lines having a point of intersection the abscissa of which is the free chlorine initially present as such. To obtain the amount of chlorine initially present as hypochlorous acid and hydrochloric acid the increase in acidity after aeration is determined by means of potassium iodideiodate solution in terms of thiosulphate solu- tion and this is equal to the actual loss of chlorine during aeration due to such reactions as HOCl+HCl+O.Estimation of the Chlorometric Degree of Bleaching Chlorides. J. ROYER (Ann. Falsif. 1922 15 146-148).- For the estimation of available chlorine in bleaching solutions the method of Poncius is recommended as being rapid and exact. It consists in titrating the solution with standard potassium iodide in the presence of sodium hydrogen carbonate. The fist reaction consists in the oxidation of the iodide to iodate but as soon as the free chlorine has been used up the next drop of iodide solution reacts with the iodate with the liberation of free iodine which is indicated by starch paste. Electrometric Titrations with Silver Nitrate. Estima- tion of Chlorides Bromides and Iodides and of Iodides in the Presence of Chlorides and Bromides.I. M. KOLTHOFF (2. anal. Chem. 1922 61 229-240).-In most cases the solubility of the silver compound indicates whether the end-point of a titration with silver nitrate solution may be ascertained electro- metrically. The method is trustworthy for chlorides iodides and bromides even in very low concentration and iodides may be titrated in ammoniacal solution in the presence of chlorides and bromides. Certain complex salts such as ferrocyanides pyro- phosphates etc. cannot be estimated by the method although with ferricyanides and thiocyanates the results obtained are accurate. The method may also be used for the estimation of cyanides chromates oxalates tartrates succinates and salic- G. F. M. W. G.ylates. w. P. s.ii. 582 ABSTRACTS OF CKEMICAL PAPERS. Estimation of Minute Amounts of Gaseous Oxygen and its Application to Respiratory Air. HOWARD M. SHEAFF ( J . BioE. Chew. 1922 52 35-50).-The method is intended mainly for use in following the oxygen consamption of plant and animal tissue under different conditions. By means of the appar- atus which is described and illustrated in the original it is stated $hat oxygen can be estimated in amounts as small as 1 x gram. The method depends on the conversion of the oxygen in the presence of nitric oxide and sodium hydroxide into sodium nitrite and the eshimation of the latter colorirnetrically by means of sulphanilic acid and a-napkthylamiiie. The Oxygen-absorption and Concentration of Pyro- gallol Solutions used in Gas Analysis.FRITZ HOFFMRNN (2. angew. Chew. 1922 35 325-328).-The absorptive powers of solutions of pyrogallol and potassium hydroxide of all proportions are tabulated in a Gibbs triangular diagram for the ternary system pyrogallol potassium hydroxide and water. A line of maximum absorptions was found t o correspond with mixtures containing pyrogallol and potassium hydroxide in the proportions 3 to 2. The field to one side of the line corresponding with a smaller proportion of the latter falls sharply in power of absorption. Thc optimum proportion is given as pyrogallol 20 part's potassium hydroxide 20 parts and water 60 parts. Rapid Estimation of Sulphur. I. LUIGI LOSANA (Giorn. Chim. I n d . L4ppZ. 1932 4 204-286).-The method here described depends on the fact that if a compound containing sulphur is heated with powdered iron in absence of air the sulphur in the residual mass is liberated completely as hydrogen sulphide on subsequent treatment with hydrochloric acid.This gas is absorbed by zinc acetate solution and the sulphide thus formed estimated by titration with iodine solution. Tests made on flowers of sulphur and on copper lead barium and cobalt sulphates gave excellent results. The method is applica,ble also to the estimation of sulphur in organic compounds but the latter must previously be heated with copper oxide or lead chromate in a porcelain crucible or if the organic compound is volatile in a narrow hard glass tube in which it is covered with a deep layer of the oxidising material [cf. J . SOC. Chern. Ind.1922 614~1. The Kleemann Modification of the Mjeldhal Process. FRANTISEK SKUTIL (Chem. Listy 1922 16 173-177).-The various methods of estimating the nitrogen of foodstuffs and manures using modifications of the Kjeldhal process are reviewed and $he advantages of the Kleemann modification (2. angew. Chem. 1921 34 625) pointed out. Results obtained by a modification of this method are found to be in satisfactory agreement with those ob- tained by the standard analytical method used in Czecho-Slovakia. This method differs from that of Kleemann in that after the addition of mercury 30% of hydrogen peroxide is added and then the E. S. H. M. T. H. P.ANALYTICAL CHEMISTRY. ii. 583 concentrated sulphuric acid slowly and with cooling. After some time the contents of the flask are heated until a deep coloration appears.Finally anhydrous potassium sulphate is added and the process completed. R. T. The Estimation of the Total Non-protein Nitrogen of Serum. Comparative Study of Trichloroacetic and Meta- phosphoric Acids as Protein Precipitants. PAUL CRISTOL (BUZZ. Xoc. Chim. Biol. 1922 4 267-271).-Higher values are obtained for total non-protein nitrogen when proteins are precipi- tated by means of metaphosphoric acid than when trichloroacetic acid is used for this purpose. This is due to the partial hydrolysis The Estimation of Non-protein Nitrogen in Blood. ERIC PONDER. (Biochem. J. 1922,16 368-369).-Blood (0.2 c.c.) is added to water (1 c.c.) and the pipette used is washed out twice each time with a further 0.2 C.C.of water. The protein is pecipi- tated with 0.2 C.C. of a 10% solution of sodium tungstate and 0.2 C.C. of 2/3N-sulphuric acid as in Polin's method for the preparation of blood filtrates. 0.5 C.C. of this filtrate is boiled very gently with 0.2 C.C. of a digestion mixture diluted 1 in 4. The digestion mixture consists of 50 C.C. of a 5% copper sulphate solution 100 C.C. of 85% phosphoric acid and 300 C.C. of pure sulphuric acid. After boiling for two minutes water is added to make the volume 3.5 c.c. and the solution is directly nesslerised and compared with a standard solution of ammonium sulphate. W. 0. K. Detection and Estimation of Nitrate Nitrogen in Urine and Serum. 0. NOLTE (2. anal. Chem. 1922 61 278-282). -The presence of nitrates may be detected by means of the diphenyl- amine reaction or by the less sensitive ferrous sulphate reaction ; the diphenylamine reaction however is obtained with oxidising substances other than nitrates. For the estimation of nitrates in urine the Schlosing-Grandeau gasometric method appears to be the most trustworthy but the nitric oxide content of the volume of Analytical Determination of Oxides of Nitrogen in Gas Mixtures.CHARLES L. BURDICK (J. Ind. Eng. Chern 1922 14 308-310) .-Mixtures of nitrogen peroxide and nitric oxide are absorbed in dilute alkali in a'ccordance wjth the equations 3NO,+ 2NaOH=2NaN03 +NO +H20 and NO +NO2 +2NaOH=2NaNOq+ H,O. If previous to absorption there is a development of mist in consequence of cooling t'he nitrogen peroxide present in the hot gas will be partly converted into nitric acid and nitric oxide.An absorption apparatus must therefore provide for the measure- ment of nitric oxide passing through the alkali unabsorbed. The absorption bulb in the apparatus described is a tube containing it number of glass bells with side perforations placed vertically above one another and with the inlet tube passing down through of the proteins by the former reagent. E. S. gas obtained must be estimated subsequently. w. P. s.ii. 584 ABSTRACTS OF CHEMICAL PAPERS their central axes. This is filled with a known volume of lVll0 alkali hydroxide free from carbonate diluted as required. The gas passes through this into an aspirator in which it is treated with hydrogen peroxide absorbed in excess of alkali hydroxide and estimated as usual.The solution in the absorption bulb is titrated with N/lO-sulphuric acid using a few drops of a solution of methyl-red in N/lOO-alkali hydroxide as indicator. To the neutralised solution a known excess of permanganate with 5 C.C. of sulphuric acid are added the solution is left for a few minutes a slight excess of ferrous sulphate added and the excess titrated back. If there is no acid mist present and if A C.C. of alkali and P C.C. of permanganate are neutralised in the absorber it will be seen that of this (3A +P)/2 c.c of alkali hydroxide have been neutral- ised by nitrogen peroxide and the total alkali hydroxide- (3A +P)/2 C.C. by nitric oxide. If nitric acid mist is present it is absorbed as nitrate in the bulb and is measured by the excess of alkali hydroxide neutralised over the nitrite formed whilst the nitrite formed contains twice the quantity oE nitrogen present as nitrogen peroxide.If more than 5% of excess oxygen is present in the gas mixture a correction for oxidation during the passage of the gas through the sampling A Possible Source of Error in the Bell-Doisy Method for the Estimation of Phosphates in Blood Plasma. W. DENIS and L. VON MEYSENBUG (J. BioZ. Chem. 1922 52 1-3).- The method of Bell and Doisy (A. 1920 ii 769) for the estimation of phosphates in blood gives accurate results when applied to serum but low values are obtained when plasma is used. Serum should therefore be used for this estimatjion ; if however plasma is used the accuracy may be increased by restricting the amount of ant'i-coagulant and increasing the quantities of molybdic acid and quinol.E. S. Microchemical Investigation of Arsenic. ARNALDO PIUT~T and EKRICO BOGGIO-LERA (Allem. Accad. Lincei 1922 [v] 13 475-479).-1n the detection of arsenic in very small proportions good results are obtained by using a reagent composed of 1 C.C. of 30/ ammonium molybdate solution 10 C.C. of 3.4% ammonium nitrate solution and 39 C.C. of 40% nitric acid solution. With liquids containing 0-02--0.004 mg. of arsenic per c.c. this reagent is used directly but for lower concentrations of arsenic %he reagent is diluted five times with 40% nitric acid. A drop of tlhe arsenic solution yields characteristic mict oscopic crystals when evaporated with a drop of the reagent. As little as 0*00005 mg of arsenic is detectable in this way.Estimation of Arsenic Acid. L. ROBENTHALER (2. and. Chem. 1922 61 222-229). -Diffused light does not interfere in the iodometric estimation of arsenic acid but atmospheric oxygen tube should be applied. c. I. T. H. P.ANALYTICAL CHEMISTRY. ii. 585 reacts with the hydriodic acid formed yielding further quantities of free iodine. This may be prevented by adding 5 grams of sodium hydrogen carbonate before the potassium iodide is introduced. The titration solution should cont'ain a t least 16o/b of hydrochloric acid or 33.3% of sulpburic acid. When sulphuric acid is used the follow- ing procedure should be adopted. The iodate solution is treated with concentrated sulphuric acid in quantity sufficient to make the concentration of the latter 33-37; the mixture is cooled and 5 grams of sodium hydrogen carbonate are added in small quanti- ties a t a time ; concentratled potassium iodide solution is now- added and the iodine is titrated with &-/lO-thiosulphate solution.A precipitate which forms on t'he addition of the iodide consists chiefly of arsenic tri-iodide and should be dissolved by adding a small quantity of water before the titration is commenced w. P. s. Iodometric Estimation of Arseniczand Antimony Sul- phides. FERDINAND NIKOLAI (2. anal.. Chem. 1922 61 257-272).-Arsenites and the corresponding antimony salts may be estimated volumetrically by adding their solutions to an excess of standard iodine solution containing dilute acetic acid and sodium acetate and then titrating the excess of iodine with thiosulphate solution Arsenic trisulphide or antimony trisulphide a a y be titrated by dissolving it in sodium hydroxide solution and adding this solution to iodine solution containing acetic acid and sodium acetate with subsequent titration of the excess of iodine.The alkaline solution of the sulphide is oxidised readily by atmospheric oxygen but this may be prevented or the rate of oxidation retarded to a considerable extent by the addition of a small quantity of gelatin. w. P. 8. Tests of an Iodine Pentoxide Indicator for Carbon Monoxide. S. H. KATZ and J. J. BLOOMFIELD ( J . Ind. Eng. Chem. 1922 14 30&306).-The " Hoolamite " carbon monoxide indi- cator consists of a glass tube containing granulated pumice impreg- nated with 1 part of iodine pentoxide to 5 parts of fuming sulphuric acid (60% SO,).The gas is drawn through cotton-wool filters and a tube of activated charcoal into a rubber hand bulb and discharged through the tube containing the pumice. The colour produced on the latter is matched with a series of permanent colours in a sealed glass tube. A series of tests with a large number of observers showed that by this instrument a minimum concentration of 0.07% of carbon monoxide can be detected and that a rough quantitative estimation of higher concentrations can be made. In the absence of the activated charcoal most hydrocarbons hydrogen sulphide and hydrogen chloride interfere ; methane chlorine carbon dioxide sulphur dioxide and some other gases do not. The " Hoolamite " tube may be used for six to eight estimations after which it deteriorates.c. I.ii. 586 ABSTRACTS OF CHEMICAL PAPERS. The Direct Estimation of Small Quantities of Radium by the Penetrating Rays. B. SZILARD (Compt. rend. 1922,174 1695-1698) .-The electrometer previously described (ibid. 1922 174,1618) has been modified so as to provide a transportable instru- ment working without either a high tension battery or a projection mirror. By means of it rapid measurements can be made of the penetrating rays. The sensitiveness of the instrument corresponds with U.E.S. w. @. Ash-alkalinity (of Foodstuffs). B. PFYL. (2. Unters. 1Yahr. Genussm. 1922 43 313-339).-To utilise the titration values of the ash of foodstuffs as indications of their composition it is necessary to choose the values to be determined in such a way that they are definite and as independent as possible of chance circumstances and to employ simple and unexceptionable methods for determining them.The chemical processes taking place during the incineration of foodstuffs have to be considered more closely than has been done in the past and the necessity for avoiding loss of mineral acids and for the conversion of the whole of the phosphorus into tribasic phosphate must be kept in view. In many cases this can only be attained by the addition of a measured quantity of alkali before incineration. The most useful values to be deter- mined are (a) the intrinsic alkalinity ( b ) the methyl-orange alka- linity and (c) the total phosphate of the ash. The firs6 may be defined as the excess expressed in milli-equivalents of the lrations Na.KO Ca’. Mg** which remains after combination with the anions PQ4/” SO;’ C1’ for 0”. and the weakly acid anions GO;’ SiO,” RO,’ Mn03/’ XnO4/’ A10,”. If such excess does not exist the difference is expressed as “ intrinsic acidity.” (b) is the excess expressed in milli-equivalents of the same four kations which remains after combination with the anions H,PO,’ SO4/’ and Cl’ for 0” and the above enumerated weakly acid anions. The absence of such excess is indicated as methyl-orange acidity. (c) The total phosphates is expressed in milli-equivalents of P04/”. These three values can be obtained by titration against methyl- orange followed by a titration against phenolphthalein. Full details of simple methods of carrying out the above determinations are given ; these are the result of many years of experience and are founded on sound scientific principles.Modifications necessary in special cases and precautions and corrections t o be applied where special accuracy is needed are also indicated. The above three values are usually calculated to 100 grams of dry food-stuff or 1 litre of liquid but occasionally to 1 gram of ash or 1 gram of ash soluble in hydrochloric acid. In cases of adulterat’ion one or other of these values is affected. Methods proposed by others for the determination and presentation of ash-alkalinity are criticised. Atkinson’s Process for the Estimation of Potassium in the Presence of Sodium Magnesium Sulphates and Phosphates. S. J. WATSON (Analyst 1922,47 285-288).-The H. C.R.ANALYTICAL CHEMISTRY. ii. 587 process is considered unsatisfactory because the compensating errors necessary to overcome the loss due to the solution of some potassium perchlorate do not occur to an extent sufficient to balance this loss and the quantity of methyl alcohol and perchloric acid used is too large to make the process economical. Keeping the contents of the beaker at the boiling point for an hour whilst perhaps necessary to ensure complete solution of undesirable substances mustl also favour the solution of potassium perchlorate it self. H. C. R. The Estimation of Calcium in Blood. ARTHUR ROBERT LING and JOHN HERBERT BUSHILL (Biochem. J. 1922,16 403- 406).-Two to 5 C.C. of blood are incinerated in a platinum dish treated with 1.5 C.C.of concentrated hydrochloric acid and washed into a special centrifuge tube. After adjusting the reaction the calcium is precipitated with oxalic acid and ammonium oxalate. The calcium oxalate is centrifuged and washed sulphuric acid is added and the oxalic acid titrated with permanganate. w. 0. I<. A Colorimetric Method for the Estimation of Small Amounts of Magnesium. F. S. HAMMETT and E. T. ADAMS ( J . Biol. Chem. 1922 52,211-215).-The method is designed for application to urine blood and tissue extracts and is a modifica- tion of Kramer and Tisdall’s method (A. 1921 ii 595). The pre- cipitate of ammonium magnesium phosphate obtained in the latter method is dissolved in 0-O1N-hydrochloric acid and the phosphorus estimated colorirnetrically by Bell and Doisy’s method (A.1920 ii 769). The value for magnesium is then calculated from this result E. S. Volumetric Estimation of Lead Peroxide in Miniums. Practical Modification of Diehl’s Method. A. BONIS (Ann. Falsi. 1922 15 157-159).-The following modified pro- cedure for Diehl’s method of estimating lead peroxide in samples of minium is advocated. Half a gram of the sample is macerated with 2.5 C.C. of nitric acid (d 1.080) and the mixture is washed into a conical flask with 25 C.C. of a saturated solution of sodium acetate. To this is added 10 C.C. of a 12% solution of potassium iodide in saturated sodium acetate and the whole is well shaken and the iodine liberated is titrated with N/10-thiosulphate solution. If the sample of minium contains iron oxide instead of titrating the free iodine an excess of standard thiosulphate is added and the whole is made up to 100 C.C. with the saturated sodium acetate solution.After filtering an aliquot portion of the filtrate is titrated back with N/lO-iodine solution. W. G. Rapid Electro-analysis. A. KLING and A. LASSIEUR (Ann. Chim. Analyt. 1922 4 171-177) .-For the rapid electrolytic deposition of copper or zinc a silver cathode is recommended,ii. 588 ABSTRACTS OF CHEMICAL PBPERS. together with an anode of platinum alloyed with iridium or rhodium. The silver cathode is readily cleaned without loss in weight by immersion in a cold solution of 10 grams of trichloroacetic acid in 50 C.C. of strong ammonia and 50 C.C. of water. Copper is deposited from a sulphate solution acidified with nitric acid and containing 5 grams of sodium metaphosphate if iron is present.Zinc is deposited from a solution containing sodium acetate and 5 C.C. of acetic acid per 100 c.c. together with 10 C.C. of a saturated solution of sodium fluoride if iron is present; large quantities of iron should however be separated. Lead may be deposited on the anode as peroxide from a solution containing 15 C.C. of nitric acid per 100 c.c. or as metal on the cathode by electrolysing a t 70" with 5 amperes a solution containing less than 0.4 gram of lead and 3 C.C. of nitric acid (d 1*3) 2.5 grams of crystallised gallic acid and 5 C.C. of 95% alcohol in 100 C.C. total bulk. Antimony may be electrolysed from a solution containing 80 C.C. of sodium sulphide solution (d 1-14)) 60 C.C.of water and 5 grams of potassium cyanide by a current of 5 amperes a t 60-70° or from a boiling solution containing 20 C.C. of hydrochloric acid and 4 grams of hydroxylamine hydrochloride in 130 C.C. of water. The latter solution with the addition of 10 grams of ammonium oxalate may be used for the deposition of tin. The above methods are adapted to the rapid analysis of brasses bronzes and white metals [cf. J . SOC. Chem. Ind. 1922 551~1. Iodometric Estimation of Copper in the Presence of Iron. A. WOBER (2. angew. Chem. 1922 35 336-337).-Solutions con- taining copper salts in the presence of ferrous iron always contain a small amount of cuprous ions. These cannot be oxidised by nitric acid or hydrogen peroxide in ammoniacal solution as the small amount of nitrites formed interferes with the subsequent titration.The solution is therefore made ammoniacal and treated with a current of air a t 70° whereby all the copper dissolves as cupric salt and the iron is precipitated as ferric hydroxide which is collected re-dissolved and re-precipitated to recover the ad- sorbed copper. The combined filtrate is boiled to expel ammonia acidified treated with potassium iodide and titrated as usual [cf. J . Soc. Chem. Ind. 1922 545~1. Separation of Aluminium from Iron by means of o-Phenetidine. K. CHALUPNY and K. BREISCH (2. angew. Chem. 1922,35 233-234).-The solution containing the iron and aluminium salts is slightly acidified with hydrochloric acid and treated with a current of hydrogen sulphide for ten minutes; carbon dioxide is then passed through the solution until all excess of hydrogen sulphide has been expelled.These operations are carried out in a flask closed with a cork and provided with inlet and outlet tubes. Ammonium carbonate is then added until a precipitate forms the latter is dissolved by the addition of dilute hydrochloric acid and an excess of 5% alcoholic phenetidine A. R. P. A. R. P.ANALYTICAL CHEMIS!I'RS. fi. 589 solution is added. The flask is closed the contents are heated at 80° and the precipitate is then collected washed with hot dilute ammonium nitrate solution ignited and weighed as aluminum oxide. If copper and other metals are present with the iron and aluminium the copper must be separated electrolytically the iron and aluminium then precipitated as basic acetates the latter dissolved in dilute hydrochloric acid and the solution used for the separation of the iron and aluminium as described. It is essential that the iron should be present in the ferrous state; ferric salts w.P. s. Gravimetric Analysis. XXV. Estimation of Man- ganese. L. W. WIKKLER (2. angew. Chem. 1922,35,234-235; cf. A. 1921 ii 656).-The manganese is preoipitated as manganese ammonium phosphate the method being that described pre- viously (Zoc. cit.) for the estimation of cadmium. Small corrections are applied to the weight of precipitate obtained; for instance 1 mg. is deducted when the precipitate weighs 0.2 to 0.3 gram. The presence of potassium chloride does not interfere but sodium Oxidation of Manganese to Permanganate in Alkaline Solution.J. HESLINGA (Chem. TVeekbZad 1922 19 274).- Manganese in ores and alloys is readily detected by heating the solution with potassium hydroxide and excess of copper sulphate (which acts as a catalyst) and adding a few drops of a mixture of bromine water and potassium hydroxide ; the violet coloration due to permanganate develops a t once. 0.005 Mg. of manganese may be detected. The reaction is not suitable for quantitative estima- tion since it is only complete where very small quantities of manganese are present; also the presence of iron affects the colour probably by formation of potassium ferrate. The catalytic action of the copper oxide is probably due to its tendency to form easily dissociated oxygen compounds and its tendency to form compounds with manganese hydroxide.More copper than manganese must be present otherwise the catalyst remains in this combination. The Adsorption of Iron by Precipitates of Manganese Dioxide. MAX GELOSO (Compt. rend. 1922 174 1629-1631 ; cf. Nicolardot Geloso and Rkglade A. 1920 ii 334).-When manganese is precipitated as its dioxide by the addition of ammonium persulphate to an acid solution of manganese sulphate containing some iron salt the amount of iron adsorbed by the precipitate varies directly with the amounts of iron and manganese present in the solution and inversely with the acidity. The presence of ammonium sulphate has no effect. The iron adsorbed is mostly in the form of hydroxide. Estimation of Chromium in Steels. LUIGI LOSANA and ENRICO CARGZZI (Giorn.Chim. Ind. Appl. 1922 4 197-200).- Gravimetric methods for estimating chromium in steel giye good yield a precipitate with phenetidine solution. chloride must not be present. w. P. s. s. I. L. IT. G.ii. 590 ABSTRACTS OF CHEMICAL PAPERS. results but are too tedious for industrial use and colorimetric met,hods are not to be recommended. Providedthat attention is directed to various points satisfactory results are obtained by Stead's method in which the chromium is oxidised by means of nitric acid and by permanganate to chromic acid and t'his is treated with ferrous sulphate the excess of the latter being titrated with permanganate. Modifications are suggested which render the ammonium persulphate method more rapid and exact [cf. J . New Qualitative Test for Uranium.HAROLD D. ]QUELL ( J . Ind. Eng. Chem. 1022 34 693).-Uranium may be detected in slags or ores by preparing a nitric acid solution of the material too great an excess of'acid being avoided and adding an excess of granulated zinc. When the reaction with the arid has subsided a yellow deposit will appear on the zinc if uranium is present. Gold platinum thorium lead tungsten titanium chromium mercury and copper do not interfere with the test. Iron and vanadium only interfere if present in large quantities and in that case the spent liquid is removed and the zinc and the deposit are again treated with nitric acid. The deposit dissolves but reappears when the acid is again exhausted and vanadium and iron remain in solution. As regards the delicacy of the test in a solut'ion of pure uranyl nitrate it was possible to detect 0.88 mg.of uranium per C.C. The test is not applicable in presence of sulphuric or hydrochloric acids. The yellow deposit is apparently the hydrated trioxide UO,,BH,O. Colorimetric Estimation of Vanadium in Steel. A. KROPV (2. angeu:. Chem. 1922 35 366-367).-The steel is dissolved in a mixture of nine parts of sulphuric and one part of phosphoric acid to prevent separation of tungstic acid. The solution is oxidised first with nitric acid then with ammonium persulphate to destroy carbonaceous mat'ter and the colour pro- duced by hydrogen peroxide in this solution is matched with that produced by a known amount of vanadium pentoxide added to a solution containing approximate1 p equal amounts of chromium nickel and hydrogen peroxide [cf. J .Soc. Chem. Ind. 1922 594A.1 Rapid Detection of Bismuth in Urine and in Saliva. DOMENICO GANASSINI (Roll. Chim. Farm. 1922 61 321-326).- For the detection in urine of small proportions of bismuth which is administered in the form of sodium or potassiunl bismutho- tartrate (cf. Sazerzc and Levaditi this vol. i $9) in cases of syphilis good results are obtained by means of stannous chloride solution prepared by dissolving 10 grams of the crj-stallised salt in 10 C.C. of concentrated hydrochloric acid and heating the liquid with a few pieces of tin on a water-bath until it becomes almost clear (cf. Vanino and Treubert A. 1898 ii 461). Ten C.C. of the urine are treated with 2 C.C. of this reagent and then with 5 c.c Soc.Chem. Ind. 1922 594~1. a. IT. P. G. F. M. A. R. P.ANALYTICAL CHEMISTRY. ii. 591 of 20:4 sodium hydroxide solution and the whole is shaken. If the urine contains salts of bismuth these undergo reduction to the metal which is deposited with the precipitated calcium and magnesium phosphates and gradually colours these brown or black; in some cases also the supernatant liquid becomes brown owing to dissolution of part of the bismuth in the colloidal condi- tion. Saliva may be tested similarly. That the dark precipitate actually contains bismuth may be shown by conversion of a little of it into the vivid red bismuth rubidium iodide BiI3,2RbI,2*5H,O and microscopic examination of this. Nylander's test for dextrose (A. 1884 1433) may be used in- versely as a test for bismuth but is not so sensitive as that given above. T.H. P. Estimation of Minute Quantities of Methane. ERNST MURMANN (Oesterr. Chem.-Ztg. 1922 25 90) .-The estimation of small quantities of methane involving the absorption of the carbon dioxide derived therefrom in baryta solution has hitherto required two or more absorption flasks to ensure the complete removal of carbon dioxide from the gases owing to the short time in which the bubbles are in contact with the liquid. One ordinary Erlen- meyer flask only is sufficient however if the gases are led into the baryta solution through a capillary tube and 0-5-1.0 C.C. of 1% gelatin solution is added to the liquid so as to make a foam on the surface which increases the duration of contact of the ga'ses and the absorbent solution to a t least thirty seconds and renders absorption thereby complete.The capillary may conveniently be fixed into the flask through the st'raight arm of a T-piece fitted into a rubber stopper and the connexion made gas-tight with a piece of rubber tube. The artifice may also be useful for other cases where complete absorption of a gas by a liquid is required. G. P. M. The Estimation of Benzene in Gases. E. BERL (2. ungew. Chem. 1922 35 332).-The benzene is absorbed by carbon which is then heated a t 100-120" in n current of steam (in a sabbath). A small amount of benzene remains behind and therefore a test is made with carbon containing benzene to control the results. The burette filled with water in which the benzene is collected is provided with an overflow in such a manner that the benzene remains in the burette. This method is simpler and better than that by which the benzene is washed out of the gases with light Some New Colour Reactions of Cholesterol.LOUIS KAHLENBERG ( J . BioZ. Chem. 1982 52 217-225).-Cholesterol dissolves in arsenic trichloride to a pink solution changing to cherry-red ; isocholesterol yields a cobalt blue solution changing through violet purple and dark red to dark green; phytosterol however dissolves to a colourless solution. The colours are dis- charged by the addition of solvents such as benzene toluene and petroleum. H. M.ii. 592 ABSTRACTS OF CHEMICAL PAPERS. chloroform. The colour reactions are also obtained with hot solu- tions of arsenious oxide in concentrated hydrochloric acid but are not so permanent as with the anhydrous chloride. Coloured solutions which are not however? sufficiently characteristic to be used for distinguishing between the sterols are also obtained with certain other acid chlorides E.S. Analytical Observations on the True Blood-sugar Value in Normal and Pathological Individuals. WILHELM STEPP (Arch. expt. Path. Pharm. 1922 90 105-128).-9 series of analyses of blood-sugar was carried out in the following way the proteins were removed with phosphotungstic acid and the sugar estimated by a reduction method (that of Rertrand or Laquenne); a further amount of the filtrate was freed from phosphotungstic acid with lead acetate the excess of lead removed and the solution con- centrated; the concentrated fluid was analysed for sugar by a reduction method by fermentation and polarimetrically. The values obtained by the reduction methods on the untreated filtrate were 20% to 1 0 0 ~ o higher than those obtained on the filtrate after concentration ; the difference was greatest in cases where there was nitrogen retention and was proved to be not due to loss of sugar in the process of analysis.The agreement between the resulhe obt'ained by the three methods on the concentrated filtrate was on the whole good the polari- metric and fermentation methods giving especially close agree- ment. It is suggested that nitrogenous reducing substances are carried down in the process of removing the excess of phospho- tungstic acid and that the lower values obtained after this treat- ment represent the true concentration of sugar in the blood.C. R. H. The Inversion of Sucrose in the Alkaline Copper Solu- tion. E. CANALS (Bull. Soc. chim. 1922 [iv] 31 583-588).- Results indicate that sucrose is slowly hydrolysed during the esti- mation of reducing sugars in its presence by means of some form of Fehling's solution The actual amount of sucrose hydrolysed increases with the concentration of the sucrose with the time of heating and with the temperature a t which the liquid is kept. It is essential therefore to make a blank estimation and it is advisable to heat by immersion in a water-bath. Estimation of Humus by Oxidation with Chromic Acid. A. GEHRING (2. anal. Chem. 1922 61 273-275).-The soil is first treated with dilute sulphuric acid in a flask through which a current of air free from carbon dioxide is passed.When all carbon dioxide produced by the decomposition of carbonates has been expelled potassium dichromate is added to the flask and the mixture is heated; the carbon dioxide and other gases resulting from the oxidation of the organic matter are passed through a combustion tube containing copper oxide and lead chromate and the carbon dioxide is then absorbed in potash bulbs. W. G. W. P. S,ANALYTICAL CHEMISTRY. ii. 593 Oxidation with Mixtures of Sulphuric Acid and Chromates. L. J. SIMON (Cmpt. rend. 1922,174,1706-1708).- For the wet combustion of organic compounds by means of chromic acid the most satisfactory results are obtained by the use of con- centrated sulphuric acid and silver chromate using about 15 C.C. of the acid and 12 grams of the chromate for about 0.1 gram of substance. This oxidisina mixture may be used for the combustion of acetates or acetyl derivatives theorgtical results being obtained.W. G. Analysis of Acetic Anhydride. C. EDWARD SAGE (Perf. Essent. Oil Rec. 1922 13 172).-In the method described by Reclaire (this vol. ii 532) for the estimation of acetic anhydride the phenolphthalein used as indicator seems with certain samples to be peculiarly insensitive. The actual cause of this is obscure but the peculiarity seems to run parallel with the development of the iodoform reaction when the sample in question is tested with sodium hydroxide and iodine. The unknown impurity giving this reaction may be traced back to the original acetic acid from which the anhy- dride was prepared and it seems to be associated with faults in odour which sometimes develop in products prepared from the anhydride for example aspirin or synthetic " acetyl " perfumes.The insensitiveness of phenolphthalein above mentioned may be overcome and a sharp end-point obtained if the titration is made by adding an excess of N/2-hydroxide keeping for some time without heating until hydrolysis is complete then adding a known quantity of N/2-acid and finishing off the titration with more N/2-hydroxide. By this procedure errors due to heating under reflux will also be eliminated. G. F. M. Estimation of Fatty Acids (and Cholesterol) in Small Amounts of Blood Plasma. W. R. BLOOR K. I?. PELKAN and D. M. ALLEN ( J .Biol. Chem. 1922 52 191-205).-Bloor's method (A. 1914 ii 392) for the estimation of fatty acids in blood probably gives incorrect results owing to the different nephelo- metric values which the various fatty acids and cholesterol possess (cf. Csonka A. 1918 ii 277). To overcome this two modifications are suggested (1) the separation of cholesterol from the fatty acids and the separate estimation of the two fractions thus obtained (cf. A. 1916 ii 275) (2) the use of a standard consisting of 60% oleic and 40% palmitic acid which melts a t approximately the same temperature as the mixture obtained from blood. Using these modifications the results are accurate to within 5 yo. Estimation of Small Amounts of Lactic Acid. S. W. CLAUSEN (J. Biol. Chem. 1922 52 263-280).-The method of Furth and Charnass is slightly modified. Lactic acid is decom- posed either by acid permanganate a t 95" or by soy0 sulphuric acid a t 140" the aldehyde produced being swept into excess of sodium hydrogen sulphite.The excess of the sulphite is removed by addition of iodine the end-point being adjusted to a defmite blue E. S.ii. 684 ABSTRACTS OF CHEMICAL PAPERS. to starch. Saturated sodium hydrogen carbonate is then added until the blue coloration is just discharged and the sulphite of the aldehyde bisulphite compound titrated with standard iodine the end-point being determined by a blank control. The errors which arise when the method is applied to blood or urine may be reduced but not entirely eliminated by &st extracting the lactic acid from the protein-free filtrate by ether using a special extraction apparatus.E. S. Detection and Estimation of Oxalic Acid and its Use in Standardising Iodine and Silver Solutions. L. ROSENTELALER (2. anal. Chem. 1922 61 219-222).-1odine is liberated when potassium iodate solution is heated with the addition of a small quantity of oxalic acid; the reaction may be obtained with 3mg. of oxalic acid and permits of the detection of the latter in the presence of tartaric and malic acids which reduce the iodate much more slowly. Oxalic acid and oxalates may be estimated by heating their dilute sulphuric acid solution with an excess of standard iodate solution until all free iodine has been expelled cooling the mixture and titrating the excess of iodate with thiosulphate solution after the addition of potassium iodide.It is proposed to use sodium oxalate for the standardisation of iodine solutions and of silver nitrate solutions; in the latter case a known quantity of the oxalate is treated with a slight excess of silver nitrate solution the mixture diluted to a definite volume filtered and the excess of silver titrated in an aliquot portion of the filtrate with thio- .Oxidation of Oxalic Acid in the Absence of other Acids. J. C. WITT. ( J . Physical Chem. 1922 26 435-446).-It is shown that oxalic acid may be titrated with potassium permanganate without the addition of any other acid the oxalic acid functioning both as reducing agent and acid. The end-point is marked by the appearance of turbidity followed by a slight permanent pre- cipitate and is affected by the temperature of titration the con- centration and the presence of electrolytes.When a solution of an oxalate is titrated in the presence of sulphuric acid the colloid precipitating power of the sulphate-ion is effective in the presence of a fairly high concentration of the hydrogen-ion and hence the quantity of sulphuric acid required is much greater than the theoretical value. cyanate solution. w. P. s. J. S. G. T. Standard Method for the Estimation of Soap in Wool. INDUSTRIES (Trans. Text. Inst. 1922 13 143-149).-Traces of soap left on a woollen fabric may cause serious disturbances in dyeing and consequently may require estimation It is shown that extraction a t the boiling point with neutral absolute alcohol in a glass apparatus with ground-in joints satisfactorily removes the soaps and free fatty acids from the material.BRITISH RESEARCH ASSOCIATIOR FOR THE WOOLLEN AND WORSTED J. C. W.ANALYTICAL CHEMISTRY. ii. 595 Olive Oils and the Villavecchia Reaction. JEAN PRAX (Ann. Pubif. 1922 15 159-161).-1t has been shown previously (z’bid. 1921 14 270) that certain olive oils particularly Tunisian give a red coloration with Villavecchia’s reagent similar to that given by an olive oil adulterated with sesame oil. This abnormal reaction is not obtained if such an oil is shaken with its own volume of 9074 alcohol containing 10% of ammonia and the alcohol and ammonia then evaporated on a water-bath before applying the test. It is now shown that it is as a result of the action of the ammonia that these abnormal oils no longer give the red coloration with the Villavecchia reagent.The Orcinol Reaction with Furfuraldehyde. Applica- tion to the Colorimetric Estimation of Small Quantities of Furfuraldehyde. PAUL PLEURY and GABRIEL POIROT (Bulk. SOC. Chim. Biok. 1922 4 252-266).-For the estimation 1 C.C. of the furfuraldehyde solution and 5 C.C. of a hydrochloric acid reagent (d. 1-19 and containing about 60 mg. of ferric chloride per litre) are added successively to 4 C.C. of an orcinol reagent (1 gram of orcinol in 1600 C.C. of glacial acetic acid). The mixture is then heated for one minute on a water-bath left for half an hour a t the ordinary temperature and the blue coloration compared with that produced in a standard solution treated simultaneously in the same manner.The standard solution contains 0.1 mg. of furfuraldehyde per c.c.; that to be estimated should contain between 0.01 and 0.30 mg. A Cause of Error in the Application of the Colour Test for Acetone. ANTONIO TROISE (Ann. Chim. Analyt. 1922 4 177-178).-0n testing a sample of urine for acetone by means of ammonia and sodium nitroprusside in acetic acid (Lieben’s re- action) the characteristic violet colour was obtained although the distillate did not give the reaction. The cause of the colour was found to be the presence of istycine (1.8 dihydroxyanthraquinonc) which had been taken medicinally. A. R. P. L. KOFLER (2. Unters. Nahr. Uenussrn. 1922 43 278-287).-The usual methods of investigation do not su%ce to arrive a t the identity of a saponin when i t is not available in the pure state.The author makes use of the foaming power in addition to the hzemolytic action of saponins. The “foam number” is obtained by shaking up 10 C.C. of each of a series of solutions of different concentrations in test-tubes 16 mm. internal width for fifteen seconds and allowing them to remain for fifteen minutes. The foam number is given by the dilution in that- tube in which the foam stands 1 cm. high. The haemolytic index is determined in the usual way the details of which are specified. If the haemolytic index is divided by the foam number a quotient is obtained which is independent of the state of purity of the saponin. This quotient has a characteristic value for each of the six different saponins investigated varying W.G. E. S. Differentiation and Estimation of Saponins.fi. 596 ABSTRACTS OF CHEMICATd PAPEFLS. from zero in the case of glycyrrhizin to 10 in the case of Merck’s digitonin. By this means saponins separated from artificial lemonades by Brunner’s method (ibid. 1902 5 1197; 1908 16 165; 1912 23 566; 1914 27 192) can be readily identified and quantitatively estimated by comparing the hamolytic index and foam value obtained with those tabulated for the saponin in question. It would he possible to specify a maximum value for the “poison/foam ” quotient which should not be exceeded by the saponins used in food-stuffs. The figure 1-0 or 0.5 is suggested. H. C. R. The Defecation of Blood for the Estimation of Carbamide. AL. IONESCU (Bul. 8oc. Chim. Komania 1922 4 13-17).-The defecating agent recommended consists of a saturated aqueous solution of sodium chloride to which has been added 10% of glacial acetic acid.To the serum an equal volume of this reagent is added and the mixture is heated to boiling and filtered. The filtrate is made slightly alkaline with sodium hydroxide and the carbamide estimated in an aliquot portion by the hypobromite method. W. G . The Testing of Foodstuffs €or Vitamins. J. C. DRUMMOND and A. F. WATSON (AnaZy$f 1922 47,235-246).-Details are given of the method of cartying out physiological tests on rats for the presence of the three vitamins in foodstuffs. Young healthy rats of not more than 50 grams body weight are fed on a ration of puri- fied foodstuffs from which all traces of the vitamin to be tested for have been removed. These rations are specified for each of the three vitamins. When the rats have shown no further increment of weight for fourteen days the substance to be tested is adminis- tered in a daily ration of known weight. The method has been used to show that samples of butter vary very considerably in the amount of vitamin they contain. The amount of vitamin-B in milk depends entirely on the food of the cow. The monkey is the best animal for testing for vitamin-C but the guinea pig is generally used. Testing is rendered more difficult by the fact that the guinea pig is entirely herbivorous. The potency of the food supplement added is judged from the daily dose necessary to prevent the onset of or to cure established scurvy. The antiscorbutic value of milk is dependent on the diet of the animals. Lemon juice possesses a very much higher anti- scorbutic potency than lime juice. H. c. R. The Necessity of Checking the Quality of Sodium Tung- state used in the System of Blood Analysis. OTTO FOIJN ( J . BioZ. Chem. 1922 51 419420).-Specimens of sodium tung- state which are not alkaline to phenolphthalein contain complex tungstates. They may be made suitable for use in the author’s system of blood analysis by addition of the requisite quantity of alkali. E. S.