ANALYTICAL CHEMISTRY.IN addition to the application of chemical reactions to qualitativeand quantitative work, the period under review has furnished somedefinite advances in the utilisation of physical methods for analyticalpurposes. The magneto-optic method (Paraday effect) has not,so far as we are aware, been applied hitherto to the detection ofkations. It has, of course, been utilised for investigations ofoptical rotation in the magnetic field, but the paper by F. Allisonand E. J. Murphy points out a method of test equal to the mostdelicate of the methods now available. As is well known, theFaraday effect consists in the rotation of the plane of polarisation oflight on passing through a liquid, when this is placed in a magneticfield, and it has been supposed that this effect followed immediatelyon the application of the magnetic field.Allison and his co-workershave produced evidence in favour of a time-lag between the Faradayeffect and the magnetic field, the time-lag being utilised for thedetection of kations. This is accomplished by using two liquid cellsof equal dimensions, so arranged that the alternating electricimpulse obtained by means of a high-potential spark between metalelectrodes is divided in the electric circuit, so that the opticalrotation due to the magnetic field produced in the solenoid woundround the observation cells is in opposite directions. The arrange-ment of apparatus is such t'hat light, plane polarised through aNicol prism, passes through the first cell, then traverses the air spaceto the second cell and passes through this cell, which is followed byanother Nicol prism originally crossed so as to extinguish the lightfrom the first prism.Since there is an air gap between the two cells,the light takes a short time (Le., the distance between the cell centresin cm. divided by 3 x lolo, the velocity of light) to reach the secondcell. The length of the circuit to the winding around the second cellis therefore vaned, by means of movable contacts, so that theelectric impulse reaches this solenoid in the time equal to that takenfor the light to traverse the distance between the centres of the twocells. In the case where the same liquid is used in both cells, nolight will pass through the second crossed Nicol with this arrange-ment of apparatus.Carbon disulphide is chosen as a standard towhich other liquids are referred, since it shows the smallest time-lagJ . Amer. Chern. h'oc., 1930,52,3796; A., 1641204 ELLIS AND FOX:between the Faraday effect and the magnetic field, and the apparatusis adjusted to zero position with both cells containing this liquid. Ifnow, one cell is filled with another liquid, say carbon tetrachloride,it is found that in order to extinguish the light, or to obtain a sharpminimum of light passing through the second Nicol, it is necessaryto move the cell back, or else to alter the length of the electriccircuit, which effects the same purpose. The distance through whichthe cell is moved or the alteration in length of the circuit divided bythe velocity of light gives a value for the time-lag of the liquidreferred to carbon disulphide as a standard.It was found that eachcompound, organic or inorganic, has its own time-lag and thusproduces a minimum of light at a point characteristic of the com-pound. Further, in a mixture, each compound retains its owntime-lag. Each kation has its own minimum or several minimawhich appear to depend on the number of isotopes. The chloridesare best adapted for investigation, since the minima are separatedfarthest in these compounds. An unexpected result of this inquirywas that compounds retained their characteristic minima until theconcentration was reduced below 1 in 1O1O, whereupon the minimafaded out. The apparatus has to be calibrated for the kation beingsought for, and when this is done it seems to be available for deter-mining solubilities of slightly soluble salts, or for mixtures.Examplesof the extent of the time-lags referred to carbon disulphide are thefollowing : zinc chloride (four isotopes) - 6-08, -6.40, - 6.73, and- 6-85 x 10-9 sec. ; lead chloride (four) - 21.90, - 22-07, - 22.30,and - 22-68 x 10-9 sec. As the tirne-lags could be determinedwithin 0-2 x sec. on different occasions, and were much closerfor any individual set of experiments, the method appears capable ofwide application.The use of X-rays in quantitative chemical analysis is now takingshape more definitely as a practical means of technical analysis forgeneral laboratory use.Chemical and spectroscopic methods oftest depend upon the outer electrons of the atom, while X-rayspectra which utilise the K and L electrons lend themselves especiallyto “atomic ” analysis by reason of the simplicity of the spectracompared with optical spectra. The X-ray spectra themselves areunequivocal for the element, since the K-line suspected to belong toan element need only be accepted if the whole series of K-lines of thatelement is present. This gives a check on the method at once, andit differs from the optical spectral method which depends in the limiton persistent spectral lines. has utilised both the Kand L spectra for the detection of impurities in zinc, and is able, ingeneral, to identify metallic elements from chromium (at.no. 24)2 T. H. Laby, Trans. Faraday Soc., 1930,26,497; A., 1141.T. H. LabANALYTICAL CHEMISTRY. 205upwards. He has in this way discovered minute traces of impuritiessuch as gallium, germanium, molybdenum , and tungsten, presentin quantities which would escape detection by chemical methods asordinarily applied to the analysis of spelter. It is pointed out byLaby that the advantages of the method are that one photographof the X-ray spectrum gives all the elements from chromium touranium, that analysis of chemically similar elements such as therare earths is more easily carried nut, and that the specimen is notconsumed in the examination. A communication3 on the applic-ation of X-ray spectroscopy to quantitative analysis demonstratesthat certain alloys of copper and zinc, tin and cadmium, lead andbismuth, and so on, may be analysed with an accuracy of 0.5% of theconstituent, provided the metals are those of close atomic numbers.Another X-ray method for quantitative analysis utilises secondaryX-rays4 and a special form of tube so that the substance underinvestigation is supported on a screen, but is separated from thehigh vacuum of the tube itself by means of a thin aluminium sheet.An anticathode giving harder radiation than the edges of the absorp-tion band of the element undergoing examination is used to producethe secondary radiation and this is compared with the lines furnishedby a standard substance known to be present in definite amount.Atable is now available giving the principal comparison lines of thesecondary radiation for the elements from sodium to uranium, sothat the choice of a suitable standard substance becomes compara-tively easy.For this purpose the rare earths offer special advantages,for they are unlikely to occur in any ordinary material which is beingexamined, thus permitting of their addition in definite amountswithout introducing any error due to the sample itself containing therare earth. This method is claimed to give the proportion of anelement which is present to the extent of 1 yo or so, with an accuracyof 0.01%. A method similar to the foregoing has recently beenapplied to the determination of potassium in soils with verysuccessful results. In this case a known amount of manganese oxideis incorporated with the soil, and the proportion of potassium foundby comparing the intensity photographically of the potassium lineKu, of wave-length 3734 X.U.* with the second-order KP, line ofmanganese which appears at 3812 X.U.Of the more recent applications of the optical spectroscopicmethod, one of the most interesting deals with the determination ofcadmium, lead, and iron in zinc.6 It is shown how quantities ofC.E. Eddy and T. H. Laby, Proc. Roy. Soc., 1930, [A], 127, 20; A., 724.G. von Hevesy, J. Bohm, and A. Faessler, 2. Physik, 1930,63,74; A., 1141.J. T. Calvert, Trans. Paraday SOC., 1930, 26, 509.D. M. Smith, ibid., p. 101. * 1 X.U. = 10-l1 cm206 ELLIS AND FOX:impurities of the order of 0.001 yo can be detected and estimated witha fair degree of accuracy in a very short time.The method employseither arc or spark spectra obtained with electrodes of the metalbeing tested under carefully controlled conditions ; the impurity isestimated by comparing visually on the spectrogram, the intensityof a fixed line of the impurity with that of a near-by line due to thezinc itself. Tables are given showing the most suitable lines forexamination. Thus, cadmium line A 2144.4 is compared with zincline A 2147.4, and this enables one to estimate the cadmium whenpresent in proportions from 0-1 to 0.001 yo. Similarly, lead and ironmay be determined within certain limits imposed by considerationsof the accuracy of determining intensities of lines on photographicplates. A variation of the method is that employing an '' auxiliary "spectrum of some other metal.' Thus, in the determination ofcadmium in zinc, there is superimposed on the zinc spectrum aspect,rum derived from pure tin electrodes, and the slit of thespectrograph is shortened so that short tin lines are readily recogniseddistributed amongst the longer zinc lines.Pairs of cadmium andtin lines are then chosen of equal intensity and compared with atable showing for different proportions of cadmium in zinc whichlines show equal intensity on the photographic plate. The use of amethod such as that described enables large numbers of specimensof zinc to be tested rapidly for the impurities mentioned and for anyothers for which calibration can be effected in a similar manner.Itis to be noted that the methods described above give results whichare specific for particular elements, and in this respect they possess adefinite advantage over most other physical methods applied to theanalysis of mixtures, e.g., refractivity or viscosity. There is afurther advantage inasmuch as the quantity of material required issmall and is not destroyed in the test. In this respect the processeshave an advantage over purely chemical methods, but it is not to beinferred, therefore, that the advantage is wholly with the physicalmethods. These fail to be delicate enough with certain elementssuch as phosphorus or arsenic, and they are not so good as a chemicalmethod when adequate material for test is available in such casesas the determination of lead, copper, iron, nickel, when these arepresent in large or in very small proportion of the order of 0.001%.An interesting procedure for the identification of volatile organicliquids is furnished by determining the variation of the azeotropismof the binary system consisting of the substance to be identified andsome standard pure liquid.8 The deviation in azeotropism is' W.Gerlach, 2. Metallk., 1928, 20, 248; 2. anorg. Chem., 1924, 142, 387.M. Lecat, 2. physikal. Chem., 1930, 148, 232; Bull. Acad. roy. Belg., 1929,[v], 15, 1073; A., 724ANALYTICAL CHEMISTRY. 207found from the difference in boiling point of the standard liquid andof the binary azeotrope formed with it. Tables are availableshowing the limits of azeotropism for hydrocarbons, alcohols, esters,and ketones boiling from 80" to 225", and for the constants ofsuitable standard liquids.In some cases two or three binarysystems may have to be examined before the unknown liquid can beidentified, but the method is fairly rapid and requires little materialfor examination.When large numbers of determinations of halogens in organiccompounds have to be made, the ordinary Carius method, or heatingwith lime, is slow and rather cumbersome. It was shown some timeago9 that a modified Kjeldahl method using chromic oxide inaddition to sulphuric acid was capable of giving accurate results onthe determination of chlorine and bromine. A similar method, butone which is suitable for iodine as well as chlorine and bromine, hasnow been worked out: lo it has also been applied successfully to themicrochemical determination of halogens and metals l1 in organiccompounds.In this process, fuming sulphuric acid, alone or withoxidising reagents, is employed in a special form of apparatus. Forchlorine and bromine, the liberation of halogen is complete and it maybe trapped in an alkaline arsenite solution for final estimation. Withiodine it is necessary to use'hydrogen peroxide to obtain free iodine,and some iodic acid may be formed. ' This is conveniently reducedby means of hydrazine, and the hydriodic acid oxidised to iodine byhydrogen peroxide. The results given for both macro- and micro-determinations are very good. These processes are rapid andcapable of being applied readily when numerous determinationshave t o be made.A further advantage of the second procedure isthat the digestion liquid from which the halogen has been expelled isavailable for determining other elements, particularly metals, presentin the compound investigated. This is of special convenience fororganic arsenic or antimony compounds. The method is likely togive low results for selenium, for it has been shown l2 that seleniumdioxide is appreciably volatile in open vessels. For this reason amodified Carius tube method was devised for organic seleniumcompounds on the micro-scrtle and gave very satisfactory resultswhen the precipitated selenium was weighed on a Pregl micro-Goochcrucible. The process was also found suitable for tellurium, but inview of the non-volatility of tellurium dioxide, the decomposition ofP.W. Robertson, J., 1916,109,218.lo J. J. Thompson and U. 0. Oakdale, J . Amer. Chem. Soc., 1930,52, 1195;11 H. H. Willard and J. J. Thompson, ibid., p. 1893; A., 940.l2 H. D . K. Drew and C. R. Porter, J., 1930, 2091.A., 799208 ELLIS AND FOX:the telluro-organic compound can be effected in a micro-Kjeldahlflask.Of the numerous applications of the micro-chemical methods ofanalysis, some of much importance are described in " Mikrochemie,Festschrift, 1930 " dedicated to Prof. F'riedrich Emich. A prelimin-ary communication l3 deals with the micro-methods for the examin-ation of beryllium silicate rocks working on a few milligrams ofsample. No claim for completeness is made, but a definite stepforward in micro-mineral analysis is here set out, for it is shown howthe following constituents may be separated *and determined :phosphoric oxide, aluminium, iron, beryllium, and magnesium.Inthis analysis the value of 8-hydroxyquinoline as a precipitant forkations is again demonstrated.An ingenious method of applying the micro-Dumas method fornitrogen determinations, while avoiding the use of a micro-balance,is to weigh out about 0.1 g. of material, and dissolve it in a knownamount of some solvent such as carbon tetrachloride. An aliquotportion of the solution is mixed with copper oxide and the solvent isallowed to evaporate away. The impregnated copper oxide is trans-ferred to a micro-Dumas combustion apparatus and the nitrogendetermined as usual.14In all precise micro-chemical work, proper facilities, includingseparate rooms, micro-chemical balances, and the special apparatusnecessary for accurate work, are desirable, but it is not so well knownthat a good ordinary chemical balance can readily be adapted forweighings to less than 0.01 mgm.The balance selected must be ofthe kind in which the suspension hooks for the pans are supportedwholly vertically below the agate planes and knife edges, withoutbends on the portion of the support rising to the agate planes.A. E. Conrady l5 has shown that by a method of calibration andweighing fully described, which avoids swinging of the pointer,it is possible to obtain weighings with normal loads, capable of beingreproduced to less than 0.01 mgm.A simple brake arrestment forthe pointer is needed, and this is readily made and attached. Thebrake is a useful addition to any precision balance since it enables thebalance arms and pointer to be released without vibration.Amongst the papers presented to the symposium on AnalyticalChemistry l6 held in Atlanta, Ga., in April 1930, are several impor-tant reviews which give succinct accounts of some modern analyticaldevelopments. Amongst these are three subjects of increasingl3 A. Benedetti-Pichler and F. Schreider, Ernich Festschrift, 1930, 1.l4 J. B. Niederl, 0. R. Trasitz, and W. J. Saschek, ibid., pp. 219, 232.l5 PYOC. Roy. SOC., 1922, [ A ] , 101, 211.l6 Ind. Eng. Chern.(Anal.), 1930, 2,INo. 3ANALYTICAL CHEMISTRY. 209interest for analytical chemistry : (1) Applications of photo-electriccells to chemical analysis,l7 which deals briefly with the types ofphoto-electric cells and their circuits and gives indications of theirpractical use in chemical investigations involving colorimetry ;(2) a review of the progress of potentiometric titrations,18 which givesan outline of the theory, shows the types of titration apparatus,and displays in an admirable manner the various kinds of titrationsfor which potentiometric methods have been employed ; and(3) conductometric titrations,lg a short account of some practicalmethods applied t o water analysis, the determination of the acidityof fruit juices, wines, and so on.In this connexion, attention is called t o the form of capillaryelectrode2O which is suitable for determining the pPH values at apoint in plant tissues.The apparatus is a small calomel half-cellfitted to a capillary agar-potassium chloride bridge, capable of usewith quinhydrone. Since it is sufficiently compact to be movedabout readily, it can be utilised for the exploration of plant tubers.The employment of ceric sulphate as an oxidising agent in volu-metric analysis is extending, for it has the advantage of being morestable than permanganate, is more reactive in the presence of acids,and it can be used in fairly concentrated hydrochloric acid solutions.The only reaction is Ce"" to Ce"', and there are no side reactions.The solution of ceric sulphate in dilute sulphuric acid is readilystandardised potentiometrically against ferrous sulphate,21 oragainst sodium oxalate.22 Determinations may be carried out inhot solutions, but in some cases the use of iodine chloride as acatalyst enables the titration to be carried out .at lower temperatures.In such cases methylene-blue may be used as an internal indicator forvisual titrations.Further applications of ceric sulphate solutionsare now available. Thallium can be determined electrometrically inwarm hydrochloric acid solutions, the results reported being quitesati~factory.~~ Tellurous acid may also be readily determined pro-vided chromic sulphate is added as a catalyst, a reaction whichpoints to much wider applications.24 A peculiar selective degree ofoxidation of organic acids has also been discovered, for whilst formic,acetic, succinic, fumaric, and maleic acids are not oxidised by cericsulphate, tartaric, malonic, malic, glycollic, and citric acids a,re sooxidised, although some peculiarities are to be observed in theproportion of Ce"" required per mol.of organic acid.23 Again,I. M. Kolthoff, ibid., p. 225.l7 H. M. Partridge, Ind. Eng. Clzem. ( A d . ) , 1930, 2, 207.l8 N. H. Furman, ibid., p. 213.2o I. M. Robertson and A. M. Smith, J . SOC. Chem. I d . , 1930,49,120~.21 N. H. Furmen, J . Arner. Chin. Soc., 1928, 50, 755; A., 1928, 499.22 H. H. Willard and (Miss) P. Young, ibid., p. 1322; A., 1928,725.23 Idem, ibid., 1930,52, 132; A., 312. 24 Idem, ibid., p. 555; A., 443210 ELLIS AND FOX:quinol is rapidly and completely oxidised to quinone, with thepeculiarity that the electrometric titration proceeds best when thequinol solution is added to the ceric sulphate solution.25 Usefulreversible indicators for the end-point of the titration of ferroussulphate with ceric sulphate are erio-glaucin A and alkali-fast (erio)green A.26 These indicators are yellow in ferric solutions and rose-coloured in ceric solutions.A comprehensive bibliography andreference to the use of ceric sulphate up to May 1930 is to be foundin Furman’s review of potentiometric titrations referred to above.18Inorganic Analysis.Qualitative.-A mixture of hexamethylenetetramine with potass-ium iodide forms a more sensitive reagent for the microchemicaldetection of the heavy metals than “ hexamine ” alone.27 Di-phenylthiocarbazone forms coloured complex compounds with manyheavy metals,28 whilst lead, bismuth, copper, and cobalt give color-ations with viscose solution.29 Systematic spot-analysis for thecommoner metals is further developed,30 and the effect of thepresence of other elements on some microscopical tests for metals hasbeen recorded.31 A specific reaction for cadmium with nitrophenol-arsinic acid is described,32 and the action of Meurice’s bromidebrucine reagent for cadmium on other heavy metals has beenin~estigated.~~Variations of a flame test for tin are de~cribed,~* also drop re-actions for lead 35 and for the mercurous Colour reactions ofsomewhat limited value are given by resorcinol with lead,37 andwith ~ i n c .~ 8 The use of certain phenolic acids has been applied tothe detection and separation of the metals of the analytical group25 N. H. Furman and J. H. Wallace, jun., J . Anzer. Chem. SOC., 1928, 50,1443 ; A., 727.26 Idem, ibid., p. 2347 ; A., 1012.27 I. M. Korenman, Pharm. Zentr., 1929, 70,709; A., 1929,1412; compare28 H. Fischer, 2. angew. Chem., 1929,42, 1025; A., 1929, 1412.29 J. V. Tamchyna, Chem. Listy, 1930, 24, 31 ; A., 443.30 K. Heller and Z. Fleischhans, Mikrochem., 1930,8, 33 ; A., 443 ; compareK. Heller and P. Krumholz, ibid., 1929, 7, 213; A., 1929, 900.31 W. F. Whitmore and F. Schneider, ibid., 1930,8,293 ; A,, 1148.32 F. Pavelka and E. Kolmer, ibid., p. 277; A., 1147.33 I.M. Korenman, Pharm. Zentr., 1929,70, 693; A., 1929, 1413.34 E. Schroer and A. Balandin, 2. anorg. Chem., 1930, 189, 258; A., 727;H. Meissner, 2 . anal. Chem., 1930,80,247; A., 882; F. L. Hahn, ibid., 1930, 82,113.idem, ibid., p. 1; A., 1929, 286.35 F. Pavelka, Mikrochem., 1929, 7, 301; A., 182.36 N. A. Tananaev, Ukrain. Chem. J., 1930, 5, 63; A., 1148.87 Ligor Bey and M. Faillebin, Bull. SOC. chim., 1930, [iv], 47, 225; A., 663.38 K. Fabrich, Verh. Geol. Bundesanst. Wien, 1929; A., 1147ANALYTICAL CHEMISTRY. 211IIA.30 Under suitable conditions, Feigl’s rhodanine reagent forsilver is very sensitive also for mercury and copper.40 The com-pounds of nickel, copper, and cobalt with dithio-oxamide can beutilised in microchemical tests for these metals.4l Diisonitroso-acetone is a more sensitive reagent for ferrous iron than dimethyl-glyoxime ; 42 reactions of aluminium, iron, chromium, manganese,zinc, nickel, and cobalt with organic reagents are ~ummarised.~~Bismuth alone interferes with the use of caesium sulphate as confirm-atory reagent in detecting aluminium.44 A new scheme of separ-ation of the metals of the iron, zinc, barium, and alkali groups inpresence of phosphates has been de~ised.4~ The cobalt-thiocyanatereaction for the detection of these ions has been in~estigated,~~and also the composition of the precipitate obtained by the actionof ferrocyanide on zinc salts in the presence of cobalt, utilised as acolour test for The compound Cs2[Ni(Se03),], formed byreaction of caesium chloride and sodium selenite with nickelis distinguished from the similar crystals given with magnesium salts,other than phosphate, by reaction with dirnethylgly~xime.~~Rapid and trustworthy methods for the detection of the alkaline-earth metals are recommended; 5O with sodium tungstate, bariumions give characteristic 0ctahedra.5~ The bromides of calcium,strontium, and magnesium are soluble in isoamyl alcohol, whilstthose of barium, sodium, and potassium are almost insoluble.52 Fur-ther details are given of the use of p-nitrobenzeneazoresorcinol as areagent for magnesium, 53 for which thiodiphenylcarbazide has alsobeen used.54 Magnesium and lithium do not interfere with thedetection of potassium as pi~rate,5~ and further work is recorded on*O I.M. KoIthoff, J . Amer. Chem. SOC., 1930, 52, 2222; A., 1011; compare4 * F. Feigl and H. J. Kapulitzas, Mikrochem., 1930, 8, 239; A., 1147;42 J . Dubsky and M. Kurag, Chem. Listy, 1929, 23, 496 ; A., 1929, 1414.43 G. Sensi and R. Testori, Ann. Chim. Appl., 1929,19,383; A., 1929,1413.44 H. Yagoda and H. M. Partridge, J . Amer. Chem. SOC., 1930,52,3579 ; A.,45 M. 0. Charmandarjan, 2. unc-tE. Chem., 1929,79,90; A., 183.4 6 I. M. Kolthoff, Mikrochem., 1930, 8, 176; A., 882.47 A. Schachkeldian, J . Russ. Phys. Chem. SOC., 1929, 61, 2217; A,, 563.48 A. Martini, Mikrochem., 1930, 8, 41 ; A., 566.49 L. Rosenthaler, ibid., p. 151; A., 881.50 P. Agostini and R. Abbiate, Ann. Chim. Appl., 1930, 20, 229; A., 1147.51 G. Denighs, Bull.SOC. Pharm. Bordeaux, 1929,67, 4 ; A., 53.62 H. Yagoda, J . Amer. Chem. Soc., 1930, 52, 3068; A., 1264.63 E. W. EngeI, ibid., p. 1812 ; A., 881 ; H. Leitmeier and F. Feigl, Tach.64 P. Agostini, Ann. Chim. Appl., 1930, 20, 235; A., 1147.66 E. R. Caley, J . Amer. Chem. Soc., 1930,52,953; A., 562.P. N. Das-Gupta, J . Indian Chem. SOC., 1929, 6, 627; A., 1929, 1412.Ann. Reports, 1929, 26, 190.P. RBy, 2. anal. Chem., 1929,79, 94; A., 182.1393.Min. Petr. Mitt., 1930, 40, 325; A., 1264212 ELLIS AND FOX:the use of zirconium sulphate as a reagent for potassium 56 and onthe triple acetate test for sodium.57Spot-tests for vanadium and tungsten 58 and for the preciousmetals 59 are described, as also the analytical application of catalyticreactions in the platinum group.60 Silver azide is dimorphous,crystallising either in needles or in plates.61 Molybdates give colourreactions with phenylhydrazine .62 and with potassium benzyl-xanthate.63 The general analytical behaviour of ekatantalum isde~cribed.6~Some general schemes for the detection of the principal anionshave been devised,65 including methods for anions containing thecyanogen group.66 Test-papers for carbonyl chloride are preparedfrom mixed solutions of dimethyl-p-aminobenzaldehyde and di-phenylamine.67 Various methods are proposed for the detection offluorine in rocks and mineral waters.68 Reactions for nitrites aregiven by upomorphine, 69 aminosulphonic acid, 70 and aqueous extractof walnut kernels.71 A silver nitrate-tannin reagent is reduced byeven traces of ammonia.72Feigl's azide-iodide reaction is applied as a test for sulphide-sulphur in minera1s,T3 and a comparison has been drawn of the5 6 R.D. Reedand J. R. Withrow, J . Amer. Chem. SOC., 1929,51,3238; A . ,6 7 V. P. Malitzky and V. A. Tubakaiev, Mikrochem., 1929, 7, 334; A , , 181.5 8 N. A. Tananaev and G. A. Pantchenko, J . Ruas. Phys. Chem. SOC., 1929,6@ N. A. Tananaev and K. A. Dolgov, ibid., p. 1377; A., 185; H. Holzer,6o F. L. Hahn, ibid., p. 77 ; A., 445 ; F. Feigl and P. Krumholz, Ber., 193061 R. Uzel, J . Czech. Chem. Comm., 1930, 2, 300; A., 1010.62 E. Montignie, Bull. SOC. chim., 1930, [iv], 47, 128 ; A., 313.63 S. L. Malowan, 2. anal. Chem., 1929, 79, 201; A., 153.65 P. Agostini, Ann.Chim. Appl,, 1929,19, 520; A., 311; idem, ibid., 1930,2Q, 112; A., 725; F. E. Raurich, Anal. Pis. Quim., 1930,28, 749; A., 1392.66 A. Schapovalenko, Ukrain. Chem. J . , 1929,4,303; A., 313; J.Russ. Phys.C'Jzem. SOC., 1929,61,2101; A . , 562; T. Pavolini, Ann. Chim. Appl., 1929,19,561 ; A . , 444.52; idem, ibid., 1930,52,2666; A., 1150.61, 1051 ; A., 54.Mikrochem., 1930, 8, 271; A., 1160.63, [B], 1917; A., 1394.A. von Grosse, J . Amer. Chem. SOC., 1930,52, 1742 ; A . , 883.67 A. Suchier, 2. anal. Chem., 1929, 79, 183; A., 181.68 I. P. Alimarin, ibid., 1930, 81, 8 ; A., 1143 ; H. Leitmeier and F. Feigl,Tsch. Min. Petr. Mitt., 1929, 4Q,6 ; A., 51 ; J. C. Gil, Anal. Fis. Quim. (Tech.),1929, 2'7, 141 ; A . , 51.F. Pavelka, Mikrochem., 1930, 8, 46; A., 442.70 P.Baumgarten and I. Marggraff, Ber., 1930,63, [B], 1019; &4., 880.7 1 P. Zywnev, 2. anal. Chem., 1930, 79, 389; A., 442.72 K. G. Makris, ibid., 81, 212; A., 1263.meier, Tsch. Min. Petr. Mitt., 1929, 40, 20; A,, 51.M. Niessner, Mikrochern., 1930, 8, 121 ; A., 879; F. Feigl and H. LeitANALYTICAL CHEMISTRY. 213sensitivity of various tests for traces of hydrogen ~ulphide.'~ Theformation of methylene iodide from iodoacetic acid and persulphatesserves as a delicate test for these salts,75 whilst hyposulphites give arose coloration with ammoniacal naphthol-yellow.76 A colour testfor silicate depends upon the formation of a complex silico-rn~lybdate.~~Quantitative.-Dichlorofluorescein is a suitable adsorption indicatorfor the argentometric titration of very dilute chloride solutions ; 78bromophenol-blue and bromocresol-purple may be used in titratingbromides or chlorides with mercurous nitrate.79 The effect of thepresence of various kations in this method has also beeninvestigated.80The pH of the colour change of some vegetable indicators is recorded,81as also the sensitivity and stability of phthaleins and sulphone-phthaleins to alkaliYs2 and a stable, sensitive starch indicator.s3Several other papers deal with indicators.84 Some aspects of thecolorimetric pn determination are discussed.85Borax and mercuric oxideYsG sodium ~ x a l a t e , ~ ~ potassium titaniumoxalate,s8 and various other compounds 89 have been examined asstandards in volumetric analysis, and also the processes occurring inE.C. Truesdale, Id. Brig. Chm. (Anal.), 1930,2,299; A., 1144.G. Panopoulos and A. Petzetakis, Chem.-Ztg., 1930, 54, 310; A.,736.7 6 E. E. Jelley, Analyst, 1930, 55, 34; A., 181.77 F. Feigl and H. Leitmeier, Tach. Min. Petr. Mitt., 1929, 40, 1; A.,I. M. Kolthoff, W. M. Lauer, and C. J. Sunde, J. Amer. Chem. SOC., 1929,62.51,3273 ; A., 60.ID L. von Zombory, 2. anorg. Chem., 1929,184,237 ; A., 64.N. P. Rudenko, J. Ruse. Phya. Chem. SOC., 1930,62,605; A., 1010.A. del Campo, A. Rancaiio, and G. Subero, Anal. Pis. Quim., 1929, 27,687; A., 60; N. P. Sobyanin and S. G. Saakov, J . Chem. Id. Russia, 1929,6, 736; A., 1143; 0. B. Pratt and H. 0. Swartout, Science, 1930, 71, 486;A., 1142.82 A. Thiel, Monatsh., 1929, 53 and 54, 1008 ; A,, 1929, 1410.8s M.S. Nichols, Id. Eng. Chern. (And.), 1929, 1, 216; A., 1929, 1411.84 H. Eichler, 2. anal. Chem., 1929, 79, 81; A., 181; F. L. Hahn, ibid.,1930, 80, 321; A., 1009; J. F. Reith, Phurm. WeekbZad, 1929, 66, 1097;A., 181; B. Samdahl, J . Pharm. Chim., 1930, [viii], 11, 8; A., 343; E. E .Harris, H. W. Haugen, and B. E. Fahl, J . Amer. Chem. SOC., 1930, 52, 2397;A., 1009; A. H. Johnson and J. R. Green, Id. Eng. Chem. (Anal.), 1930, 2,2; A., 660.86 S. F. Acree and E. H. Fawcett, ibicE., p. 78; A., 660; L. Wolf, 2. Elektro-chem., 1930,36,803 ; A., 1391.86 N. A. Lazarkevitsch, Ukrain. Chem. J., 1929,4,405 ; A., 309 ; R. Biazzoand C. Chines, Ann. Chirn. Appl., 1930,20,258; A., 1143.U.S. Bur. Stand., 1930, Circ.381; A,, 726.W. M. Thornton, jun., and R. Roseman, Amer. J . Sei., 1930, [v], 20,Vasterling, P h m . Ztg., 1930, 75, 68 ; A., 182.14; A., 1009214 ELLIS AND FOX:thiosulphate solutions on keeping.9* The iodine monochloride end-point is used in the titration of iodide 91 and arsenite; 92 bromo-iodometric methods are given for urea, ammonium salts, formic acid,and iodides,9* and some alkalimetric titrations describedSg3 Animproved method of determining water in micas has been devised,94and also a more general process involving the use of calcium h ~ d r i d e . ~ ~The sensitivity of various colorimetric reactions of iron, nickel,copper, and silver has been ascertained by an electrochemicalmethodYg6 and the methods of indicating the sensitivity of analyticalreactions 97 and methods of indirect analysis are discu~sed.~~Aluminous silicates may be attacked by sintering with smallamounts of sodium carbonate,99 and sulphide minerals by fusion withsodium thiosulphate.1 Other papers of general interest deal withthe segregation of samples for analysis,2 with the effect of variousfactors on the separation of metals by fractional pre~ipitation,~with modern trends in analytical chemisfry,4 and with analyticalseparations by ether e~traction.~Several volumetric and colorimetric methods of determiningcopper are described, reagents in the latter class including nitroso-F.L. Hahn and H. Clos, 2. anal. Chem., 1929,79, 11 ; A , , 51 ; E. Schulek,ibid., 1930, 80, 190; A., 725; F. H. Campbell and F.J. Watson, Chem. Eng.Min. Rev., 1930, 22, 340; A . , 1144.91 E. H. Swift, J . Amer. Chem. SOC., 1930, 52, 894; A., 561.92 E. H. Swift and C. H. Gregory, ibid., p. 901; A., 561.92a J. H. vm der Meulen, Chem. Weekbkzd, 1930,27,550, 558; A . , 1392.93 C . J. van Nieuwenburg, ibid., pp, 143, 158, 186, 206; A., 879; idem,ibid., p. 174; A., 1142; W. Poethke and P. Manicke, 2. anal. Chem., 1929,79,241; A., 311; 0. Schewket, Biochem. Z., 1930, 224, 325; A . , 1392.94 I(. Wiskont and I. Alimarin, Z . anal. Chem., 1929,79,271; A . , 310.95 0. Notevarp, ibid., 1930, 80, 21 ; A., 560.96 H. Fritz, ibid., 1929, 78, 418; A., 1929, 1414.97 F. L. Hahn, Mikrochem., 1930, 8, 75 ; A., 441 ; K. Heller, ibid., p. 141 ;98 0. Liesche, 2. angew. Chem., 1929,42, 1109; A., 310; P.Fuchs, 2. anal.A. N. Finn and J. F. Klekotka, BUT. Stand. J . Res., 1930, 4, 809; A.,E. Donath, Chem.-Ztg., 1930, 54, 78; A., 311.A., 879.Chem., 1930,79, 417 ; A., 441 ; 0. Liesche, ibid., 81, 273.1010.a G. F. Smith, L. V. Hardy, and E. L. Gard, Ind. Eng. Chem. (Anal.), 1929,a 0. Ruff, Oesterr. Chem.-Ztg., 1929, 32, 199; A . , 180.1, 228; A., 1929, 1409.H. H. Willard, Ind. Eng. Chem. (Anal.), 1930,2, 201 ; A., 1142 ; L. Moser,0. von Grossmann, Chem.-Ztg., 1930,54, 402; A., 879.A. T. Kiichlh, Rec. trav. chim., 1930, 49, 151; A., 313; W. Orlik and W.Tietze, Chem.-Ztg., 1930, 54, 174; A., 444; M. Lora y Tomayo, And. Pis.Quirn., 1930, 28, 63; A., 444; J. Golse, Bull. SOC. chim., 1930, [iv], 47, 655;A., 1148.Monatsh., 1929,53 and 54, 39; A., 1929, 1410mALYTICAL CHEMX3TRY. 215chromotropic acid,' urolobin,8 sodium diethyldithi~carbamate,~and salicylate-benzidine.9" Copper may be weighed in the form ofits compound with salicylaldoximelo and as the complex[HgI,](Cu en,); 1b the precipitation of copper by boiling withthiosulphate has been critically examined,ll and a rapid method isdescribed for converting cupric into cuprous sulphide.12Precipitation of lead as sulphate yields accurate results only whenthe solution is free from ferric and potassium salts, chlorides, andbromides ; l3 the chromate method has also been investigated.14Sodium bismuthate may be evaluated by a gasometric method ; l6bismuth can be quantitatively precipitated as the complex[BiI,](Co en,)I l6 or by means of selenious acid, which also precipit-ates titanium.17Cadmium may be weighed as the hydrated oxalate l8 or as thecompound Cd12,2[(CH,),N,,C,H,]I.19Cupferron precipitates mercurous ions quantitatively from nitricacid solutions ; 2o mercuric salts are reduced to mercurous chlorideby hypophosphorous acid in presence of hydrochloric acid andhydrogen peroxide 21 or to metal by hydrazine or stannous chloride.22Studies of the Gutzeit method for arsenic have been made.23 Aniodometric determination of quinquevalent antimony is described,24E.Cherbuliez and S. Ansbacher, Helv. Chim. Acta, 1930,13, 187; A., 564.A. Emmerie, Chem. Weekblad, 1930, 2'7, 552; A., 1393.T. Callan and J. A. R. Henderson, Analyst, 1929, 54, 650; A., 53.OaA.B. Schachkeldian, J . Appl. Chem. Russia, 1929, 2, 475; A., 444.lo F. Ephraim, Ber., 1930,63, [B], 1928; A., 1393.IOU G. Spacu and G. Suciu, 8. anal. Chem., 1929, 79, 329; A., 1929, 1413.l1 J. Majdel, ibid., p, 38; A., 53.l2 F. L. Hahn, Ber., 1930, 63, [B], 1616; A., 1011.l9 Z . Karaoglanov and B. Sagortschev, 8. anal. Chem., 1930, 81, 275;l4 Z. Karaoglanov and B. Sagortschev, loc. cit.; 33. Jones, Analyst, 1930,l6 T . Somiya and K. Kawai, J . SOC. Chem. I d . Japan, 1929, 32, 2 4 9 ~ ;l6 G. Spacu and G. Suciu, 2. anal. Chern., 1929,79,196; A., 184.l7 R. Berg and M. Teitelbaum, 2. anorg. Chem., 1930,189,101 ; A., 566.l8 J. Dick, 8. anal. Chem., 1929, 78, 414; A., 1929, 1412.lo V. Evrard, Natuurwetensch. Tijds., 1929, 11, 191 ; A., 182.2o A.Pinkus and (Mlle.) M. Kntzenstein, Bull. SOC. chim. Belg., 1930, 39,A., 1393 ; Z . Karaoglanov, Ber., 1930,63, [B], 597 ; A., 563.55, 318; A., 881.A., 184.179; A,, 1011.E. Cattelain, J . Pharm. Chim., 1930, [viii], 11, 580; A., 1148.2a H. H. Willard and A. W. Boldyreff, J . Amer. Chem. SOC., 1930, 52, 569;A., 444 ; Jean, Bull. SOC. Pharm. Bordeaux, 1929,67,239 ; A., 1148.23 A. J. Lindsey, AnaEyst, 1930, 55, 503; A., 1263; J. W. Barnes andC. W. Murray, Id. Eng. Chem. (Anal.), 1930, 2, 29; A., 562; F. Martin andJ. Pien, Bull. SOC. chim., 1930, [iv], 47, 646; A,, 1144.p4 L. Szebell6dy, 8. anal. Chem., 1930, 81, 36; A., 1150216 ELLIS AND FOX:and a colorimetric method for tin, utilising stannic sulphide.25Arsenic, antimony, and tin may be separated by successive distil-lations under appropriate conditions ; 26 in the separation of lead andantimony sulphides by digestion with sodium sulphides, sufficientpolysulphide must be present to convert the antimony into thio-antimonate.27It has been found that aluminium hydroxide, precipitated fromalkaline solutions by carbon dioxide, is easily washed and filtered ; 28the hydroxide should be ignited a t about 1300" to yield a non-hygroscopic oxide.29 Blum's method can be applied to alumino-borosilicates without the necessity of previous removal of boron.30Aluminium is quantitatively precipitated by hydrazine arbo on ate,^^whereby separation from iron 32 and manganese 3~ may be effected ;this precipitant has also been used for beryllium.33 Precipitation bymeans of " fusible white precipitate " has been extended to a numberof separ~ttions.~~ In the determination of aluminium by means ofaurintricarboxylic acid, maximum colour intensity is attained a tpH 4.35 Some volumetric methods for iron are given; 36 iron andmanganese may be separated from aluminium and phosphate bymeans of sodium hydroxide and hydrogen per0xide.~7 Ortho-phosphates do not interfere with the colour formation of ferric thio-cyanate as much as pyroph~sphates.~~ A rapid iodometric deter-mination of chromium in the presence of organic substances has beende~ised.~9 Titanium is quantitatively precipitated from feebly acidor ammoniacal tartrate solutions by 8-hydroxyquinoline ; 40 details25 R.Hamsen, Chem.-Ztg., 1930, 54, 143; A., 445.26 H.Biltz, 2. anal. Chem., 1930, 81, 82; A., 1144.27 Idem, ibid., p. 81 ; A., 1147.28 R. Fricke and K. Meyring, 2. anorg. Chem., 1930,188, 127; A , , 727.2s W. Miehr, P. Koch, and J. Kratzert, 2. angew. Chem., 1930, 43, 250;so 0. V. Krasnovski, 2. anal. Chem., 1929,79,175; A., 183.s1 A. Jilek and J. Lukas, J . Czech. Chem. Comm., 1930, 2, 63; A., 444.Idem, ibid., p. 161; A., 727.3ta Idem, ibid., p. 113 ; A., 564.3s A. Jilek and J. Kob, ibid., p. 571 ; A., 1393.s4 B. golaja, 2. anal. Chem., 1930, 80, 334; A., 1012; B. Solaja, M. Kranj-Eevib, and M. Kockar, Arhiv Hemiju, 1930, 4, 136; A , , 1149.35 0. B. Winter, W. E. Thurn, and 0. D. Bird, J . Amer. Chem. SOC., 1929,51,2721 ; A., 1929, 1413.36 F.L. Hahn and H. Clos, 2. anal. Chem., 1929,79,26; A., 54; L. Szebel-16dy,ibid., 1930,81,26; A., 1149; idem,ibid.,p. 97; A., 1149.37 I. S. Teletov and N. N. Andronikova, Ukrain. Chem. J . , 1929, 4, 341;A., 313; 2. anal. Chem., 1930,80,351; A., 1012.38 G, W. Leeper, Analyst, 1930, 55, 370; A., 1012.so F. Feigl, I(. Klanfer, and L. Weidenfeld, 2. anal. Chem., 1930, 80, 5 ;40 R. Berg and M. Teitelbaum, ibid., 81, 1; A., 1160.A., 564; W. Biltz, ibid., p. 370; A., 1148.A., 665ANALYTICAL CHEMISTRY. 217are given for the separation of titanium from other metals 41 and fora colorimetric method of determining this element with gallic acid.42The precipitation of manganese by von Knorre's persulphatemethod has been examined from the gravimetric 43 and volumetric 44standpoint, as also the iduence of cobalt on the bismuthate methodfor manganese.45 Two iodometric methods for zinc are described.46Colorimetric methods of determining cobalt are given ; 47 theinsoluble hydrazine-thiocyanate compounds may be employed forthe determination of cobalt, nickel, and cadmium.48 Phenylthio-hydantoic acid has been further investigated as a precipitant forcobalt,49 and two volumetric methods for cobalt are described.50Small amounts of calcium may be determined after separation astriple nitrite with potassium nickelonitrite 5l or as tungstate. 52Various aspects of the oxalate method for calcium have beenconsidered and it is shown that the oxalate may be converted quantit-atively into the carbonate a t 450" to 500".This observationprovides a great simplification in the determination of calcium. 53Barium chloride can be titratect in neutral or acid solution with alkalisulphate with sodium rhodizonate as indicator.The conversion of magnesium ammonium phosphate into pyro-phosphate is stated to occur below 480°, thus allowing the use of41 L. Moser, K. Neumayer, and K. Winter, Monatsh., 1930, 55, 85; A.,42 P. N. Das-Gupta, J . Indian Chern. SOC., 1929,6, 855; A., 566.p3 J. Majdel, 2. anal. Chem., 1930, 81, 14; A., 1149.44 I . M. Kolthoff and E. B. Sandell, Ind. Eng. Chem. (Anal.), 1929, 1, 181 ;4 5 T. Somiya, J . SOC. Chem. Ind. Japan, 1930,33,255~; A., 1265.46 H. A. Page1 and 0. C. Ames, J . Amer. Chem. SOC., 1930, 52, 3093; A,,1264; R.Lang, 2. anal. Chern., 1929,79,161; A., 182.4 7 A. Lieberson, J . Amer. Chem. SOC., 1930,52,464; A., 445; E. S . Tomula,Suomen Kern., 1929,2, 72; A., 565; A. Blanchetibre and J. M. Pirlot, Compt.rend. SOC. Biol., 1929, 101, 858; A., 1393; M. Delaville, ibid., p. 1082; A.,1393 ; W. Heinz, 2. anal. Chem., 1929,78,427 ; A., 1929,1414.4a P. B. Sarkar and B. K. Datta-Ray, J . Indian Chern. SOC., 1930, 7, 251;A., 882.4s V. Cuvelier, Natuurwetensch. l'ijds., 1929, 11, 131 ; A., 1929, 1414.727.A., 1929, 1414.S. Glasstone and J. C. Speakman, Analyst, 1930, 55, 93; A., 445; A. A.Vaasiliev, 2. anal. Chem., 1929, 78, 439; A., 1929, 1414.s1 A. Astruc and M. Mousseron, Compt. rend., 1930,190, 1558; A., 1011.62 A. Astruc, M. Mousseron, and (Mlle.) N.Bouiasou, ibid., p. 376 ; A., 443 ;M. Mousseron and (Mlle.) N. BOU~SSOU, B d l . 80c. Chim. biol., 1930, 12, 482;A., 1011.63 H. H. Willard and A. W. Boldyreff, J . Amer. Chem. SOC., 1930,52, 1888;A., 881 ; J . T. Dobbins and W. M. Mebane, ibid., p. 1469 ; A., 726 ; M. Stiller,Chern.-Ztg., 1930, 54, 422; A., 1147; Z. Herrmann, 2. anorg. Chem., 1929,184, 289 ; A., 62.64 R. Strebinger and L. von Zombory, 2. anal. Ohem., 1929, 79, 1; A., 53218 ELLIS AND FOX:sintered-glass crucibles.55 On the other hand, the results of acomprehensive inquiry into the methods of obtaining Mg,P,Odemonstrate that a certain concentration of ammonium salts mustbe observed. It is further shown that for accurate work ignition toconstant weight a t 1100" is desirable.Even at 1000" constant weightresults slowly, especially with large precipitates, while a t 1200" thereis a definite loss of weight and low results are obtained. The observ-ation is made that it is more difficult to obtain constant weight indeterminations of magnesium than in determinations of phosphorus. 56The alkali precipitation method for determining magnesium has beeninvestigated. 57The triple acetate method for sodium 58 and the cobaltinitritemethod for potassium 59 continue to attract attention. Othermethods for the latter metal utilise the per-rhenate,60 and triple leadcobaltinitrites. 61The precipitation of indium and its separation from various othermetals are described.62 Precipitation with camphoric acid affords aseparation of gallium from numerous other metals ; 63 three methodsare given for the separation of gallium and alumini~rn.~~ Uraniummay be determined colorimetrically with gallic acid,65 or gravi-metrically following treatment with tannic acid 66 or with 8-hydroxy-quinoline ; 67 the latter reagent also precipitates thorium from aceticacid solution.Ignition of lanthanum oxalate at 450" results in the65 S. S. Miholib, J., 1930, 200; A., 443.6 6 J. J. Hoffman andG. E. F. Lundell, U.S. Bur. Stand. J . Res., 1930, 5,279.67 T. Maeda and R. SyBzi, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1930,13, 185; A., 881.5B H. H. Barber and I. M. Kolthoff, J . Amer. Chem. Soc., 1929, 51, 3233;A., 52; E. R. Caley, Ind. Eng. Chem. (Anal.), 1929, 1, 191; A., 1929, 1412;idem, J .Amer. Chem. SOC., 1930, 52, 1349; A., 726; E. Kahane, J . Pharm,Chim., 1930, [viii], 11, 425; A., 880; idem, Bull. SOC. chim., 1930, [iv], 47,382; A., 726.6s L. Bonneau, ibid., 1929, [iv], 45, 798; A., 49; A. Vassiliev and N.Matveev, 2. anal. Chem., 1930, 81, 106; A., 1146.6O H. Tollert, Naturwiss., 1930,18, 849 ; A., 1392.P. S. Sergeenko, Ukrain. Chem. J., 1930, 5(Sci.), 113; A., 1146; V. I.Tovarnitzki and P. S. Sergeenko, Zhur. Sakharnoi Prom., 1928, 2, 228; A , ,52.L. Moser and F. Siegmann, Monatsh., 1930, 55, 14; A., 564.63 S. Ato, Sci. Papers I w t . Phys. Chem. Res. Tokyo, 1930, 12, 225; A.,64 Idem, ibid., 14,35; A., 1264.65 R. N. Daa-Gupta, J . Indian Chem. SOC., 1929,6, 763; A., 183.B6 Idem, ibid., p. 777; A., 183.67 F.Hecht and W. Reich-Rohrwig, Monatsh., 1929, 53 and 54, 596; A.,564.1929, 1415ANALYTICAL CHEMISTRY. 219formation of a basic carbonate.68 Further studies are recorded ofthe determination of zirconium and beryllium as phosphate^,^^ andof the analytical chemistry of tantalum, niobium, and their mineralassociates.70 Precipitation with tannin and antipyrine permits theseparation of tungsten from various metals,71 with arsenic acid fromvanadium,72 and with benzidine from ar~enates.~3 A rapid reaction,catalysed by phosphates, occurs between vanadyl sulphate andpotassium iodate in hot alkaline solution.7*Osmium and ruthenium may be separated through the differingsolubility in aqueous alcohol of their complexes with strychnine. 75Ruthenium may be quantitatively precipitated by sodium bicarbon-ate.76 Minute quantities of gold may be separated from much iron,lead, and copper by deposition on silk; 77 volumetric methods aregiven for small amounts of silver.78Polonium may be separated from radium-E and -D, and radium-Efrom radium-D, by deposition on silver and nickel respectively,even when present in unweighable amounts.79Further work has been carried out on rubidium chlorostannate ; 8oanhydrous dioxan 81 or acetone serves to extract lithium chloridefrom certain other chlorides. Small quantities of lithium may bedetermined nephelometrically as stearate 83 or centrifugally asphosphate.84A study has been made of the separation of thallium from ter-and quadri-valent metals.85Volumetric methods for determining thiocyanate by means of68 H.J. Backer and K. H. Klaassena, 2. anal. Chem., 1930, 81, 104; A.,69 0. Ruff and E. Stephan, 2. amrg. Chem., 1929,185, 217; A., 184.70 W. R. Schoeller and H. W. Webb, Analyst, 1929, 54, 704; A., 184.71 L. Moser and W. Blaustein, Monatsh., 1929, 52, 351 ; A , , 312.72 A. Jilek and J. Lukas, Chem. Listy, 1930, 24, 73; A., 565.73 Idem, ibid., p. 320; A., 1265.74 J. B. Rarnsey and A. Robinson, J . Amer. Chem. SOC., 1930, 52, 480; A.,7 5 S. C. Ogburn, jun., and L. F. Miller, ibid., p. 42; A., 313.76 R. Gilchrist, Bur. Stand. J . Res., 1929, 3, 993; A., 446.7 7 J. Donau, Milcrochem., 1930, 8, 267; A., 1160.7 8 J. Golse, Bull. SOC. chim., 1930, [iv], 47, 760; A,, 1264; W. Holwech,79 0.Erbacher and K. Philipp, 2. physikal. Chem., 1930,150,214; A., 1394.eo E. Burkser, W. L. Milgevskaja, and R. W. Feldmann, 2. anal. Chem.,81 A. Sinke, ibid., p. 430; A., 1146.*a M. H. Brown and J. H. Reedy, I d . Eng. Chem. (Anal.), 1930, $3, 304;83 E. R. Caley, J . Amer. Chem. SOC., 1930,52,2764; A., 1146.84 B. Brauner, J . Czech. Chrn. Comm., 1930,2,442; A,, 1146.86 L. Moser and W. Reif, Mo&h., 1929,52,343; A., 312.1148.445.Tidsskr. Kjemi Berg., 1930, 10, 78; A., 1392.1930,80,264; A., 881.A,, 1146220 ELLIS AND FOX:permanganate,ss hypobr~mite,~~ and iodine or iodate 88 have beeninvestigated, whilst oxidation for gravimetric purposes may beeffected by hydrogen peroxide in hot alkaline sol~tion.~g Neutral5% potassium chlorate solution, whilst hardly affecting hydrogensulphide, oxidises sulphur dioxide quantitatively when air con-taining these gases is passed through it.90 Conditions for thereduction of sulphate to sulphide by means of calcium hydride arepre~cribed,~~ and a similar reduction by hydriodic acid is followed bycolorimetric comparison by Caro’s reaction for small quantities ; 92reduction by zinc dust is applied to the determination of sulphate inthe presence of aluminium The precipitation of bariumsulphate under varying conditions has been studied, and the resultingprecipitates have been examined microscopically.9* Persulphate isrecommended as a standard oxidising agent in iodometric determin-ations.95The influence of phosphates and of iron on the determination ofsilica by Di6nert and Wandenbulcke’s colorimetric method has beenstudied,ge as also the alkalimetric titration of fluosilicic and fluoboricacids .97A number of volumetric methods for determining cyanides arediscussed; 98 ferric chloride is applied as external indicator in thetitration of ferrocyanide with zinc.99 Perchloric acid is recommendedfor liberating carbon dioxide from carbonates, a special apparatusbeing described.lSeveral papers have appeared dealing with the determination of86 J.Golse, Bull. Soc. Pharm. Bordeaux, 1929, 67, 226; A., 1144; B.Reinitzer and H. Pollet, 2. anal. Chem., 1930,81,286; A., 1391 ; K. Schroder,ibid., p. 308 ; A., 1392.81 J. Golse, Bull. SOC. Pharm. Bordeaux, 1929, 67, 221; A., 1144.88 H.A. Page1 and 0. C. Ames, J . Amer. Chem. SOC., 1930, 52, 2698; A.,8s F. Schuster, 2. anorg. Chem., 1930,186, 253; A., 442.$0 V. G. Gurevitsch, J . Russ. Phys. Chem. SOC., 1930, 62, 111; A., 879.91 W. F. Caldwell with F. C. Krauskopf, J . Amer. Chem. SOC., 1929, 51,$2 I. S. Lorant, 2. physiol. Chem., 1929,185, 245; A., 181.93 H. Ginsberg, 2. angew. Chern., 1930,43,21; A., 441.*C S. Popov and ‘E. W. Neuman, Id. Eng. Chem. (Anal.), 1930, 2, 46; A.,S5 C. V. King and E. Jette, J . Amer. Chem. SOC., 1930, 52, 608; A., 441.96 L. A. Thayer, Id. Eng. Chem. ( A n d ) , 1930,2, 276; A., 1145.*7 E. F. Kern and T. R. Jones, Amer. Electrochem. SOC., May, 1930; A.,0. Reer, Tidsskr. Kjemi Berg., 1929, 9, 127 ; A., 52 ; M. Lora y Tomayo,1144.2936; A., 1929,1411.561.880.Anal.Pis. Quim., 1930, 28, 724; A,, 1392.99 P. F. Felkers, Chem. Weekblad, 1930,27, 209; A., 882.1 C. A. Jacobson and J. W. Haught, Ind. Eng. Chem. (Anal.), 1930,2,334;A., 1146ANALYTICAL CHEMISTRY. 221fluorideY2 of perchlorate,3 the halogenides,* and the phosphorus acidsgenerally. 5Reduction to ammonia is applied to the determination of nitratesand nitrites,6 and of nitrogen itself in gaseous mixtures.' Ferricchloride may be used as indicator in the titration of soluble azideswith sodium nitrite.8Organic Analysis .Qualitative.-M. Wagenaar 9 describes microchemical reactions of(a) strychnine, ( b ) brucine, ( c ) hydrastine, (d) berberine, (e) acoilitine,(f) cytisine, (9) cocaine, and (h) veratrine ; similar tests are describedfor codeine and dionine,lO antifebrin and phenacetin,ll antipyrine,12homatropine and novatropine,l3 thiophen,l* strychnine,15 ephe-E. CarriAre and Janssens, Compt.rend., 1930, 190, 1127; A., 879; E.Carrihre and Rouanet, ibid., 1929, 189, 1281 ; A., 180; J . Casares, Anal. Pis.Qudm. (tech.), 1929,27,290; A., 180; J. G. Fairchild, J. Washington Acad. Sci.,1930, 20, 141 ; A., 726.K. Heller, K. Willingshofer, and B. Sadrawetz, Z. anal. Chem., 1929, 79,256; A., 310; H. H. Willard and J. J. Thompson, I d . Eng. Chem. (Anal.),1930,2,272; A., 1143.R. Lang and J. Messinger, Ber., 1930, 63, [B], 1429; A., 1010; R. G.Turner, J . Amer. Chem. SOC., 1930,52,2768 ; A., 1143 ; S. V. Gorbatschev andI. A. Kasatkina, Z. anorg. Chem., 1930, 191, 104; A., 1143; K.Kuchler,Chem.-Ztg., 1930, 54, 682; A., 1143; H. Szancer, Arch. Pharm., 1930, 268,263 ; A., 726 ; G. G. Longinescu and T. I. Pirtea, Bull. Acad. Sci. Roumuine,1929, 12, No. 7-10, 57; A., 661; R. H. Iclein, Analyst, 1930, 55, 192; A.,561 ; R. Hofmann, Pharm. Zentr., 1930,71,18; A,, 310; H. Ditz and R. May,Z . anal. Chem., 1930,79, 333; A., 310; idem, ibid., p. 371; B., 417.H. EgnBr, Svensk Rem. Tidskr., 1929,4l, 240; A., 1929,1412; T. Kuttnerand L. Lichtenstein, J. Biol. Chem., 1930,88,671; A., 725; K. Hinsberg andD. Laszlo, Biochem. Z., 1930,217,346; A,, 562; L. Brestak and 0. A. Dafert,2. angew. Chem., 1930, 43, 216; A,, 662; A. Dunaiev, Z. anal. Chem., 1930,80,252; A., 880; R. Zinzadze, Z. Pjlanz. Dung., 1930,16, [A], 129; A., 726;A. P.Dunaev, Min. SU~T. Tzvet. Met., 1929, 424; A,, 1010.K. Woidich, Oe~terr. Chem.-Ztg., 1929, 32, 183; A., 1929, 1411.S. N. Blumstein, Z. anal. Chem., 1930,79,324 ; A., 3 11.* J. F. Reith and J. H. A. Bouwman, Pharm. Weekblad, 1930,67,475; A.,880.Pharm. Weekblad, 1929, 66, ( a ) p. 1073; (b) p. 1170; 1930, 67, (c) p. 57,( d ) p. 77, (e) p. 165, (f) p. 205, (9) p. 229, ( h ) p. 393 ; A,, 98, 229, 353, 353, 486,629, 623, 796, respectively.lo G. de Haas, ibid., p. 608; A., 937.l1 L. Ekkert, Pharm. Zentr., 1930, 71, 179; A., 629.l2 Idem, ibid., p. 180; A,, 617.l3 Idem, {bid., p. 641 ; A., 1461.l4 Idem, ibid., p. 625; A., 1460.l6 J . C. Ward and J. C. Munch, J . Amer. Pharm. Assoc., 1930, 19, 954; A.,1456222 ELLIS AND FOX:drine,l6 barbituric acid derivatives,l' glycine,18 cysteine,lg pyridine,20isopropyl alcohol ,21 acetone and formaldehyde ,22 a-napht h01,~~Michler's ketone,24 mono-alkyl- and -aryl-arsinic acids,25 adrenalineF6and various compounds of pharmaceutical interest .27 Rufianic acidprecipitates many organic bases,Z8 but the compounds with thealkaloids are all very similar in appearance ; 29 other precipitantsfor alkaloids are described.30For purposes of identification, derivatives are described ofvarious alcohols with 4'-iododiphenyl-4-crrbimide 31 and with3 : 5-dinitrobenzoyl chloride,32 of organic acids with p-phenyl-phenacyl bromide,33 of aldehydes and ketones with 2 : 4-dinitro-phenylhydra~ine?~ of aldehydes with hippuric of arylaldehydes with indandione,36 of nitriles with magnesium phenylof mercaptans with mercuric bromide, with 3 : 5-dinitro-benzoyl chloride, and with 3-nitrophthalic anhydride,38 and of tertiaryamines with benzyl chloride and with methyl p-toluene s~lphonate.~~l6 J.Sivadjian, J. Pharm. Chim., 1930, [viii], 12, 266; A., 1460.l7 L. van Itallie and A. J. Steenhauer, Pharm. Weekblad, 1930, 67,977 ; A.,1460; G. Deniges, Bull. SOC. Pharm. Bordeaux, 1929,67, 165; A., 788.la W. Zimmermann, 2. physiol. Chem., 1930, 189, 4 ; A., 897.lo R. Fleming, Biochem. J., 1930, 27, 965; A., 1420.'O J. V. Kulikov and T. N. Krestovosdvigenskaja, 2. anal. Chem., 1930, 79,21 H. Leffmann and C. C. Pines, Bull. Wagner Inst. Sci., 1929,4,47 ; A., 318.Idem, ibid., p. 39; A., 1929, 1425; L. Kofler and H.Hilbck, Mikrochem.,462 ; A., 489.1930, 8, 117; A., 940.as 0. Carletti, Biorn. Chim. I d . Appl., 1930,12, 178; A., 908.9' H. Gilman, 0. R. Sweeney, and L. L. Heck, J. Amer. Chem. SOC., 1930,as J. Golse, Bull. SOC. Pharm. Bordeaux, 1929, 67, 84; A., 442.26 H. Bierry and B. Gouzon, Compt. r e d . , 1930,190, 1239; A., 941.17 L. Rosenthaler, Pharm.-Ztg., 1930, 75, 650; A., 941; C. van Zijp,W. Zimmermann, 2. phy&ol. Chem., 1930,188, 180; 189, 155; A., 941,2o L. Rosenthaler, Pharm. Zentr., 1930,71,561; B., 1090.52, 1064; A., 778.Pharm. Weekblad, 1930,67, 189; A., 629.1170.Idem, Amer. J . Phurm., 1929, 101, 724; A., 98; G. D. Lander, Analyst,31 S. Kawai and K. Tamura, Sci. Papers Inst. Phys. Chem. Res. Tokyo,32 G. B. Malone and E.E. Reid, J. Amer. Chem. SOC., 1929,51, 3424; A., 58.33 N. L. Drake and J. Bronitsky, ibicE., 1930, 52, 3715; A., 1436.34 C. F. H. Allen, ibid., p. 2955; A., 1175.56 W. M. Rodionov and A. J. Korolev, 2. angew. Chem., 1929,42,1091; A.,36 M. V . Ionescu, Bull. SOC. chim., 1930, [iv], 47, 210; A., 606.37 R. L. Shriner and T. A. Turner, J. Amer. Chem. SOC., 1930, 52, 1267;a* C. S. Marvel, E. W. Scott, and K. L. Amstutz, ibid., p. 3638; A., 199.1930, 55, 474; A., 1304.1930,13, 260, 270; A., 1159.194.A., 777. 88 E. Wertheim, ibid., 1929, 51, 3661 ; A., 192ANALYTICAL CHEMISTRY. 223The formation of aniline formate serves to identify formic acid:*whilst several tests for acetic acid are given.41 Acids, includinglactones and anhydrides, may be distinguished from phenols bydistillation with zinc dust in a current of hydrogen,& and neutraltartrates and citrates from t’he acid salts by means of ammoniummetavanadate .43Colour reactions of the sugars have been investigated,a as havealso derivatives suitable for identification of 6-ketorhamnonic acid.45Nascent iodine gives colorations with certain aromatic a m i n e ~ .~ ~&uantitatiue.-Further examination has been made of possiblesources of error in organic elementary analysis.4’ Investigations onthe elementary analysis of organic compounds may be reviewedunder the following heads : carbon and hydrogenf8 nitrogen+9halogens generally,50 and iodine in particular, especially whenpresent in small amount,51 sulphur,52 arsenic,53 and mercury.5p Im-40 M. Masriera, Anal. Fie. Quim., 1930, 28, 916 ; A., 1405.41 D. Kriiger and E. Tschirch, Chem.-Ztg., 1930, 54, 42; A., 357; Mibo-chem., 1929, 7, 318; A., 192; Ber., 1929, 62, [B], 2776; A., 62; K. Serke,Apoth.-Ztg., 1929, 44, 1018; A., 489.42 A. W. van der Haar, Rec. trau. chim., 1929,48, 1170; A., 62.48 L. Rossi, Quim. e Id., 1929, 8, 113; A., 357.44 H. Szancer, Pharm. Zentr., 1929, 70, 645, 663, 665; A., 1929, 1426;46 E. VotoEek and S. Malachta, Anal. Pis. Quim., 1929, 27, 494; A., 66.46 W. Ruziczka, Z . anal. Chem., 1930, 80, 185; A., 903.47 J. Lindner and F. Hernler, Ber., 1930, 83, [B], 949, 1123, 1396, 1672;A., 726, 940, 1031, 1198.4a A. Boivin, Bull. SOC. Chim. biol., 1929,11, 1269 ; A., 442 ; K. Lindenfeld,Rocz.Chem., 1930,10, 84; A., 489; E. V. Zappi and A. Manini, Anal. Asoc.Quim. Argentina, 1929, 17, 234; A., 940; M. Nicloux, Compt. rend. SOC. Biol.,1929,102,693 ; A., 1392 ; S . Avery and D. Hayman, Ind. Eng. Chem. (Anal.),1930, 2, 336; A., 1198; J. Meyer and Tischbierek, Z . anal. Chem., 1930, 80,341 ; A , , 940.G. Dorfmiiller, 2. Ver. deut. Zucker-Id., 1930, 80, 407; A., 1166;F. C . Koch, J. Biol. Chem., 1929,84, 601 ; A., 101 ; B. Flaschentrliger, Mibo-chem., 1930, 8, 1; A., 489; E. Zunz, Ann. SOC. Zymol., 1929,1, 236; A., 489.6o J. J. Thompson, J. Amer. Chem. SOC., 1930, 52, 3466; A., 1303; P. W.Robertson, ibid., p. 3023; A . , 1303; G. Illari, Ann. Chim. Appl., 1929, 19,443; A., 101 ; L. Palfray and (Mlle.) D. Sontag, Bull. SOC. chim., 1930, [iv],47, 118; A., 357; S.Sabetay and J. BlBger, ibid., p. 114; A., 318; g. V.Alekseevski and Y. S. Pikazin, J. Appl. Chem. Russia, 1930,3,273; A., 1460.See also p. 207.51 K. Wiilfert, Mikrochem., 1930, 8, 100; A., 441; J. F. Reith, Pharrn.Weekblad, 1929, 66, 829; A., 1929, 1410.62 H. Zahnd and H. T. Clarke, J. Amer. Chem. SOC., 1930, 52, 3276; A.,1303; E. Wertheim, ibid., pp. 1075, 1086; A., 799; H. Emerson, ibid., p.1291 ; A., 799.6s T. von Fellenberg, Mitt. Lebensm. Hyg., 1929, 20, 321; A., 1198; Bio-chem. Z . , 1930, 218, 283; A., 799.64 J. J. Rutgers, Compt. r e d . , 1930, 190, 746; A., 629.S. Tashiro and E. B. Tietz, J. Biol. Chem., 1930,87,307; A., 1198224 ELLIS AND FOX:provements and modifications have been made in the hydrogenationprocess of determining nitrogen,55 sulphur,5G and oxygen.57A critical account and bibliography of methods for the identific-ation and determination of methyl alcohol in presence of ethyl alcoholare given,58 as also are methods for the determination of smallquantities of saturated alcohols.59Some iodometric methods have been examined 6o and also someanalytical reactions of lead tetraethyl.61 Quantitative methods forthe following acids are described : tartaric,62 citric in the presenceof some other organic acids,G3 oxalic in stomach contents,64 andaliphatic mer~apto-acids.~~Nicotine may be precipitated and weighed in the form of its tetra-chloroiodide ; 66 antipyrine and pyramidone, but not the products ofboiling the latter with hydrogen peroxide, give sparingly solublepicrates.67 Quantitative methods, mostly colorimetric, are de-scribed for chlorophyll,68 cholesterol,69 carotinoids, 70 cerebrosides, 71choline,72 arginine,73 cystime,ya proteins,75 trypaflavin and rivanol, 7656 H.ter Meulen, Rec. trav. chim., 1930, 49, 396; A., 629.56 H. ter Meulen, H. F. Opwyrda, and H. J. Ravenswaay, Chem. Weekblad,1930, 27, 19 ; A., 357.6 7 H. ter Meulen, H. J. Ravenswaay, and J. R. G. de Veer, ibid., p. 18 ; A.,367.A. Ionesco-Matiu and C. Popesco, J . Pharm. Chim., 1930, [viKJ, 12, 63;A., 1303.69 W. Ponndorf, 2. anal. Chem., 1930, 80, 401; A . , 1159; P. M. Marrianand G. F. Marrian, Biochem. J., 1930, 24, 746; A . , 1159.6o W. H. Hatcher and W. H. Mueller, Trans. Roy. SOC. Canada, 1920, [iii],23,111, 35; A., 324; R.Signer, Helv. Chim. Acta, 1930,13, 43; A . , 323.61 G. Edgar and G. Calingaert, Ind. Eng. Chem. (Anal), 1929, 1, 221; A.,1929, 1474; K. Dosios and J. Pierri, Z . anal. Chem., 1930, 81, 214; A., 1277.62 H. Besson, J . Pharm. Chim., 1929, [viii], 10,536 ; A., 193 ; P. H. Richert,I d . Eng. Chem. (Anal.), 1930,2,273 ; A., 1163; K. Tiiufel and B. W. Rlarloth,2. anal. Chem., 1930,80, 161; A . , 743.A. I. Kogan, ibid., p. 112; A., 743.64 G. D. Elsdon and J. R. Stubbs, Analyst, 1930,55,321; A., 941.6 6 E. Larsson, 2. anal. Chem., 1929, 79, 170; A., 234.66 F. D. Chattaway and G. D. Parkes, J., 1929, 2817; A., 227.67 S . Erikson, Svensk Farm. Tidskr., 1930,34, 1 ; A., 1199.68 H. B. Sprague and L. B. Troxler, Science, 1930,71,666; A., 1199.70 H.von Euler, H. Hellstrom, and M. Rydbom, Mikrochem., 1929, Pregl71 P. Kimmelstiel, ibid., p. 165; A., 1929, 1474.72 W. Roman, Biochem. Z., 1930,219,218; A., 762.73 C. J. Weber, J . Biol. Chem., 1930,86, 217; A., 755.74 C . Rimington, Biochem. J., 1930, 24, 1114; A., 1420.75 R. Whternitz and Z. Stary, Mikrochem., 1930, 8, 252; A., 1199.76 M. J. Schulte, Pharm. Weekblad, 1930, 67, 809; A., 1304.R. Okey, J . Biol. Chem., 1930, 88, 367; A., 1303.Fest., 69 ; A., 1929, 1474ANALYTICAL CHEMISTRY. 225rhamnose,?' and starch.78 A method for the determination ofmonosaccharrides in presence of lactose involves the use of bufferedBarfoed solution ; 79 under specified conditions, aldose sugars use orremove two equivalents of iodine and three of alkali.80 The effect ofdextrose and sucrose on the determination of lswulose by Nijn'smethod is recorded.81 The process of Baudouin and Lewin for themicro-determination of dextrose has been improved by the additionof barium sulphate, which greatly facilitates dissolution of the mer-cury.82 The micro-determination of various xanthyl derivatives bycomplete oxidation with sulphuric and iodic acids has been workedout .83 Primary arsinic acids may be determined volumetricallywith thymolphthalein as indicator in the presence of sodiumchloride ; 84 volumetric processes are described for diphenylchloro-arsine and diphenylarsine oxide, alone or in admixture.85Guaiacol carbonate is quantitatively brominated in methyl-alcoholic solution ; 86 quinol and pyrocatechol are quantitativelyoxidised by ferric chloride to yuinones, which may be determinediodometrically, the method being applicable in the presence ofphenol, resorcinol, and certain other phenols.87Physical Methods.Slight turbidity in the solution affects the measurements of opticalactivity ; 88 a special polarimeter is described whereby minute con-centrations of laevulose and of dextrose can be accurately deter-mined.89 An optical method for measuring the mercury content ofair has been devised, based on the extent of absorption of themercury line 2537 Sublimation points of numerous substances77 R.A. McCance, Biochem. J., 1929,23, 1172; A., 325.78 L. Paloheimo, Biochem. Z., 1930,222, 150; A., 1167.0.Svanberg, 2. physiol. Chem., 1930,189, 219; A., 894.C. S. Sbter and S. F. Acree, Ind. Eng. Chem. (Anal.), 1930, 2, 274; A.,F. W. Zerban and L. Sattler, ibid., p. 307 ; A., 1165.P. Fleury and J. Marque, J . Pharm. Chim., 1929, [viii], 10,292 ; A., 1929,1106.1426.83 L. Cuny and J. Robert, ibid., 1930, [viii], 11, 241; A., 629.84 H. King and G. V. Rutterford, J., 1930, 2138; A., 1461.86 E; D. G. Frahm and H. L. Boogert, Rec. trav. chim., 1930, 49, 623; A.,86 L. H. Chernoff, J . Amer. Chem. SOC., 1929,51,3072; A., 1929, 1441.87 F. Bock and G. Lock, Monabh., 1929,53 and 54,888 ; A., 1929, 1474.88 H. K. Miller and J. C. Andrews, I d . Eng. Chem. (And.), 1930, 2, 283;941.A., 1142.J. W . Meijer, Rev. Sci. Iwtr., 1930, 2, 69; A., 681.REP.-VOL.XXVTI. H90 K. MiiUer and P. Pringsheim, Natwwiss., 1930,18, 364; A., 727226 ELLIS AND FOX:are recorded at atmospheric pressure and in a vacuum, together withtypical photomicrograph^.^^ Immersion of transparent solids inliquids of approximately the same refractive index causes them toappear various shades of blue when observed through the micro-sc0pe.~2 The technique and application of rotation dispersion to thesolution of chemical problems are reviewed.93 The magnitude of thephoto-electric current generated in the filament of a neon lamp canbe used to indicate the end-point of titrations involving colourchanges or precipitation^.^^Colorimetric methods of analysis are discussed under the headingsof true colorimetry, nephelometry, and titrimetric methods ; 95 someother papers dealing with nephelometry are recorded.96Much work has been carried out on spectrographic methods ofanalysis ; 97 Lowe’s interferometer is applied to the determination ofalkalis in minerals.98Electrolytic.-Thallium is deposited on the anode from a solutioncontaining hydrofluoric acid as an adherent film approximating toT1203,HF.99 The use of Wood’s metal as cathode has been extendedto include the determination of tin, silver, iron, nickel, cobalt, andthallium.1 Two schemes are recorded to avoid the use of platinumelectrodes in the electro-analysis of copper.2 Other work in thissection deals with nickel, cobalt and zinc,3 sodium, potassium, and91 H.Hoffmann, jun., and W. C. Johnson, J . Assoc.08. Agric. Chem., 1930,13, 367 ; A., 1263.92 H. Wagner, 2. angew. Chem., 1930, 43, 686; A., 1263.94 T. Somiya and S. Shiraishi, J . SOC. Chem. Ind. Japan, 1930, 33, 3 0 0 ~ ;e5 N. Schoorl, Chem. Weelcblad, 1930, 27, 52 ; A , , 309.96 J . Erdos, 2. anal. Chem., 1930,80, 122; A., 724; L. T. Fairhall and J. R.Richardson, J . Amer. Chem. SOC., 1930, 52, 938; A., 563; J. A. de Loureiro,Hiochem. Z . , 1930, 224, 337; A., 1391; F. Rimattei, J . Pharm. Chim., 1929,[viii], 10, 349; A., 1929, 1410.97 H. Lundeghrdh, Arkiv Kemi, Min., Geol., 1929, 10, [A], No. 1 ; A., 311;Svensk Kem. Tidskr., 1930, 42,51; A., 560; B. A. Lomakin, 2. anorg. Chem.,1930, 187, 75; A., 445; B. de la Roche, Bull. SOC. chim., 1930, [iv], 47, 660;A . , 1145; P. Urbain, Compt.rend., 1930,190,940; A., 728; J. Papish, L. E.Hoag, and W. E. Snee, I d . Eng. Chem. (Anal.), 1930, 2, 263; A., 1143;J. Papish and D. A. Holt, 2. anorg. Chem., 1930,192,90 ; A., 1393 ; H. Lucas,Physikal. Z., 1930, 31, 803; A., 1264; S. Pifiia de Rubies and J. Dorronsoro,Anal. Fis. Quim., 1929, 27, 778; A., 183; G. Piccardi, Atti R. Accad. Lincei,1929, [vi], 10, 258; A., 313; A. Corsi, Nuovo Cim., 1929,6,275; A , , 441.O 8 G. Burger, Monatsh., 1929, 53 and 54, 985; A., 1929, 1411.99 A. Jilek and J. Lukas, Chem. Listv, 1930, 24, 223, 245; A., 1147.G. Kortiim, ibid., p. 341 ; A., 728.A., 1263.H. Paweck and W. Stricks, 2. anal. Chem., 1929, 79, 115; A., 184.P. S . Tutundiid, 2. anorg. Chem., 1930,190,59; A., 882; J. Guzm&n andA. Rancafio, Anal.Pis. Quim. (tech.), 1939, 27, 269; A., 183.B. Tougarinov, Bull. SOC. c h h . Be&., 1930, 39, 331; A , , 1394ANALYTICAL CHEMISTRY. 227~alcium,~ lead and bi~muth,~ and various metals by ‘‘ internalelectrolysis.” 6Potentimetric.-Attention is drawn to some important points inthe determination of hydrogen-ion concentration. The reactionshave been followed between sodium hydroxide and copper sulphate,*ferrous or ferric ~hloride,~ anti aluminium and magnesium chlorides,present together ; lo and in the last instance also that with sodiumfluoride. Some applications of the titration of mercurous nitratewith alkali oxalates are described ; 11 several papers deal with acid-alkali titrations.12 Methods have been described for the potentio-metric determination of selenium, tellurium, and gold,13 of gold andplatinum,14 nickel,15 zinc,l6 arsenic, antimony, tin, and thallium,f7and copper.18In a series of argentometrio studies, the determination of iodidesand bromides in chlorides,l9 and of halides in presence of sulphites,20has been described. Conditions are prescribed for the titration ofA. Belhk and Z. von Alfoldy, Biochem. Z., 1929,214, 110; A., 52.E. M. Collin, Analyst, 1929, 54, 654; A., 53.H. J. S. Sand, ibid., 1930,55,309; A., 880.I. M. Kolthoff and T. Kameda, J . Amer. Chem. SOC., 1929, 51, 2888;A., 1929, 1410 ; L. Fletcher and J. B. Westwood, J . SOC. Chem. I d . , 1930,49,R. Tomii, E. Okabe, and S. Takeda, Bull. Dept. Appl. Chem. Waseda201T; A , , 1009.Univ. Japan, 1929, 9, 6 ; A., 564. ’ L. W. Elder, jun., Amer. Electrochem. SOC., 1930, May; A., 565.lo W. D. Treadwell with E. Bernasconi, Helv. Chim. Acta, 1930, 13, 500;A , , 1149.l1 C. Mayr and G. Burger, Monatsh., 1929, 53 and 54,493; A., 1929, 1413;ibid., 1930, 56, 113; A., 1264.l2 A. Rius y Mir6, Anal. Pis. Quim., 1929, 27, 605; A., 50; I. I. Shukovand V. M. Gortikov, Z . Elektrochem., 1929,35,863; J . Rws. Phys. Chem. SOC.,1929,61,2056 ; A., 50 ; M. L. Holt and L. Kahlenberg, Amer. Electrochem. SOC.,1930, May; A., 724; F. L. Hahn and R. Klockmann, 2. physikal. Chem.,1930,146, 373; A., 560; B. L. Clarke and L. A. Wooten, J . Physical Chem.,1929, 33, 1468; A., 1929, 1410; F. L. Hahn, 2. angew. Chem., 1930, 43, 712;A., 1263; S. Linda and J. Ettinger, Rocz. Chem., 1929, 9, 504; A., 1929,1411.K. Someya, Sci. Rep Tdhoku Imp. Univ., 1930, 19, 123; A., 725; Z .anorg. Chem., 1930, 187, 337.l4 E. Miiller and W. Stein, Z . Elektrochem., 1930,36,220, 376 ; A., 728, 1013 ;E. Zintl, ibk?., p. 551; A., 1265.l5 T. Heczko, 2. anal. Chem., 1929,78, 325; A., 1929, 1415.l6 S. Sait6, Bull. Inst. Phys. Chsm. Res. Tokyo, 1929, 8, 921; A., 53; N.l7 C. del Fresno and L. Valdbs, AnaE. Pis. Quim., 1929, 27, 595; A., 51.l8 (Miss) M. E. Pring and J. F. Spencer, Analyst, 1930, 55, 375; A., 1011,19 0. Tod6ek and A. Jhnskp, Coll. Czech. Chem. Comm., 1929, 1, 585; A.,51; ibid., 1930, 2, 1, A., 310.go Idem, ibid., 582 ; A., 60.Joassart and E. Leclerc, Bull. SOC. chim. Belg., 1930, 39, 231 ; A., 1011228 RLLTS AND FOX ANALYTICAL CHEMISTRY.phosphates, arsenates, and arsenites with silver nitrate,2f and ofalkali sulphides with sodium nitroprusside.22Conductmetric .-T he t itration between sulphate and bariumacetate and between ferrocyanide and zinc chloride may be followedin boiling, neutral solution by replacing the usual telephone by czsystem whereby the current is measured by a gal~anometer.~~ Themost important applications of conductometric titrations have beensummarised .24B. A. ELLIS.J. J. FOX.21 M. H. Bedford, (Miss) F. R. Lamb, and W. E. Spicer, J. Amer. Chern. 80%22 G. Scagliarini and P. Pratesi, Atti R. Accad. Lincei, 1930, [vi], 11, 193 ;28 G. Jander, 2. angew. Chrn., 1929,42,1037; A., 51 ; G. Jander, A. Pfundt,24 I. M. Kolthoff, Ind. Eng. Chm. (Anal.), 1930, 2, 225; A., 1142.1930,52, 683; A., 442.A., 726.and H. Schorstein, ibid., 1930,43,607; A., 1142