ANALYTICAL CHEMISTRY.ONE of the most interesting analytical publications of the year isthe “ Festschrift ” to Wilhelm Bottger contributed by his pupilsand co-workers. This contains an important paper by I. M. Kolthoffembodying a fundamental discussion of the sensitiveness of pre-cipitation reactions,2 which sets out from the rule laid down byBottger many years ago, namely, E = L + S, where E is thesensitiveness, L is the solubility on the Nernst solubility law, and Sis the visibility of the precipitate. This rule held strictly for silverhalides, but failed in other cases, since the expression involved theassumption that L and 8 were constant. Such an assumption couldscarcely hold strictly except in the few cases of Precipitates wherethe solubility and visibility are largely independent of the particlesize and method of precipitation. Now the variation of solubilitywith particle size for a completely dissociated salt of low solubilitymay be derived by means of the expression RT/M .log S,/8 =2o/pr, in which 8,/S is the ratio of the solubility of particles of smallradius r (of the order of<p) to that of the solubility of fair-sizedcrystals, p is the density, and G the surface tension, other lettersbearing their usual meaning. If the value of SJS is calculated forvarious insoluble substances, e.g., barium sulphate or silver chloride,it is found that increases of solubility of altogether different ordersof magnitude are found, quite apart from questions of the crystallineor colloidal character of the precipitates.This consideration goes along way towards explaining the differences found in the quantitativeprecipitation of substances of the same order of solubility. It alsopoints to the necessity for careful specification of the size of theprecipitated particles when “ supersaturation ” is considered inrelation to quantitative precipitation, for the solubility of bariumsulphate, for example, may be nearly 1000 times as great for smallas for large crystals of the order of 2p, whereas that of silver chlorideremains almost constant within a much wider range of particle size.It follows, further, that if the first precipitate of barium sulphatefrom a very dilute sulphate solution is very small, the solution is notsaturated with reference to barium sulphate.On this account, aswell as that of size of Precipitated particle, and departure fromRayleigh’s law of scattering of light, the visibility term S of Bottger’sexpression cannot be regarded its constant even for the same sub-2. anal. Chem., 1931, 86, 1-190. Ibid., p. 34180 FOX AND ELLIS:stance. Now the intensity of light scattered by particles of smalldimensions varies as nv2/A4, where n is the number of scatteringparticles, v the volume of the particles assumed to be of equal size,and A is the wave-length of the scattered light. Where the particlesare less than 0.1 i . ~ the law is valid. If it is applied to a fixed quantityof precipitate, the peculiar result emerges that the brightness of thescattered light may be much less although the number of scatteringparticles is increased enormously.For example, if the particles are0.01 p a t the start, and grow to 0.1 on standing, the intensity of thelight scattered in the first case is far less than that of the second caseof the larger particles, despite the fact that originally there were1000 times as many scattering particles. This considerationemphasises once again the necessity for the strictest regulation of theconditions of precipitation in nephelometric measurements in orderto obtain particles of constant size with which to conduct determin-ations. It also indicates the need for the observer to obtain calibra-tion curves for each substance he is estimating. When nephelo-metric determinations of sols are made, this is still more necesary,since the intensity of the scattered light does not then follow thelaw in all cases.3The desirability of careful reconsideration of each case wherenephelometric methods are to be employed in atomic-weightdeterminations and similarly accurate work is discussed by C.R.Johnson in a series of papers.* It is commonly assumed that theequal opalescence end-point as used by Richards and Wells for thesodium chloride-silver titration is equally applicable in all cases.Now, the nephelometric method is remarkably sensitive, quite smallchanges in the character of the sols causing relatively large variationsin intensity of the scattered light. Hence the assumption that theopalescence end-point will be equally balanced for multivalent asfor univalent ions does not necessarilyapply.In fact, if the vastlydifferent coagulating powers of multivalent and univalent ions aretaken into consideration, it seems more probable that the former ionswill favour unbalanced actions, thus rendering the equal-opalescenceend-point method doubtful until it has been shown definitely toapply to any particular multivalent ion. Johnson therefore sug-gests an alternative end-point, called " standard solution end-point,"the object being to determine the absolute quantities of silver andhalide ions in the liquid under the conditions of the test, rather thanthe relative quantities as is usually the case. It is shown thatshaking and cooling of the supernatant liquid in determining the3 H.Bechold and F. Hebler, Kolloid-Z., 1922, 31, 70.J . Physical Chem., 1931, 35, 540, 830, 2237, 2581; A., 456, 584, 1141,1256ANALYTICAL CHEMISTRY. 181quantity of chloride may result in leaving an excess of halide in thesupernatant liquor, and such a result would have the effect of lower-ing the value for the calculated atomic weight.The magneto-optic method of analysis has been applied to theinvestigation of the isotopes of Au, Pt, Rh, Ru, Ta, and Th,5 butthe search for element 87 by the method indicated that there is apossibility of obtaining values for the time-lags between Faradayeffect and magnetic field, which are the same for different complexions of very nearly equal molecular weights. Thus, complex ionssuch as SnC1,' or ReC1' will have a molecular weight of about thesame magnitude as would be expected for the atomic weight ofelement 87 and would thus appear in the same position wheninvestigated by magneto-op t ic analysis.For some time past, investigations of spectral absorption of highprecision have been carried out in the infra-red region of the spec-trum, mostly by means of apparatus depending upon the effect ofthe infra-red radiation transmitted by gases or liquids, on thermo-piles of great delicacy, combined with galvanometers of highsensitivity.The technique is not easy, but the circumstance thatcertain groups of atoms gave characteristic bands in the infra-redpointed to the possibility of utilising the measurement of these bandsas a means of analysis.It is, for example, now well established thatcompounds with a C-H group always show oscillation bands veryclose to 0.9 p, 1 p, and 3.4 p, a fact which is easily seen when thebands of chloroform and carbon tetrachloride are compared. Theintroduction of '' neocyanine " sensitised photographic platespermits of the photography of the near infra-red up to about 1 p andbeyond with some ease and rapidity, and it therefore becomespossible to utilise glass spectrographs in this region. In this way,it has been found possible to detect 1% of ethyl or butyl alcohol incarbon tetrashloride, for these substances show the characteristicbands of C-H, but also show the -OH oscillation band a t 0-96 p.This band does not disappear until the concentration of the alcoholis lower than 0.1%.6 It is an interesting point, theoretically, toobserve that the 0.96 p band has its maximum at about 20% con-centration of the alcohol and it becomes weaker on dilution.Thispeculiarity is similar to that observed in the Raman effect withnitric acid, which was attributed to electrolytic dissociation, and asimilar explanation is advanced to explain the diminution inintensity of the -OH bands of the alcohol when dissolved in carbontetrachloride.Owing to the comparative ease with which the Raman spectraF. Allison and E. J. Murphy, Physical Rev., 1930, [ii], 36, 1097.R. Freymann, Compt. rend., 1931, 193, 928182 FOX AND ELLIS:may be obtained, it is not surprising that the attempt to bring themethod into use as an analytical procedure is receiving attention.Itis found that a- and p-pinene, carene, and camphene show charac-teristic displacements of the scattered radiation, and that a terpenemixture gives the Raman spectra of all the constituents. Sincethese spectra are readily picked out, the possibility arises of utilisingthe effect quantitatively.7 A further application is in the detectionof isomerides. For instance, ha-hexene in methylethylcycEopropanegives its characteristic Raman line, 1642 cm.-l, so that some 2% ofthe hexene is detectable.8The use of arc and spark spectra in the quantitative determinationof metals in alloys has made important advances in convenience ofapplication and certainty of results. Particularly striking are theresults now obtained by utilising for the photometer the rotatinglogarithmic wedge-sector as applied originally to spectrum analysisby Scheibe and Neuhausser. The rotating sector in this case is ofentirely different character from that usually employed in determin-ing extinction coefficients in absorption spectra.It consists of adisc from which a part of the periphery is cut away in such a mannerthat the circumferential aperture, 0 (expressed as a fraction of onecomplete revolution), measured a t a, distance 1, radially inwards fromthe outermost part of the disc, follows the relation - log 0 =0.3 + 0.2 1. The advantage of this scheme is that small variationsin the arc or sparking voltages, or in the development of the photo-graphic plates, do not throw the results out.This was one of thedefects of the earlier methods employed by Hartley, Pollock, deGramont, and others. From the shape of the sector opening in frontof the spectrograph slit, it follows that the spectrum lines are thinwedges instead of the ordinary parallel-sided lines. The length ofthe wedges varies with the intensity of the lines, this being the effectof cutting the sector to accord with the logarithmic expression givenabove. In order, then, to apply the method in practice to a metal,say nickel in steel, a number of spectra of standard specimens ofnickel steel is photographed, and the difference in the length of thewedge given by some well-known nickel line from that of a neighbour-ing iron line is plotted against the percentage of nickel.It will beseen that, by employing this difference method of " line-pairs," smallvariations in conditions are eliminated since it is known experi-mentally that the differences remain constant. In a typical case,G. Dupont, P. Daure, and J. Allard, Bull. SOC. chim., 1931, [iv], 49, 1401.* R. Lespieau, M. Bourguel, and R. L. Wakernan, Compt. r e d . , 1931, 193,9 F. Twyman and C. S. Hitchen, Proc. Roy. SOC., 1931, [ A ] , 133, 72; A . ,238; A., 1147.1260ANALYT1CA.L CHEMISTRY. 183for example, the arc lines Nil3415 and FeA3418 are employed,permitting reasonably accurate and rapid determinations of nickelin steel to be made up to 5% of the element.10 A further advantageof the wedge-sector method is that it has been successfully employedfor determining metals in their solutions as chlorides.In this case,a special kind of sparking vessel for the solutions was devised,ensuring constant supply of fresh liquid during the time required forphotographing the spectrum, and eliminating rnculties arisingfrom decomposition of the solutions around the electrodes and fromincrustations. For solutions, an ‘‘ internal standard ” is obtainedby adding a known and definite amount of the chloride of somemetal which does not occur as an impurity in the material underexamination, but which gives lines close to those of the metal beingdetermined. It is often possible to choose pairs of lines, one fromthe standard and one from the metal, whose relative intensities arenot affected by varying spark conditions, so-called ‘‘ homologouspairs ” of 1ines.ll The extent t o which spectrum analysis has nowbeen carried is well illustrated by its utilisation for the analysis ofminerals.12 While it is too much to expect that a complete analysisof a mineral can be made in this way, it is undoubtedly the fact thatmany of the metallic elements and some of the non-metals can bedetermined very accurately by spectroscopic methods.Thesensitiveness of the method may be very great indeed. It has beenshown that as little as 1 y of chromium can be detected with a carbonarc, and as small a quantity as 6 x y when dissolved in fuseda1~mina.l~ Again, as little as 0.5 part per million of aluminium canbe estimated approximately in the ashes from biological material,14using pure copper electrodes for production of the arcs.A com-prehensive investigation on the determination of certain elementssuch as titanium in aluminium by utilisation of “ homologous pairsof lines ” is now available, with details of the manner in which thisprocedure may be utilised practically.15Attention is directed to a development in the methods of determin-ing halogens, including fluoride, in organic compounds. There arefew convenient and rapid methods for this purpose, especially incompounds containing high proportions of halogens. The processemploying sodium and absolute alcohol fails in many cases, givinglow results, and the method of oxidation by hot sulphuric acid andlo F. Twyman and A. A. Fitch, J .Iron Steel Inst., 1930, ii, 289.l1 E. Schweitzer, 2. anorg. Chem., 1927, 164, 127.l2 See F. Lgwe, Fortschr. Min., 1927, 12, 220.J. Papish and W. J. O’Leary, I d . Eng. Chem. (AnaE.), 1931, 3, 11 ; A.,455.l4 D. Tourtelotte and 0. S. Rask, ibid., p. 97; A., 662.l5 A. Schleicher and J. Clermont, 2. anal. Chern., 1931, 86, 191, 271184 FOX AND ELLIS:an oxidising agent also has limitations and requires special apparatusfor successful operation. E. Chablay l6 first utilised the action ofsodium dissolved in liquid ammonia for determining halogens inorganic compounds, and this was followed by F. B. Dains and his co-workers l7 and by C. w. Clifford.18 The process has been re-examinedand simplified so that it is available as an ordinary laboratorymethod.I n some cases, where two halogen atoms are attached to thesame carbon atom, cyanide is formed, but this is eliminated in theprocess described by T. H. Vaughn and J. A. Nie~w1and.l~ Toavoid the delay in decomposition resulting from insolubility of theorganic compound in liquid ammonia, an organic liquid unacted onby sodium in ammonia is added, e.g., dimethylacetal or ether. Thereaction is then complete in a few minutes, and ammonium nitrateis added to the liquid ammonia before this is allowed to evaporateand the excess of sodium destroyed. The halogen is determined inthe sodium halide by the usual methods, and the process is statedto be suitable for micro-determinations. An important advantageof this method is that it can be used to decompose organic fluorinecompounds containing other halogens as well.Some definite advances are announced in the practical develop-ment of the use of thermionic valves as accessories for determiningpH values and in potentiometric titrations of all kinds.Especiallyimportant is the use of non-aqueous solvents as applied to thedetermination of the acidity of organic substances such as oils. Oneof the earlier suggestions was to use amyl or (later) butyl alcoholsaturated with lithium chloride and containing quinhydrone.20At first, the alcoholic solution of lithium chloride was used both as areference half-cell and for dissolving the oil, but later a silver-silverchloride half-cell was found to answer. Since a saturated solutionof lithium chloride in butyl alcohol is not a good solvent for oils orresins, a more convenient method was devised by B.L. Clarke,L. A. Wooten, and K. G. Compton.21 I n this case the problem isto overcome the difficulty arising from butyl-alcoholic solutions ofhigh specific resistance. The principle adopted for measuring thetitration is to arrange the circuit so that any change in the potentialof the indicator electrode causes a large deflexion of some indicatingmeter, and this is secured by using vacuum tubes which have highgrid insulation. The procedure is to dissolve the oil in dry butylalcohol containing a little quinhydrone, and add about one-tenth ofAnn. Chim., 1914, [ix], 1, 510.Ibid., 1919, 41, 1051.l7 J . Amer. Chem. SOC., 1918, 40, 936; 1920, 42, 1573.19 I d .Eng. Chem. (Anal.), 1931, 3, 274; A., 1393.2O H. Seltz and L. Silverman, ibid., 1930, 2, 1 ; B., 1930, 248.z1 Ibid., 1931, 3, 321ANALY!CICAL CHEMISTRY. 185the volume of saturated lithium chloride-butyl alcohol mixture.The liquid is kept free from air in a flask filled with nitrogen, and theindicator electrode is bright platinum wire immersed in the liquid,the reference electrode being a calomel half-cell with an agar-agarsalt bridge. A curve is plotted for the titration, giving micro-ammeter deflexions against volume of reagent used. Very sharpmaxima of the curves are readily obtained at the end-point.The problem of potentiometric titrations in cases where readilyreducible substances are present and the hydrogen electrode is inapplic-able is one that arises from time to time in practice. Tungsten elec-trodes seemed to, present possibilities and were found to be usefulin certain solutions;22 they would appear to offer scope for moreextended application.A useful electrode is the antimony-antimon-ous oxide electrode, for it has been shown to be available for suchdifficult titrations as hydrocyanic, sulphurous, selenious, and telluricacids with a, very fair degree of accuracy.23Despite its convenience, the glass electrode has not received theextended use it deserves in determinations of pH values, although i tcan be used for measurements up to p= 9.5 or thereabouts. Part ofthis is doubtless due to the very high resistance of the glass bulbsused, but this need not be serious if the special glass now availableis used, for the resistance may be reduced to a few megohms, therebypermitting the convenient utilisation of the valve electrometer.Animportant scheme is given in detail by C. Morton 24 for the determin-ation of glass-electrode potentials by a ballistic method which getsrid of a troublesome feature, namely, the " creeping " of the zero ofthe galvanometers. This has been accomplished by the introductioninto the anode circuit of a high resistance, across which is thegalvanometer in series with a large capacity of 4 pF or so. We havefound this scheme quite satisfactory in use, especially where obser-vations have to be continued over long periods.There is not much information available on p , values at com-paratively high temperatures, despite the necessity for having suchdata when determinations have to be made in conditions wherecooling is inadvisable. The scheme laid down by S.Stone 25 istherefore of importance. It describes suitable forms of electrodevessels and electrodes. The silver-silver chloride reference electrodeis used in conjunction with a platinum-hydrogen electrode, and p Rvalues for buffer mixtures up to 10 and above 100" are recorded.The change in pH may be positive or negative and is nearly constantin most mixtures for a considerable range of p H .22 H. T. S . Britton and E. N. Dodd, J., 1931, 829; A., 699.23 H. T. S . Britton and R. A. Robinson, ibid., p. 458; A., 585.24 Ibid., p. 2977. 25 Rec. trau. chim., 1930, 49, 1133; A., 184186 FOX AND ELLIS:There is little doubt that, wherever possible, actual determinationof the pH by a potentiometric method is on the whole more satis-factory than colorimetric methods, which are, however, goodenough for much practical work when it is sufficient to know thep , within about & 0.1 unit.Numerous factors influence theaccuracy of the colorimetric tests, &ch as salt effects, proteineffects, and particular errors due to the indicators themselves.Wide-range indicators have to be used with care and may lead toerroneous results in unbuffered solutions such as extracts obtainedin paper testing, from soils, sugar liquors, and so on. Theseindicators are safe with well-buffered liquids or in those cases wherethe p H of the indicator is near that of the liquid under test.It isusually better to use a number of short-range indicators wheneverthe solution is suspected to be unbuffered.26 A further considerationin the preparation of the indicators is that considerable variationsin colour may occur in several ways, especially from the method ofpreparing the indicator, its storage, andIt must always be remembered in the use of coloured indicatorsfor determining pH, that salts may have a definite effect on thecolour of an indicator, and that this varies with the concentrationof the latter. This effect has been measured and even applied todetermine the dissociation of acetic acid.28 The salt error may withsome indicators be serious enough in certain alkaline buffers them-selves, e.g., glycine buffers, to show large discrepancies betweenthe p , values of sodium hydroxide solutions and those of thestandard buffer which gives the same colour with the indicator.29These considerations emphasise the necessity for considering care-fully the choice of indicator in relation to the liquid under examin-ation.For turbid liquids there are the so-called “achromaticindicators,” which are mixtures of indicators so chosen that themiddle point of the colour change in one is complementary to thatof the other, the resulting transition point of the mixed indicatorbeing grey.3o As an example, a mixture of bromocresol-green,neutral-red, and phenolphthalein indicates sharply at pE 4-5 and 8.5,and is therefore available for the titration of phosphoric acid.An interesting method of identifying a solid when the meltingpoint cannot be used because of decomposition, depends upondetermining the b.p. of the saturated solution in a suitable apparatus.If the solid under test is the same as the solute, then the b. p. of the26 F. R. McCrumb, I n d . Eng. Chem. (Anal.), 1931, 3, 233; A., 1023.27 M. G. Mellon and G . W. Ferner, J . Physical Chem., 1931, 35, 1025.28 N. V. Sidgwick and L. A. Woodward, Proc. Roy. Xoc., 1930, [ A ] , 130, 1.20 J. W. McBain, (Miss) M. E. Laing, and 0. E. Clark, J. Gen. Physiol.,30 E. L. Smith, Quart. J . Pharm., 1930, 499; A., 184.1929, 12, 695ANALYTICAL CHEMISTRY. 187saturated solution will not be affected on addition of the unknownsubstance.With due precautions the procedure is available likewisefor ascertaining the purity of a s~bstance.~~A problem which is sometimes of considerable importance inanalysis is the determination of the density of solids when smallquantities only are available. Heavy liquids of suitable range arenot always available for the denser materials. A device is describedwhich gives satisfactory results with as little as 0.05 g. of solid,whether in the form of powder or massive.32 This consists of aglass tube fitted with a capillary side arm on which there are twomarks. The quantity of some suitable liquid, weighed from a weightburette, required to occupy the space between the two marks isascertained. A determination can then be made readily, by fillingthe tube as far as the lower mark with the liquid, introducing aweighed portion of the solid, and then introducing sufficient Iiquidto fill the instrument to the second mark from the weight burette.It is obvious that the weight of liquid displaced by the solid can befound with some accuracy provided precautions be taken to reducevaporisation when volatile liquids are used.The discovery that per-rhenates of certain organic bases, e.g.," nitron," give insoluble compounds is of much value for determiningthe element.Rhenium sulphide may be precipitated from a hotsolution of a rhenium salt acidified with hydrochloric acid. Theprecipitation is rather slow, but the insoluble sulphide is easilyconverted into per-rhenate by suspending it in sodium hydroxidesolution and adding hydrogen peroxide.From an acetic acidsolution the rhenium can be obtained quantitatively as nitron~er-rhenate.~~ The sulphide reaction is delicate, and the precipit-ation with nitron is nearly complete, particularly if nitron acetate ispresent.34 A difficulty arises from the co-precipitation by nitronof any molybdenum present in the solution. Fortunately, molyb-denum can be removed as Mo02(C9H60N), by the use of 8-hydroxy-quinoline in acetic acid solution, leaving the rhenium in solution.35The separation of the bulk of the molybdenum may be effected bydistillation of rhenium chloride a t 175-20O0 from a sulphuric acidsolution of the per-rhenate. The precipitation of the remainingmolybdenum by hydroxyquiiioline can then be carried 0 ~ t .~ 5 ~ Analternative method of estimating rhenium takes advantage of the31 J. 0. Halford, J . Amer. Chem. Xoc., 1931, 53, 2640; A., 1022.32 E. W. Blank, Ind. Eng. Chem. (Anal.), 1931, 3, 9 ; A., 456.33 W. Geilmann and F. Weibke, 2. anorg. Chem., 1931,195, 289; A., 328.34 W. Geilmann and A. Voigt, ibid., 1930, 193, 311 ; A., 1930, 1547.55 W. Geilmann and F. Weibke, ibid., 1931, 199, 347; A., 1143.S5a Idem, ibicE., p. 120; A., 1025188 FOX AND ELLIS:insolubility of thallous per-rhenate 35h from a solution acidified withacetic acid. The thallous per-rhenate is weighed after being drieda t 140", but the results are somewhat low, most likely owing tovolatilisation.Inorganic Analysis.Qualitative.-The sensitivity of certain tests is increased byshaking the aqueous solution with an immiscible and byobservation under strong ill~mination.~~ Schemes are proposedfor the systematic detection of the commoner k a t i ~ n s , ~ ~ and certainanions,39 using 0.1-g.samples. A detailed summary has been madeof the application of organic reagents to mineral qualitative analysis ;40the sensitivity of such reagents generally increases with their mole-cular weight.41 Notes are given for the detection of traces ofchromate in presence of permanganate, of hydrogen sulphide inwater,42 and of nickel in cobalt salts,43 and further observations aremade on the detection of certain heavy metals with diphenylthio-~arbazide.~~ Quinoline 45 and hexamethylenetetramine, ammonia,and h y d r a ~ i n e , ~ ~ have been applied as microchemical reagents ;certain metals afford colour reactions with ammonia in presenceof resorcin01,~7 and the properties of hydroxylamine as a precipitanthave been e~amined.~SAmmoniacal picric acid gives characteristic crystalline precipitateswith copper and some other heavy metals; 49 2 : 7-diaminofluorenecan serve as reagent for copper, zinc, and ~adrnium,~O and " direct-35b F.Krauss and H. Steinfeld, 2. anorg. Chem., 1931, 197, 52; A., 589.36 I. Stone, Ind. Eng. Chem. (Anal.), 1931, 3, 325; A . , 1022; see also Feigl37 W. Bottger and B. M. Schall, ibid., Emich Festschr., 1930, 29 ; A., 1930,3 8 A. Scheinkmann, 2. anal. Chem., 1931,83, 176; 85, 344; A., 587, 1260;39 Idem, ibid.; S. I. Dijatschkovski and T. I. Isaenko, J . Gen. Chem. Russia,40 B. Tougarinoff, Ann. SOC. Sci. Bruxelles, 1930, 50, [B], 145; A . , 188.4 1 V. V. Tamchyna, Mikrochem., 1931, 9, 229; A., 701.42 F. Feigl, ibid., Emich Festschr., 1930, 125; A., 1930, 1547.43 Idem, ibid.; F. Feigl and H. J. Kapulitzas, 2. anal. Chem., 1930, 82,44 H. Fischer, Mikrochem., 1930, 8, 319; A., 328.45 I. M. Korenman, Pharm. Zentr., 1930, 71, 769; A., 1931, 188.46 P. Rby and P. B. Sarkar, Mikrochem., Emich Festschr., 1930, 243; A . ,47 L. Bey, Bull. SOC. chim., 1930, [iv], 47, 1192; A., 1930, 1545.48 J. C. Roldhn, Anal. Fds. Quim., 1930, 28, 1080; A . , 1930, 1547.49 I. M. Korenman, Pharm. Zentr., 1931, 72, 225 ; A., 701 : J . Chem. Ind.Russia, 1931, 8, 276; A., 927.50 J.Schmidt and W. Hinderer, Ber., 1931, 64, [B], 1793; A., 1045.and others, Mikrochem., 1931, 9, 165; A., 590.1545.C. J. van Nieuwenberg, Mikrochem., 1931, 9, 199; A., 698.1931, 1, 81 ; A., 925.417; A., 455.1930, 1544ANALYTICAL CHEMISTRY. 189green B ” for c0pper.5~ Boiling potassium cyanide solution dis-solves zinc, but not cadmium cyanide; 52 methods are describedfor the detection of zinc and silver,54 bismuth,55 andcadmium. 56The elements of the aluminium group are separated from thoseof the iron group by boiling the nitric acid solution with sodiumcarbonate, hydroxide, and peroxide; 57 2 : 2‘-dipyridyl in slightlyacid solution is a sensitive test for ferrous salts, with which it givesa red coloration.58 Reactions of simple and complex iron com-pounds have been investigated.59 The detection’ of chromium 6oand of manganese 61 in minerals and rocks is described, as alsoa number of methods for cobalt, as czesium cobaltinitrite,62 withsodium thi~sulphate,~~ with thi~glycollanilide,~~ and with eriochromeblue-black B and red B.65pNitrobenzeneazoresorcino1, besides being a specific reagent formagnesium,66 is a useful indicator over the range p H 10.8-13.0;a number of other dyes has been investigated, but in all cases cobaltand nickel give the same reactions as magne~ium.~’ For themicrochemical detection of sodium, a uranyl acetate solution isused; 68 modifications of the triple acetate test have been made.69Molybdic acid gives a violet coloration with potassium cetyl-51 P.Sisley and David, Bull. Soc. chim., 1930, [iv], 47, 1188; A., 1930,52 N. A. Tananaev and N. S. Fedulov, Ukraine Chew. J., 1930, 5, (Sci.),53 K. M. Filimonovitsch, ibid., p. 383; A., 927; A. Sergeev, ibid., p. 227;54 A. Sergeev, loc. cit.55 G. Lochmann, 2. anal. Chem., 1931, 85, 841; A., 1262.56 J. S. Pierce and W. T. Forsee, I d . Eng. Chem. (Anal.), 1931, 3, 188;b7 S. Ato, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1930, 14, 287;5 8 F. Feigl and H. Hamburg, 2. anal. Chem., 1931, 86, 7 ; A., 1261.59 0. Baudisch, Biochem. Z . , 1931, 232, 35; A., 589.H. Leitmeier and F. Feigl, Tsch. Min. Petr. Mitt., 1931, 41, 95; A., 455.61 H. Leitmeier, ibid., p. 87; A., 454.62 H. Yagoda and H. M. Partridge, J . Amer. Chem. SOC., 1930, 52, 4857;63 M.G. de Celis, Anal. Pis. Quim., 1931, 29, 262; A., 814.64 T. Bersin, 2. anal. Chem., 1931, 85, 428’; A . , 1262.6 5 E. Eegriwe, ibid., 1930, 82, 150; A , , 1930, 1547.66 J. V. Dubskj. and A. Ok”, Chem. Listy, 1930, 24, 492; A., 327; I.B7 I. M. Kolthoff, Milcrochem., Emich Festschr., 1930, 180; A., 1930, 1544.68 A. Martini, ibid., 1931, 9, 422; A., 926.P. Feldstein and A. M. Ward, Analyst, 1931, 56, 245; A., 587; R.Montequi and R. de SBdaba, Anal. Pis. Quim., 1931, 29, 255; A., 812.1546.213; A . , 327.A., 327.A,, 701.A., 454.A., 329.Stone, Science, 1930, 72, 322; A., 56190 FOX AND ELLIS:xanthate; 70 delicate tests €or zirconium 71 and germanium 72 aredescribed, as also observations on Feigl's rhodanine reagent forsilver, which gives colorations with gold and palladium.73Limits are given for the sensitivity of the colour reaction of freehalogens with p-aminodimethylaniline. 74 A drop test for thedetection of bromides depends on the formation of eosin fromfluorescein ; 75 preferential precipitation of silver chloride is utilisedfor detecting chlorides in presence of bromide. 76 Chlorates producean opalescence when shaken with saturated aqueous hydrogensulphide, whereas perchlorates and nitrates do not .77 Additionof a solution of benzidine acetate to one of a fluoride in presenceof mercuric acetate affords, under certain conditions, a yellowprecipitate. 78or inpresence of thiocyanate 80 is described. Capillary tubes are recom-mended for storing reagents such as diphenylamine which areunstable in solution ; the 2 : 4-diamino-6-hydroxypyrimidine re-action may be applied to the microdetection of nitrite.81 Thereaction of nitric acid with diphenylbenzidine follows a coursesimilar to that with diphenylamine, but the colour is about twiceits intense and much more affected by excess of reagent.82 Areaction with an acid-alcoholic solution of vanillin occurs withhydrogen peroxide or perborates.83&uccntitative.-Tartrazine and phenosafranine are shown to besuitable adsorption indicators for the mutual titration of chlorideor bromide with silver nitrate.S* Several papers deal with electro-70 J. V. Tamchyna, Chem. Listy, 1930, 24, 465; A . , 329.7 1 F. Pavelka, Mikrochem., 1930, 8, 345; A., 329 ; F.Feigl, P. Krumholz,72 W. Geilmann and K. Briinger, 2. anorg. Chem., 1931, 196, 312 ; A . , 455.73 F. Feigl and H. Leitmeier, Tsch. Min. Petr. Mitt., 1931, 41, 188; A.,701; F. Feigl, P. Krumholz, and E. Rajmann, Mikrochem., 1931, 9, 165;d., 590.A drop method for detecting ferrocyanide when aloneand E. Rajmann, ibid., 1931, 9, 395; A., 928.74 H. E. Tremain, Ind. Eng. Chem. (Anal.), 1931, 3, 225; A., 699.7 5 A. V. Pavlinova, Ukraine Chem. J., 1930, 5, (Sci.), 231; A . , 325.7 6 G. G. Longinescu and T. I. Pirtea, Bull. Acad. Sci. Roumaine, 1930, 13,7 7 T. P. Raikova-Kovatscheva, 2. anal. Chem., 1930, 82, 415; A . , 451.7 8 C . Pertusi, Atti I I I Cong. Naz. Chim., 1929, 573; A . , 925.'9 A. V. Pavlinova and T. N.'Bach, Ukraine Chem.J., 1930, 5, (Sci.), 235;80 Idem, ibid., p. 233; A., 326.81 F. L. Hahn, Mikrochem., Emich Festschr., 1930, 143; A., 1930,a2 H. Riehm, 2. anal. Chem., 1930, 81, 439; A., 1930, 1542.83 C. Griebel, Mikrochem., 1931, 9, 313; A., 925.84 A. J. Berry and P. T. Durrant, Analyst, 1930, 55, 613; A . , 56.195; A . , 185.A . , 326.1542AXALY!Mc)AL CHEMISTRY. 191metric methods for ascertaining p3H85 and with oxidation-reductionindicators.86 Sixteen dyes of different colours have been selectedas suitable internal indicators in volumetric bromate reactions. 87The manner in which the chlorine ion contaminates a numberof precipitates shows that three types of precipitation process maybe recognised. 88 Despite criticism,sg J. Dick upholds his methodfor the rapid drying of precipitates and extends it to a numberof 0thers.~1 A white rod and much indicator are used €or thetitration of dark-coloured liquids.92 The technique of accuratevolumetric analysis as applied to delicate w0rk,~3 the sources oferror in micro-acidimetric tit ration^,^^ the factors affecting deter-minations with the centrif~ge,~5 and the analytical sigdcance ofageing phenomena 96 are discussed.The benzidine reaction for " active " iron may also be used inalcoholic solution and is most sensitive at p , 3.95.97 The presenceof more than 5% of iron prevents the removal of phosphate byboiling with a nitric acid solution of stannous 11itrate.~8Errors in the determination of water by drying are discussed; 99other methods involve decomposition of a-naphthyloxychloro-85 R.J. Fosbinder, J. Lab. Clin. Ned., 1931, 16, 411; A., 811 ; I. M.Kolthoff and T. Kameda, J. Amer. Chem. SOC., 1931, 53, 821; A . , 585;H. T . S. Britton and R. A. Robinson, J., 1931, 458; A., 585; P. Vignon,J. SOC. Leather Trades' Chm., 1931, 15, 367; A., 1141; V. Morani, Ann.Chim. Appl., 1931, 21, 83; A., 450; S. 0. Rawling and G. B. Harrison,Phot. J., 1931, 71, 108; A., 450; M. Kilpatrick, jun., and E. F. Chase, J.Arner. Chem. Soc., 1931, 53, 1732; A., 811; S. Stone, Rec. trav. chim., 1930,49, 1133; A . , 184; B. Elema, (:hem. Weekblad, 1931, 28, 223, 234; A., 699;H. T . S. Britton and E. N. Dodd, J., 1931, 829; A., 699.88 I. M. Kolthoff and L. A. Sarver, J. Amer. Chem. SOC., 1930, 52, 4179;A., 54; J.Knop, 2. anal. Chem., 1931, 85, 253; A., 1256; L. Michaelis, J.Biol. Chem., 1931, 91, 369; A., 687.G. F. Smith and H. H. Bliss, J. Amer. Chem. SOC., 1931, 53, 2091; A . ,925.88 2. Karaoglanov and B. Sagortschev, 2. anorg. Chem., 1931, 198, 352;A . , 926.68 L. Moser and L. von Zombory, 2. anal. Chem., 1930, 81, 95; A., 1930,1149.O0 Ibid., 1931, 83, 105; A , , 584.91 Idem, ibid., 1930, 82, 401 ; A., 453.E. Rossmann, Chem.-Ztg., 1931, 55, 403; A., 810.O3 W. Ponndorf, 2. anal. Chem., 1931, 84, 289; 85, 1 ; A . , 1022, 1259.O4 J. Mika, Mikrochem., 1931, 9, 143; A., 584; 2. anal. Chem., 1931, 86,O 5 K. S. Greene, J. Amer. Chem. SOC., 1931, 53, 3275; A., 1256.O 6 H. Fischer, 2. angew. Chern., 1930, 43, 919; A., 1930, 1541.O 7 A. Simon and T. Reetz, 2.anorg. Chem., 1930, 194, 89; A., 57.s9 M. Dolch and K. Buche, PJlanzenbau, 1930, 4, 6 4 ; A., 1023.54; A., 1256.A. Kriiger, 2. anal. Chem., 1930, 82, 62; A., 67192 FOX AND ELLIS :phosphine,l distillation with chlorinated hydrocarbonsY2 and ebul-lioscopic procedure with methyl alcohol or a ~ e t o n e . ~ Formuhare derived for calculating the state of combination of the con-stituents in mineral waters based on the dissociation constants ofthe acid radicals present and the pH of the water; * methods aregiven for the determination of fluorine, cEsium and rubidium,6and arsenic, molybdenum, and bismuthArsenite solutions are best prepared by dissolving arseniousoxide in carbonate-free sodium bicarbonate solution. Sulphatesof such aromatic amines as aniline and toluidine serve satisfactorilyas standards in alkalimetry ; perchloric acid is similarly applied.loStandardisation of thiosulphate solution by means of ceric sulphateis described.llMicrochemical methods are applied to the determination oftraces of various metals, of hydrogen and carbon monoxide iniron, and of metallic carbonyls in air; l2 the determinations andseparations of the metals of the hydrogen sulphide group have beencritically studied,13 as has also the separation of lead from barium,strontium, and calcium sulphate with ammonium acetate.14 Con-ditions are given for the quantitative separation of lead as chromatefrom iron,l5 bismuth,16 mercury and copper ; l7 precipitation as1 E.Dittler and H.Hueber, 2. anorg. Chem., 1931, 195, 41; A., 325;ibid., 199, 17; A . , 1023; J. Lindner, 2. anal. Chem., 1931, 86, 141; A . , 1257.2 T. R. Fairbrother and R. J. Wood, Ind. Chem., 1930, 6, 442; A . , 185;H. Lundin, Chem.-Ztg., 1931, 55, 762; A., 1256; G. Middleton, Phurm. J.,1931, 12'7, 86; A., 1023.in mineral waters.S. Bakowski, Rocz. Chem., 1931,11, 49, 269, 490; A . , 585, 811, 1023.4 L. Fresenius and 0. Fuchs, 2. anal. Chem., 1930, 82, 226; A . , 1930,5 J. Casares and R. Casares, Anal. Pis. Quim., 1930, 28, 1159; A., 55.6 L. Fresenius, 2. anal. Chem., 1931, 86, 182; A., 1256.8 I. Tananaev, Ukraine Chem. J., 1930, 5, (Sci.), 217; A . , 326.1541.0. Steiner, ibid., 1930, 81, 389; A . , 1930, 1541.E. Strasser, 2. anal. Chem., 1930, 82, 114; A ., 1930, 1541.450 ; see also G. F. Smith and 0. E. Goehler, ibid., p. 61 ; A., 451.1283; A . , 700.1930, 107; A . , 1930, 1546.10 G. F. Smith and W. W. Koch, Ind. Eng. Chem. (Anal.), 1931,3,52; A.,11 N. H. Furman and J. H. Wallace, jun., J. Amer. Chem. SOC., 1931, 53,12 R. Lucas, F. Grassner, and E. Neukirch, Mikrochem., Emich Festschr.,13 P. Wenger and C. Cimerman, Helv. Chim. Acta, 1931, 14, 718; A . , 1261.14 I. Majdel, Arhiv Hemiju, 1930, 4, 76; A . , 1930, 1544; 2. anal. Chem.,1931, 83, 36; A., 453; F. Feigl and L. Weidenfeld, ibid., 84, 220; A . , 926;W. W. Scott and S. M. Alldredge, Ind. Eng. Chem. (Anal.), 1931, 3, 32; A.,453.1 5 H. Funk and 0. von Zur-Muhlen, 2. anal. Chem., 1931,85,435; A., 1260.16 H. Funk and J. Weinzierl, ibid., 1930, 81, 380; A., 1930, 1545.3 7 H.Funk and J. Schormiiller, ibid., 82, 361; A., 187ANALYTICAL CHEMISTRY. 193chromate from dilute perchloric acid is recommended.18 Neutralsolutions of lead salts may be titrated with molybdate l9 or sodiumThe oxychloride is preferred for the separation ofbismuth from lead; 21 lead and bismuth may be titrated by thefiltration method 22 previously used for calcium, magnesium, e t ~ . ~ ~Cadmium may be determined gravimetrically or volumetricallyby means of ammonium m0lybdate.~4 Further observations havebeen made on the use of salicylaldoxime as a reagent for copper ; 25its place may be taken, though without advantage, by variousstructurally-related compounds.26 Separation of copper fromcadmium may be effected with gallic acid 27 or potassium formate,2sand from zinc with iodide and thio~ulphate.~~ Among volumetricmethods for copper, the iodide 3O and one involving permanganateoxidation following precipitation by Spacu’s reaction have receivedattentioa31 Copper and titanium are precipitated from slightlyacid solution by 5 : 7-dibromo-8-hydro~yquinoline.~~The precipitated mercuric sulphide obtained directly from acidsolution is excessive; 33 a method is evolved, particularly fororganic compounds, involving distillation as mercuric chloride ina stream of gaseous hydrogen ch1oride.a Volumetric methods aredescribed for mercuric cyanide 35 and mercurous chloride,36 andD.J. Brown, J. A. Moss, and J. B. Williams, Id. Eng. Chem. (Anal.),1931, 3, 134; A., 701.l@ R.C. Wiley, P. M. Ambrose, and A. D. Bowers, ibid., 1930, 2, 415; A , ,1930, 1545.2o S. Komaretzky, 2 . anal. Chem., 1931, 84, 407; A., 1024; E. Beneschand E. Erdheim, Przemys-t Chern., 1931,15, 153; A . , 701.21 W. Hertel, Metall u. Erz, 1930, 27, 557; A . , 588.22 H. T. Bucherer and F. W. Meier, 2. anal. Chem., 1931,83, 351 ; A . , 588.23 Idem, ibid., 1930,82, 1 ; B., 1930, 1153.24 R. C. Wiley, Ind. Eng. Chem. (Anal.), 1931, 3, 14; A., 453.25 0. L. Brady, J., 1931, 106; F. Ephraim, Ber., 1931, 64, [B], 1215; A.,26 F. Ephraim, Ber., 1931, 64, [:B], 1210; A., 813.27 P. N. Das-Gupta and H. Saha, J . Indian Chem. SOC., 1931,8,19; A . , 813.28 E. I. Fulmer, Ind. Eng. Chem. (Anal.), 1931, 3, 257; A., 1025.2s H. Brintzinger, 2.anal. Chem., 1931, 86, 167; A., 1260.R. Intonti, Ann. Chim. Appl., 1930, 2Q, 583; A., 187; B. Park, Ind.31 J. Golse, Bull. SOC. chim., 1931, [iv], 49, 84; A., 454: L. Cuny, J . Pharm.32 R. Berg and H. Kiistenmacher, Mikrochem., Emich Festschr., 1930, 26 ;33 E. P. Fenimore and E. C . Wagner, J . Amer. Chem. SOC., 1931,53,2453;34 Idem, ibid., p. 2461; A , , 1025.35 E. Cattelain, J . Pharm. Chim., 1930, [viii], 12, 529; A., 187.36 D. Koszegi, Pharm. Ztg., 1931, 76, 524; A., 813.813 : W. Reif, Mikrochem., 1931, 9, 424; A., 927.Eng. Chem. (Anal.), 1931, 3, 77; A . , 454.Chim., 1931, [viii], 13, 513; A., 813.A . , 1930, 1546.A., 1025.REP.-VOL. XXVm. 194 FOX AND ELLIS :Deniges’s cyanide method has been modified.37 The importanceof determining minute traces of mercury is again emphasi~ed.~~Bismuth, aluminium, and zinc, precipitated by S-hydroxy-quinoline are determined colorimetrically with a phosphotungsto-molybdate reagent ; 39 a method has been devised €or determiningsmall quantities of bismuth in organs without decomposing them.40Reduction of stannic salts by lead41 and of antimony also byhypophosphorous acid 42 prior to titration have been examined,particularly as regards the interfering effects of other metals ;reduction with iron powder for small amounts of tin is preferred toaluminium.43 Some notes on the Gutzeit arsenic test are recorded ; 44conditions are given for the use of iodide catalyst in the titrationof arsenious acid and ~ermanganate.~~Diphenylaminesulphonic acid is recommended as indicator forthe titration of iron, especially as tungstate does not interfere,46despite its larger correction.47 Further data are recorded on thepractical applications of Knop’s original method ; 48 p-phenetidinehas also been used as the indicator,49 and on the micro-scale, varioustriphenylmethane dyes.50 The oxidation of ferrous iron by iodinein presence of phosphate proceeds slowly to ~ompletion.~~ Ironmay be separated from manganese by hydrazine hydrate,52 fromcobalt by various mercury-ammonium derivatives, 53 and fromzinc, manganese, etc., by he~amethylenetetramine.~~37 0.Procke, Coll. Czech. Chem. Comm., 1930, 2, 593; A., 1930, 1546.38 A. Stock, Naturwiss., 1931, 19, 499; A., 1025 ; A. Stock, H. LUX, F.Cucuel, and F.Gerstner, 8. angew. Chem., 1931, 44, 200; A., 588; B. L.Moldavski, J . Appl. Chem. Russia, 1930, 3, 955; A., 589.39 M. Teitelbaum, 2. anal. Chem., 1930, 82, 366; A., 188.40 N. A. Valiaschko and P. K. Virup, Ukraine Chem. J., 1930, 5, (Sci.),41 S. G. Clarke, Analyst, 1931, 56, 82; A., 590.42 B. S. Evans, ibid., p. 171 ; A., 590.43 R. Holtje, 2. anorg. Chem., 1931, 198, 287; A., 928.44 T. J. Ward, Analyst, 1930, 55, 630; A., 55; J. P. Mayrand, J . Amer.Pharm. ASSOC., 1931, 20, 637; A., 1024.4 5 R. Lang, 8. anal. Chem., 1931, 85, 176; A., 1258.46 L. A. Xarver and I. M. Kolthoff, J . Amer. Chem. Xoc., 1931, 53, 2902;A., 1141. 4 7 Idem, ibid., p. 2906; A., 1141.4 8 C. J. Xchollenberger, ibid., p. 88; A., 328; 0. Rothe and A.P. Sobrinho,Rev. brasil. Chim., 1929, 1, 129; A., 814.49 L. Szebellddy, Magyar Chem. Pol., 1930, 36, 40; A., 188.6o J. Knop and 0. Kubelkov&, 8. anal. Chem., 1931, 85, 401 ; A., 1261.51 W. D. Bonner and H. Romeyn, jun., I n d . Eng. Chem. (Anal.), 1931, 3,52 A. JilekaridV. Vicovskf, Coll. Czech. Chem. Comm., 1931,3,379 ; A., 1261.53 B. golsja and V. Matovinovid, Arhiw Herniju, 1931, 5, 232; A., 1260.54 1’. Ray, A. K. Chattopadhya, and D. Bhaduri, 2. anal. Chem., 1931,275; A., 702.85; A., 454.86, 13; A., 1281ANaLYTICAL CHEMISTRY. 195If iron and nickel are present, a single treatment with hypobro-mite does not suffice to oxidise chromium salts completely,55 butthey can be so oxidised by perchloric acid.56 Observations aremade on the determination of the oxide content of aluminium,57and on the precipitation of aluminium, chromium, and iron bypotassium cyanate.58 Aluminium may be precipitated by hydrazinecarbonate. 59The precipitation of manganese salts by water-soluble carbon-ates,60 the oxidation by persulphate in presence of silver salts,61and precipitation as manganese ammonium phosphate G2 have beenexamined. Precautions to be observed during precipitation ofcobalt 63 and nickel 64 as sulphide and subsequent conversion intometal and oxide respectively are enumerated, and also in the cobaltthiocyanate colorimetric comparison.65A scheme for the determination of zinc combined in mixtures asoxide, silicate, ferrite, sulphate, and sulphide is presented.66 Smallconcentrations of lead do not interfere with the precipitation ofsmall quantities of zinc by S-hydroxyq~inoline.~~Following precipi tation of oxalate, an alkalimetric titration isapplied to small amounts of calcium.68 Calcium, barium, andstrontium, present in pairs, itre separated by the varying solubilityof their bromides in isobutyl d ~ o h o l .~ ~ For precipitation of calciumas oxalate in presence of arsenate, a slight excess of ammonia a thigh temperature is recommended.70 For micro-determination,5 5 E. Schulek and A. Dbzsa, Z. anal. Chem., 1931,86, 81; A., 1262.5+3 L. H. James, Ind. Eng. Chem. (Anal.), 1931, 3, 258; A . , 1026.5 7 A. M. Shandorov, Tzwet. Met., 1930, 672; A . , 813: H. Lowenstein, 2.5 8 B. J. F. Dorrington and A. M. Ward, Analyst, 1930, 55, 625; A ., 56.59 A. Jilek and J. Lukas, Chem. Listy, 1930, 24, 365; A . , 1930, 1547.6O Idem, ibid., 1931, 25, 225, 249; A., 927; Coll. Czech. Chem. Comm., 1931,3, 1S7; A . , 702.61 R. Lang and F. Kurtz, 2. anal. Chem., 1931, 85, 181; A., 1261; J. H.van der Meulen, Chem. .WeekbZad, 1931, 28, 377; A., 927.62 P. Nuka, Latwij. Uniw. RaEsti, 1931, 2, 1 ; A., 1142.63 M. M. Haring and M. Leatherman, J. Amer. Chem. SOC., 1930,52, 5135;64 M. M. Haring and B. B. Westfall, ibid., p. 5141; A., 325.6 5 E. S. Tomula, 2. anal. Chem., 1931, 83, 6 ; A., 454.66 V. Tafel and G. Sille, 2. angew. Chem., 1930, 43, 948; A . , 1930, 1545;13’ M. E. Stas, Pharm. Weekblud, 1931, 68, 93; A . , 453.6 8 C. H. Fiske and E. T. Adams, J. Amer. Chem. SOC., 1931, 53, 2498;A., 1024; C. H.Fiske and M. A. Logan, J. Biol. Chem., 1931, 93, 211; A.,1342.69 L. SzebellBdy, Magyar Chenz. Pol., 1929, 35, 59, 63, 100; A., 186, 187.70 J. T. Dobbins and W. M. Mebane, J . Amer. Chern. SOC., 1930, 52 4285;anorg. Chem., 1931, 199, 48; A., 1025.A., 325.1931, 44, 792; A., 1260.A., 56196 FOX AND ELLIS:calcium is precipitated as triple nitrite with potassium and nickel,71as ~ x a l a t e , ~ ~ or as picrolonate; 73 a method in which calcium andmagnesium are titrated in the same solution is specially suited forthe analysis of dolomite.74 Calcium may conveniently be separatedfrom magnesium by precipitation as molybdate. 75 Direct volu-metric methods for barium depend upon the use of sodium rhodiz-onate as indicator 76 and upon the fact that potassium chromatereacts alkaline to bromothymol-blue and phenol-red.77 Variousmethods of determination of strontium a,nd of its separation fromcalcium are reviewed.78 Investigations on magnesium may bedivided into those using phosphate 79 and those involving use of8- hydroxyquinoline. 8OVarious modifications and adaptations of the triple acetatemethod for sodium and the cobaltinitrite method for potassium s2have been made. The direct sulphate method gives low resultsin the presence of 5-substituted barbituric acids.83 Other methods71 M. Mousseron, Bull. SOC. Chim. biol., 1930, 12, 1014; A., 1930, 1543;ibid., 1931, 13, 831 ; A., 1259.72 L. Velluz and R. Deschaseaux, ibid., p. 797; A., 1259; Compt.rend.SOC. Biol., 1930, 104, 976 ; A., 588.73 R. Dvorzak and W. Reich-Rohrwig, 2. anal. Chem., 1931, 88, 98; A.,1259.74 K. L. Maliarov, J . Russ. Phys. Chem. SOC., 1930, 62, 1529; A., 56;Mikrochem., 1931, 9, 132; A., 588; compare also G. A. Pantschenko, UkraineChem. J., 1930, 5, (Sci.), 187; A., 327.7 5 R. C. Wiley, Ind. Eng. Chem. (Anal.), 1931, 3, 127; A., 701.' 6 L. Zombory, Magyar Chem. Pol., 1929, 35, 90; A., 187.7 7 S. Balachovski, 2. anal. Chem., 1930, 82, 206; A., 1930, 1544.7 8 W. Noll, 2. anorg. Chem., 1931, 199, 193; A., 1259.'9 J. I. Hoffman and G. E. F. Lundell, Bur. Stand. J . Res., 1930, 5, 279 ;A . , 55; M. Javillier and D. Djelatides, Ann. Palsif., 1931, 24, 133; A., 701;V. NjegovanandV.Marjanovid, Arhiv Hemiju, 1931,5,243; A., 1259; idem, 2.anal.Chem., 1930, 82, 154; A., 1930, 1544; J. Majdel, ibid., p. 425; A.,452.J.C.RedmondandH.A.Bright,Bur.Xtand. J.Res., 1931,6,113; B.,396;F. L. Hahn, 2. anal. Chem., 1931,86, 153; A., 1259; W. A. Hough and J. B.Ficklen, J . Amer. Chem. SOC., 1930,52,4752; A., 327; K. Nehring, 2. Pfla<nz.Dung., 1931, 21, [A], 300; A., 1142; R. Berg, W. Wolker, and E. Skopp,Mikrochem., Emich Festschr., 1930, 18; A., 1930, 1546.A. M. Butler and E. Tuthill, J . Biol. Chem., 1931, 93, 171; A., 1342;J. T. Dobbins and R. M. Byrd, J . Amer. Chem. SOC., 1931, 53, 3288; A.,1259; E. R. Caley and D. V. Sickman, ibid., 1930, 52, 4247; A., 56; A.Blenkinsop, J . Agric. Sci., 1930, 20, 511; A., 186; R. A. McCance and H. L.Shipp, Biochem. J . , 1931, 25, 449; A., 926.82 J.Fischer, Biochem. Z . , 1931, 238, 148; A., 1259; R. A. Herzner,ibid., 237, 129; A., 1259; P. J. Van Rysselberge, I n d . Eng. Chem. (Anal.),1921, 3, 3; A., 452; P. N. Grigoriev and S. S. Korol, J . Chem. I d . , Russia,1931, 8, 68; A., 700.83 G. W. Collins, I d . Eng. Chem. (Anal.), 1931, 3, 291; A,, 1024ANALYlTCAL CHEMISTRY. 197for potassium depend upon titration of the acid tartrate,s4 uponcolorimetric comparison of the picrate,s5 and upon the use of lithiumchloroplatinate. 86 To convert alkali sulphates into chlorides insilicate analysis, they are heated with hydrazine hydrochloride ; 1 3 ~small quantities of alkalis are separated from acids insoluble inwater, e.g., tungstic acid, by electrodialysis.88Beryllium may be separated from aluminium by means of guan-idine carbonate; 89 the sulphite process of separating these twoelements has been reinve~tigated~~o and further details given forthe microanalysis of beryllium silicate rocks.91 For low concen-trations of titanium, accurate results by the colorimetric methodare obtainable by comparing solutions of identical c01our.~~ Furtherseparations of gallium by means of camphoric acid are rec0rded.~3For molybdenum, the permanganometric method 94 and precipit-ation as lead molybdate95 have been examined.In the presenceof molybdate, tungsten is determined colorimetrically by meansof rhodamine-B, otherwise a quinol sulphate solution may be used.96Potassium chloride acts as an anti-oxidant, enabling manipulationof uranous compounds to be carried out within an hour or so in thepresence of air ; 97 zirconium is quantitatively precipitated byexcess of selenious acid from hot slightly acid solutions.98 I n theseries of investigation on the analytical chemistry of tantalum,niobium, and their mineral associates, a detailed technique isdescribed 99 and also the separation of titanium from zirconiumand hafnium.1 Quantitative conversion of lanthanum oxalateinto oxide does not occur below 800";.coprecipitation of basicL. Clarke and J. M. Davidson,.Ind. Eng. Chem. (Anal.), 1931, 3, 324;A . , 1024.8 5 E. R. Caley, J . Amer. Chem. SOC., 1931, 53, 539, A., 452.8 c G. F. Smith and A. C. Shead, ibid., p. 947; A., 587.W. Mylius, Sprechsaal, 1930, 63, 972; A ., 700.8 8 G. Heyne, 2. angew. Chem., 1931, 44, 328; A., 926.89 A. Jilek and J. Kota, Coll. Czech. Chem. Comm., 1931, 3, 336; A., 1024.91 H. Thurnwald and A. A. Benedetti-Pichler, Mikrochem., 1931, 9, 324;ga H. Ginsberg, 2. anorg. Chem., 1931, 198, 162; A . , 814.93 S. Ato, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1931, 15, 289; A,,v4 T. Doring, 2. anal. Chem., 1930, 82, 193; A . , 1930, 1548.95 H. A. Doerner, Metal Id., London, 1930, 37, 444; A . , 589.96 G. Heyne, 2. angew. Chem., 1931, 44, 237; A . , 589.9 7 C . Ouellet, Helv. Chim. Acta, 1931, 14, 967; A . , 1262.O 8 S. G. Simpson and W. C. Schumb, J. Amer. Chem. SOC., 1931, 53, 921;99 W. R. Schoeller, Analyst, 1931, 56, 304; A., 814.A. Travers and Schnoutka, Compt. rend., 1931, 192, 285; A., 452.A ., 927.927.A . , 590.A. R. Powell and W. R. Schoeller, ibid., 1930, 55, 605; A., 57198 FOX AND ELLIS:chloride may be avoided by adding the lanthanum solution to alarge excess of soda or ammonia.2Full details are given of a procedure recommended for the de-termination of ~ s m i u m . ~ Special attention has been given to thedetermination of small quantities of ~ i l v e r . ~ The chemical reactionsof polonium are reviewed, with special reference to their analyticalsignificance.Iodometric and gravimetric methods are described for thedetermination of small amounts of thallium, the former beingapplied particularly to organs.The boric acid-alcohol flame coloration has been applied quantit-atively.8 Boric acid may be separated from dilute sulphuric acidsolutions of heavy metal salts by distillation with methyl alcohol ;this process has been used for natural waters and plant materials.1°Carbon monoxide is oxidised to dioxide by a suspension of iodinepentoxide in oleum,ll by copper oxide deposited on quartz,12 andby silver oxide.13 A number of modified methods of determiningcarbon dioxide are described; l4 the aniline method and the sodiumiodide-acetone method have been adapted to give concordant resultsfor carbonyl chloride in presence of other chlorine compounds.152 I.M. Kolthoff and (Miss) R. Elmquist, J . Amer. Chem. SOC., 1931, 53,3 R. Gilchrist, Bur. Stand. J . Res., 1931, 6, 421; A., 814.4 E. Schulek, Mikrochem., Emich Fest,schr., 1930, 260; A., 1930, 1543;J.Golse, Bull. SOC. Pharm. Bordeaux, 1930, 68, 53; A., 452 : C. Egg, Schweiz.med. Woch., 1929, 59, 84; A,, 186.1225; A., 702.5 M. Guillot, J . Chim. physique, 1931, 28, 14; A., 591.0 R. Fridli, Magyar Gy6. Thrsas. &rt., 1929, 5, 479; A., 56; Deut. 2. yes.7 L. Moser and W. Reif, Mikrochem., Emich Festschr., 1930, 215; A.,8 W. Stahl, Latvij. Univ. Raksti, 1930, 1, 369, 400; A , , 326; 2. anal.8 E. Schulek and G. Vastagh, ibid., 1931, 84, 167; A., 812.gerichtl. Med., 1930, 15, 478; A., 328.1930, 1545.Chem., 1931, 83, 268, 340; A., 587.10 L. V. Wilcox, Ind. Eng. Chem. (Anal.), 1930, 2, 358; A., 1930, 1543.11 H. A. J. Pieters, Chem. Weekblad, 1931,28, 335; A., 812; 2. anal Chem.,1931, 85, 50; A., 1258.12 A. Schmidt, 2.angew. Chem., 1931, 44, 152; A., 926; H. A. J. Pieters,2. anal. Chem., 1931, 85, 113; A., 1258.13 Idem, ibid.; W. Manchot and G. Lehmann, Ber., 1931, 64, [B], 1261;A., 926.l4 C. A. Jacobson and J. W. Haught, Bull. West Va. Univ. Sci. ASSOC.,1930, 2, No. 4, 8; A., 700; E. M. Emmert, J . Assoc. Off. Agric. Chem., 1931,14, 386; A., 1142; U. Boklund, Biochem. Z., 1931, 233, 478; A., 1024;J. Lindner and F. Hernler, Mikrochem., Emich Festschr., 1930, 191; A.,1930, 1543; M. Nicloux, Compt. rend. SOC. Biol., 1929, 101, 182; A., 186.15 J. C. Olsen, G. E. Ferguson, V. J. Sabetta, and L. Scheflan, Ind. Eng.Chem. (Anal.), 1931, 3, 189; A., 700ANALYTICAL CHEMISTRY. 199Hydrogen is readily absorbed by a silver permanganate reagent ; l6two manometric methods for the determination of hydrogen peroxideare described.17 Work on helium is continued.18Continuing his bromo-iodometric investigations, J.H. van derMeulen 19 describes methods (a) of determining iodate and bromatetogether, ( b ) of determining iodate, bromate, and chlorate together,(c) of oxidising bromide to bromate with hypochlorite, ( d ) of destroy-ing excess of hypochlorite by boiling with sodium formate or alittle osmic acid, ( e ) of reducing chlorate to chloride by arsenite,with osmate as catalyst, (f) or by ferrous sulphate in presence ofhydrobromic acid and osmate as catalyst. Other papers in thehalogen group deal with bromides,21 iodine and iodides,22and fluorides.23Some conditions for determining nitrates by phenoldisulphonicacid are laid down.24 Nitrates are quantitatively reduced electro-l6 F.Hein and W. Daniel, Chem. Fabr., 1931, 381; A., 1256.l7 A. Fujita and T. Kodama, Biochem. Z., 1931, 232, 15; A., 699.F. Paneth and W. D. Urry, Mikrochem., Emich Festschr., 1930, 233;A., 1930, 1543; Z. physikal. Chem., 1931, 152, 110, 127; A., 327; ibid.,Bodenstein Festband, 1931, 145; A., 1258; V. A. Sokolov, Neft. Khoz., 1930,19, 292 ; A., 452.l9 Chem. Weekblad, 1930, 27, ( a ) p. 578; ( b ) p. 618; 1931, 28, (c) p. 82;( d ) p. 235; ( e ) p. 258; (f) p. 348; A., 1930, 1542; 1931, 55, 325, 699, 699,811.2o A. V. Frost, Trans. Inst. Pure Chem. Reagents, 1929, No. 300, 187; A.,1930, 1541; G. G. Longinescu and T. J. Pirtea, Bul. Chim. Soc. RomlinciStiin., 1928, 31, 77; A., 585; I.E. Orlov, Z. anal. Chem., 1931, 84, 185;A., 811; A. B. Keys, J., 1931, 2440; A., 1257; V. N. Kolitscheva and R. V.Teis, J . Russ. Phys. Chem. Soc., 1930, 62, 1957; A., 450 : 0. TomiEek and 0.ProEke, Coll. Czech. Chem. Comm., 1931, 3, 116 ; A., 450 ; H. RUOSS, Z. anal.Chem., 1930,81, 385 ; A., 1930, 1541 ; Cousin and DUfour, J . Pharm. Chim.,1930, [viii], 12, 439; A., 55.21 Z. Szabb, Z. anal. Chem., 1931, 84, 24; A., 811; B. S . Evans, Analyst,1931, 56, 590; B., 1009 ; M. Bobtelsky and R. Rosovskaja-Rossienskaja,2. anorg. Chem., 1931, 199, 283; A., 1257.22 R. W. Teiss, Z. anal. Chem., 1930, 82, 116; A., 1930, 1542; H. Ditz,Z. anorg. Chem., 1930, 194, 147; A., 185; F. L. Hahn, ibid., 1931, 195, 75;A., 325; H. A. Liebhafsky, J .Amer. Chem. SOC., 1931, 53, 165; A., 325;R. E. Remington, J. F. McClendon, and H. von Kolnitz, ibid., p. 1245; A.,699; P. Fleury and J. Courtois, BUZZ. SOC. chim., 1931, [iv], 49, 860; A.,1023.23 A. Kurtenacker and W. Jurenka, Z. anal. Chem., 1930, 82, 210; A.,1930, 1542; M. Karasiliski, Bull. Acad. Polonaise, 1931, [A], 143; A., 1257;P. Mougnaud, Compt. rend., 1931, 192, 1733; A., 1023; A. V. Frost, Trans.Inst. Pure Chem. Reagents, 1931, 10, 53; A., 925; G. Batchelder and V. W.Meloche, J . Amer. Chem. Xoc., 1931, 53, 2131 ; A., 925 ; H. Ginsberg, Chem.-Ztg., 1931, 55, 608.24 B. A. Skopintzev, J . Appl. Chem. Russia, 1930, 3, 747; A., 326; Z.anal. Chem., 1931, 85, 244; A., 1257200 FOX AND ELLIS:lytically at a copper or nickel cathode.25 A phosphate buffer ofpH 7.4 is recommended for the recovery of free ammonia fromammonium chloride and sulphate solutions ; 26 oxidation of am-monia to nitrogen by bromine is quantitative in solutions of p=76---9.5.27 A volumetric method for very small quantities ofammonia, especially in waters, is described.28 Alkali azides aretitrated with silver nitrate in presence of potassium chromate ; 29hydrazine and semicarbazide may be determined by oxidationwith potassium iodateY30 and nitrites colorimetrically with rivanol ; 31the reaction between nitrite and iodide has been examined.32Several papers deal with the determination of phosphoric acid ; 33and methods are given for the removal of phosphate ions fromsolution in analysis.34 Hypophosphites and arsenites are deter-mined by reaction with mercuric chloride.35 Potassium perman-ganate is applied colorimetrically as a reagent for lower oxides inphosphoric oxide.36Modifications have been introduced into certain methods ofdetermining persulphate to increase their accuracy ; 37 a schemeis proposed for mixtures of Caro’s acid, persulphate, and hydrogenperoxide.38 Further observations are made on volumetric methodsfor ~ulphates,3~ and on the precipitation as barium sulphate in the26 L.Szebellhdy and B. M. Schall, 2. anal. Chem., 1931, $6, 127 ; A., 1257.26 M. S. Nicholls and M. E. Foote, Ind. Eng. Chem. (Anal.), 1931, 3, 311 ;27 B. Levy, 8. anal. Chem., 1931, 84, 98; M. Tschepelevetzky, S. Posd-A., 1023.niakova, and R. Fein, ibid., p.106; A., 1024.S. K. Hagen, ibid., 83, 164; A., 586.2s A. Majrich, Chem. Obzor, 1930, 5, 3; A., 186.3O V. Hovorkrt, Coll. Czech. Chem. Comm., 1931, 3, 285; A., 925.31 W. M. Rubel, 8. Unters. Lebensm., 1930, 60, 588; A., 586.32 C. A. Abeledo and I. M. Kolthoff, J. Amer. Chem. Soc., 1931, 53, 2893;A., 1142.33 A. del Campo, Anal. Pis. Quim., 1930,28, 1153; A., 55; H. T. Buchererand F. W. Meier, 2. anal. Chem., 1931, 85, 331 ; A., 1258; H. Thurnwald andA. A. Benedetti-Pichler, ibid., 86, 41 ; A., 1258 ; S. L. Lieboff, J . Lab. Clin.Med., 1931,16,495; A., 1258; R. Biazzo, Ann. Chim. Appl., 1931,21,21, 75;A., 452; ibid., p. 105; A., 700; G. DenigBs, Bull. SOC. Pharm. Bordeaux,1930, 68, 1 ; A., 927 ; M. Ishibashi, Chikashige Anniv. Vol., 1930, 1 ; A., 586 ;A.von EndrBdy, 2. anorg. Chem., 1930,194, 239; A., 186.34 A. Kegans, Latvij. Univ. Raksti, 1929,1, 65; A . , 1930, 1543; J. Bougaultand E. Cattelain, J. Pharm. Chim., 1931, [viii], 14, 97; A., 1142.35 A. Ionesco-Matiu and (Mme.) A. Popesco, ibid., 13, 12; A., 326.36 J. W. Smith, J., 1931, 528; A., 587.37 A. Kurtenacker and H. Kubina, 2. anal. Chem., 1931, $3, 14; A . , 452.38 K. Gleu, 2. anorg. Chem., 1931, 195, 61; A., 326.I. M. Kolthoff and E. 13. Sandell, Ind. Eng. Chem. (Anal.), 1931,3,115; A.,451 ; Chatron, J. Pharrn. Chim., 1931, [viii], 13,244; A . , 586; M. Dominikiewicz,Bull. Trav. Dep. Chim. Inst. Hyg. Ztat. (Poland), 1930, 31, No. 1, 3; A., 185ANALYTICAL CHEMISTRY. 201presence of lead salts 40 and of various chromium compound^.^^ Abuffered ammonia solution is added prior to the oxidation ofthiocyanate by iodine.42With the view of application to the analysis of natural selenides,methods have been devised for determination of copper 43 andsilver selenites 44 in the presence of the corresponding selenides.For the rapid precipitation of selenium, large quantities of hydrazinehydrochloride are recommended.45 Both selenious and silicicacids may be determined colorimetrically by reaction with pyrrolealthough the colour fades rather rapidly.46 A nitric-perchloricacid mixture is used for the determination of silica in vegetablesubstance^.^'Organic Analysis.Qualitative.-For purposes of identification of various phenolsthere are described the corresponding phenoxyacetic acids 48 and3 : 5-dinitrobenzoates ; 49 of fatty acids, the p-bromophenacylesters and alkylbenziminazoles; 51 of alcohols, the p-nitro-phenylurethanes ; 52 of alcohols and phenols, the p-xenylcarb-amates; 53 of primary and secondary alcohols and certain phenols,the hydantoin-3-acetates; 54 of carbonyl compounds, the 2 : 4-dinitrophenylhydrazones ; 55 of halides, as 3 : 5-dinitrobenzoates 5640 B.TBzak, Arhiv Henziju, 1930, 4, 7 8 ; A., 1930, 1542.41 E. A. Eikitina and A. V. Ihbajeva, Trans. Inst. Pure. Chem. Reagents,42 H. A. Page1 and H. J. Koch, J. Amer. Chem. SOC., 1931, 53, 1774; A . ,43 W. Geilrnann and F. W. Wrigge, 2. anorg. Clbem., 1931, 197, 353; A.,44 F. W. Wrigge, ibid., p. 369; A., 813.*5 E. Benesch and E. Erdheim, Chem.-Ztg., 1930, 54, 954; A., 185; K.4 6 R.Berg and M. Teitelbaum, Mikrochem., Emich Festschr., 1930, 23;4' L. Lematte, G. Boinot, E. Kahane, and (Mme.) M. Kahane, Compt. rend.,48 C . F. Koelsch, J. Amer. Chem. Xoc., 1931, 53, 304; A . , 345.49 M. Phillips and G. L. Keenan, ibid., p. 1924; A., 837.5O S . G. Powell, ibid., p. 1172; A., 621.51 R. Seka and R. H. Muller, Monatsh., 1931, 57, 97; A . , 600.5 2 R. L. Schriner and R. F. B. Cox, J . Amer. Chem. SOC., 1931, 53, 1601;53 G. T. Morgan and A. E. J. Pettet, J., 1931, 1124; A., 834.6 4 R. Locquin, V. Cerchez, and A. A. Policard, Bull. SOC. chim., 1931, [iv],5 5 0. L. Brstdy, J., 1931, 75tj; A., 937.5 6 C. L. Tseng and E. J. H. Chu, Nat. Centr. Univ. Sci. Rep., [A], 1930,1931,10, 20; A., 925.811.813.Wagenmann and H.Triebel, Metall u. Erz, 1930, 27, 231 ; A., 186.A., 1930, 1546.1931,192, 1459; A., 926.A . , 709.49, 595, 600, 602, 607; A., 966.1, 9 ; A., 504.G 202 FOX AND ELLIS:and as anilides; 57 of ethers, as alkyl 3 : 5-dinitrobenzoates orbromo-derivatives. 58The sensitivity of various methods, old and new, for the detectionof carbon disulphide has been a~certained.5~ The blue colorationproduced with iodine and lanthanous salts is a delicate test foracetic acid; benzoic acid and homologues of acetic acid reactsimilarly or inhibitatively.60 Colour reactions are described forcertain higher aliphatic acids,61 pnaphtho1,62 phenols generally,63and o-dihydroxyphenols in particu3ar764 for certain diamino- andnit roamino - di phen y 1 sul p hides , 65 gl y oxaline derivatives and tyro -sine,66 thiolglyoxalines,67 morphine,68 adrenaline,69 salicylic acidand salol, 7O phenyl o-aceto~ybenzoate,~~ tannin, gallic acid, andpyrogallol, 72 quinones,73 aromatic amines 7* and the toluidines inparticular, '5 ephedrine,76 cystine,77 eugenol and clove carbo-57 A.M. Schwartz and J. R. Johnson, J . Amer. Chem. Soc., 1931,53, 1063;5 8 H. W. Underwood, jun., 0. L. Baril, and G. C. Toone, ibid., 1930, 52,59 F. Feigl and K. Weisselberg, 2. anal. Chem., 1931, 83, 93; A., 638;6o E. Tschirch, Oesterr. Chem.-Ztg., 1931, 34, 38; A., 601; D. Xruger and61 L. Ekkert, Pharm. Zentr., 1931, 72, 228; A., 710.62 G. de Haas, Pharm. Weekblad, 1931, 68, 29; A., 347.63 C. D. Leake, Proc.SOC. Exp, Biol. Med., 1930, 28, 148; A., 856; V. E.Levine, J . Amer. Pharm. ASSOC., 1931, 20, 537; A., 972 ; &I. Franqois and(Mlle.) L. Seguin, Bull. Soc. chim., 1931, [iv], 49, 650; A., 972; L. Rosen-thaler, Pharm. Ztg., 1931, 76, 8 8 8 ; A., 1174.A., 597.4087; A., 1930, 1554.S . L. Malowan, ibid., 84, 406; A., 1078.E. Tschirch, Mikrochem., 1930, 8, 337 ; A., 335.64 J. H. Quastel, Analyst, 1931, 56, 311 ; A., 856.G5 H. H. Hodgson and W. Rosenberg, J . Soc. Dyers Col., 1930, 46, 267;A., 84.G6 E. Gebauer-Fulnegg, 2. physiol. Chem., 1930, 191, 222; A., 1930, 1605;J. A. Shnchez, Semana mdd., 1930, I , 1579; A., 108.6 7 G. Hunter, J., 1930, 2343; A., 1930, 1596.O 8 F. Bamford, Analyst, 1931, 56, 586; A., 1312; L. Rossi, Anal.Farm.69 B. Azzolini, Boll. cJzim.-farm., 1931, 70, 665; A., 1315.70 L. Ekkert, Pharm. Zentr., 1930, 71, 744; A., 88.71 H. Szancer, ibid., 1931, 72, 68; A., 351.72 M. N. A. de Celsi and S. A. Celsi, AnaZ. Farm. Bioquim., 1931, 2, 56;73 R. Craven, J., 1931, 1605; A., 972.74 I. de Paolini, Atti R. Accad. Sci. Torino, 1930, 65, 201 ; A., 638.75 W. H. Patterson, J., 1930, 2401 ; A., 1930, 1605.7 6 W. H. Hartung, F. Crossley, and J. C. Munch, J . Pharm. Chim., 1931,[viii], 13, 474; A., 724; J. Sivadjian, ibid., 1930, 12, 266; A., 1930, 1460;idem, ibid., 1931, 14, 61 ; A., 1079.Bioquim., 1930, 1, 106; A., 1319.A., 1174.7 7 J. A. SAnchez, Semana mt?d., 1930, 11, 31 ; A., 1930, 1563.78 H. Szancer, Bull. Sci. pharmacol., 1929, 36, 611 ; A., 1930, 1605203 ANALYTICAL CHEMISTRY.hydrates and related benzene, naphthalene, eft-,p-benzoquinone, and quinoline,go and the aitro-group.slThe Scott-Wilson reagent for acetone and acetaldehyde can bemade specific for the Micro-crystallographic data aregiven for mesaconic acid and certain of its derivatives; 83 thefluorescent properties of umbelliferone enable its formation frommalic acid and resorcinol to serve as specific tests for these sub-stance~.~* Differentiation of cyclic monophenols and monoaminesfrom polyphenols and polyamines is effected by means of phospho-tungstic and phosphomolybdic reagents.85 Triketohydrindenehydrate is not a trustworthy reagent for the products of proteinhydrolysis.86 The action of iodine and bromine on unsaturatedbarbituric acid derivatives in bicarbonate solution is described ; 87" veronalides " are diagnosed micro-crystalloscopically.88Alkaloids are classified in nine groups according to their sensitivitytowafds precipitating agents, their solubility in water and thebasic strength of the free alkaloids; 89 a tabulation is made of themicrochemical reactions of 78 alkaloids with a number of reagents.90Limiting concentrations for the micro-precipitation of alkaloids bysodium alizarinsulphonate are recorded ; 91 sulphonic acids of otheranthraquinone derivatives form crystalline precipitates with organicbases.92 Microchemical methods are described for the detectionof strychnineJS3 I-ephedrine and ephet~nine,~~cytisine,~~ echinopsine,96nicotineJS7 colchi~ine,~~ piperineJ99 and choline.1 The formationJ.S. Hepburn and M. Lazarchick, Amer. J. Pharm., 1930,102,560; A., 69.P. K. Bose, Analyst, 1931. 56, 504; A., 1148.8o L. Ekkert, Pharm. Zentr., 1931, 72, 51; A., 375..82 L. Klinc, Arhiv Hemiju, 1931, 5, 212; A., 1273.83 13. €3. Mottern and G. L. Keenan, J . Amer. Chem. SOC., 1931, 53, 2347 ;84 L. Columbier, Ann. Palsif., 1931, 24, S9; A., 698.8 5 A. Marenzi, Anal. Farm. Bioquim., 1930, 1, 99; A., 375.86 H. Gardner, Lancet, 1930, ii, 525; A., 972.*' J. Bougault and J. Guillon, Compt. rend., 1931, 193, 463; A., 1308.8 8 G. Denighs, Mikrochem., 1931, 9, 316; A., 966.ee C. C. Fulton, J. Assoc. Off. Agric. Chem., 1930, 13, 491 ; A., 243.J. F. H. Amelink, Pharm. Weekblad, 1931, 68, 159, 211, 221; A., 504.91 L.Rosenthaler, Apoth.-Ztg., 1930, 45, 638; A., 375.s 2 W. Zimmermann, 2. physiol. Chem., 1930, 188, 180; 189, 155; 192,93 V. D. Gnesin, Farm. Zhur., 1930, 293; A., 1079.94 L. Rosenthaler, 2. anal. Chem., 1931, 86, 61 ; A., 1319.s5 G. Klein and E. Farkass, Oesterr. Bot. Z., 1930, 79, 107; A., 213.96 G. Klein and F. Schusta, ibid., p. 231; A., 639.9 7 G. Klein and E. Herndlhofer, ibid., 76, 222; A., 639.# * G. Klein and G. Pollauf, ibid., 1929, 78, 251 ; A., 778.SY G. Klein and M. Krisch, ibid., p. 257; A., 778.G. Klein and A. Zeller, ibid., 79, 40; A., 778.A., 1036.124; A., 1930, 941, 1170, 1605FOX AND ELLIS: 204of the substance responsible for the thalleioquinine reaction isretarded by a decrease in p,.2Reactions of choline and le~ithin,~ creatine and ~reatinine,~a l a n i ~ ~ e , ~ antipyrine and pyramidone,6 narceine,' dulcine,s andmezcaline are given.Sodium nitroprusside gives colour reactionswith a variety of organic cornpounds.lO Iodine tetrachloride isused for the microchemical identification of a number of alkaloids ; l1p-toluenesulphonic acid is suggested as condensing agent for thedetection of alcohols by the odour of their esters, and isopropylalcohol can be recognised in presence of ethyl alcohol by its reactionwith protocatechualdehyde. l2An account is given of the application of micro-sublimationmethods to the identification of small quantities of materials, l3and an apparatus described for the extraction of benzoic and otheraromatic acids.l4&uantitative.-Sulphur is eliminated in direct combustions forcarbon by a plug of asbestos upon which red lead has been~ub1imed.l~The extent to which combustion tubes and the materialsused in organicelementary analysis yield water on ignition has been investigated ; l6advantages are claimed €or copper tubes in corn bust ion^.^^ Investig-ations on the elementary analysis of organic compounds may be re-viewed under the following heads : carbon and hydrogen,18nitrogen, l9J. Eisenbrand, Arch. Phwm., 1931, 269, 65; A., 639.J. A. Shchez, Xemana ma., 1930, I, 1416; A., 75.Idem, ibid., 11, 616; A., 246.Idem, ibid., 1931, I, 651 ; A., 1042.M. Ribitre, J. Phurm. Chim., 1930 [viii], 12, 444; A., 99. ' J. A. Sanchez, Anal. Farm. Bioquim., 1931, 2, 68; A., 1174.Idem, ibid., p.63; A., 1174.L. Rosenthaler, Pharm. Ztg., 1931, 76, 653; A., 1318.lo T. Pavolini, Boll. chim.-farm., 1930, 69, 713; A., 1930, 1605.l1 L. Rosenthaler, Pharm. Ztg., 1931, 76, 524; A., 857.l2 Idem, ibid., 775; A., 971.l3 A. Chalmeta, Anal. Pis. Quim., 1930, 28, 1407; A., 246.l4 A. N. Leather, Analyst, 1931, 56, 299; A., 856.l5 W. H. Blatchley, I d . Eng. Chem. (Anal.), 1931, 3, 13; A., 503.lG J. Lindner, Ber., 1931, 64, [B], 1560; A., 1078.N. Klatschin, 2. anal. Chem., 1930, 82, 133; A., 1930, 1604.H. Lieb and H. G. Kraineck, Mikrochem., 1931, 9, 367; A., 971 ; J. B.Niederl and J. R. Meadow, ibid., p. 350 ; A., 971 ; A. Verdino, ibid., p. 123 ;A., 638 ; A. Friedrich, ibid., p. 20 ; A., 374 ; M. Furter, ibid., p.27 ; A., 374 ;F. Herder, ibid., 1930, Emich Festschr., 148; A., 107; E. P. Griffing and C.L. Alsberg, J. Amer. Chem. Xoc., 1931, 53, 1037; A., 638; E. Stansfield andJ. W. Sutherland, Canadian J. Res., 1930, 3, 318; A . , 1930, 1604.W. J. Saschek, I n d . Eng. Chern. (Anal.), 1931, 3, 198; A., 700; N. %I.Stover and R. B. Sandin., ibid., p. 240; A., 1024; W. F. Allen, ibid., p. 239;A., 1024 ; 0. R. Trautz and J. B. Niederl, ibid., p. 151 ; A., 752 ; J. J. Rutgers,Cornpt. r e d . , 1931,193, 51 ; A., 1024; J. Schmidt and W. Maier, Ber., 1931ANALYTICAL CHEMISTRY. 205halogensY20 and phosphorus.21 A volumetric method of deter-mining methoxyl and ethoxyl groups is described 22 which mayalso be used on the micro-scale; z3 modifications are made inthe micro-Zeisel process to render i t applicable to polymethoxy-compound^.^* The Fuchs-Hunter-Edwards method for determiningcarboxyl groups is adapted for micro-w0rk.~5 The use of benzyl-alcoholic alkali is recommended for the determination of acetylgroups in substituted acetamides.26 Some errors in analyticalbromination have been investigated, and a process is detailed forthe measurement of organic unsaturation.27Oxidation of small amounts of ethyl alcohol with chromic acidgives results comparable with those obtained by the specific gravitymethod; 28 a modified micro-Zeisel process has been applied tothis alcoh01.2~ Reaction with ethyl formate and ethoxide to givesodium formate serves to prepare anhydrous alcohol and to deter-mine the water content of alcoh01.~0 A n account is given of theuse of Ilosvay’s reagent for the determination of traces of acetylene.31Reaction of formaldehyde or hexamethylenetetramine with methoneshould be effected in neutral solution.32 Modifications of existingmethods are made for the determination of solid saturated33 and64, [B], 778; A ., 752; F. Govaert, Natuurwetensch. Tijds., 1931, 13, 127;A., 856; idem, Mikrochem., 1931, 9, 338; A., 971; idem, Ann. Chim. analyt.,1931, [ii], 13, 229; A., 1142; J. C. Harral, Analyst, 1931, 56, 527; A., 1174;M. Weizmann, J. Yofe, and B. Kirzon, 2. physiol. Chem., 1930,192, 7 0 ; A.,1930, 1604; A. C. Anderson and B. N. Jensen, 2. anal. Chem., 1931, 83,114; A., 638; 0. R. Trautz, Mikrochem., 1931, 9, 300; A., 971.2o B.Bobradski, Rocz. Chem., 1931, 11, 301; 2. anal. Chem., 1931, 84,225; A., 856; F. Schulz, Coll. Czech. Chem. Cornm., 1931, 3, 281; A., 945.21 W. C. Davies and D. R. Davies, J . , 1931, 1207; A., 856..32 F. Viebock and A. Schwappach, Ber., 1930, 63, [ B ] , 2818; A , , 107.23 F. Viebock and C. Brecher, ibid., p. 3207; A., 246.?* (Miss) G. M. Ware, Mikrochem., 1930, 8, 352; A., 374.25 S. Tsurumi and Y. Sasaki, Sci. Rep. 176hoku Imp. Univ., 1930, 19, 681 ;A . , 504.26 S. Sabetay and J. Sivadjian, J. Pharm. Chim., 1931, [viii], 13, 530; A.,856.27 H. M. Buckwalter and E. C. Wagner, J. Amer. Chem. SOC., 1930, 52,5341 ; A., 193.28 S. G. Liversedge, Analyst, 1931, 56, 595; A., 1267; M. Nicloux, Compt.rend., 1931, 192, 985; A., 752; idem, Bull.SOC. Chim. biol., 1931, 13, 857;A., 1327.2D J. B. Niederl and B. Whitman, 2. anal. Chem., 1931, 86, 65 ; A., 1318.30 F. Adickes, W. Brunnert, and 0. Lucker, Ber., 1930, 63, [B], 2753; A.,61.31 W. Riese, 2. angew. Chem., 1931, 44, 701; A., 1318; see also E. Czak6,ibid., p. 388; A., 819; and E. Pietsch and A. Kotovski, ibid., p. 388 ; A., 819.32 V. Ionescu and C. Bodea, Bull. SOC. chim., 1930, [iv], 47, 1408; A . , 335.33 T. P. Hilditch and J. Priestman, Analyst, 1931, 56, 354; A., 935206 FOX AND ELLIS:of solid unsaturated34 fatty acids, and for Okey’s method forchole~terol.~~ Methods involving the use of iodine monochlorideor bromide are found to be unsuitable for the determination ofthe iodine value of cholesterol owing to substitution ; Kaufmann’smethod is preferred, with that of Rosenmund and Kuhnhenn assecond choice.36 A quantitative separation of saturated and un-saturated sterols depends on the fact that cholesterol dibromideis not precipitated by digitonin.37 Work on the oxidation of sugarsby iodine in presence of alkali,3* by ferri~yanide,~~ and by cupro-potassium carbonate solutions 4O has been extended.A colori-metric method with acid molybdate is applied to laevulose in presenceof certain other sugars ; 41 some factors governing the fermentationof polysaccharides are discussed.42The humic acid content of dilute solutions is ascertained bypermanganate oxidation under prescribed condition^.^^ The com-position of the phospho- and silico-tungstates of choline and alliedbases has been rec0rded.~4 The pDH at which phosphotungstateprecipitates of certain bases appear depends largely on the con-stitution of the base;45 reaction between nicotine and silico-tungstic acid, applied volumetrically, does not appear to be stoicheio-metric.46 Values of pH a t the end-point of the neutralisation ofalkaloid bases have been deduced, and suitable indicators for thetitration selected ; 47 colorimetric methods are described for mor-34 L.V. Cocks, B. C. Christian, and G. Harding, Analyst, 1931, 56, 368;35 M. Yasuda, J . Biol. Chem., 1931, 92, 303; A., 1318; M. E. Turner, ibid.,36 H. Werner, 2. Unters. Lebensm., 1931, 61, 331; A., 1318.37 R. Schonheimer, 2. physiol. Chem., 1930, 192, 7 7 ; A., 1930, 1616.35 G.M. Kline and S. F. Acree, Ind. Eng. Chem. (Anal.), 1930, 2, 413; A.,1930, 1560; Bur. Stand. J . Res., 1930, 5, 1063; A., 199.39 A. C. Hulme and R. Narain, Biochem. J., 1931, 25, 1051; A., 1274;E. M. Widdowson, ibid., p. 863; A., 1102; 0. Lehmann, Planta, 1931, 13,575; A . , 1038.40 H. A. Schuette and J. N. Terrill, J . Amer. Chem. SOC., 1930, 52, 4960;A . , 199.41 H. Bredereck, Ber., 1931, 64, [B], 1730; A . , 1039.42 E. Schmidt, M. Atterer, and H. Schnegg, Cellulosechem., 1931, 12, 235;43 D. J. W. Kreulen, Brennstoff-Chem., 1031, 12, 265; A., 1148.44 L. Lematte, G. Boinot, E. Kahane, and (Mme.) M. Kahane, J . Pharm.Chim., 1931, [viii], 13, 371; A., 606; Cornpt. rend., 1930, 191, 1130; A.,338.A., 935.p. 495; A., 1174; see R.Olrey, ibid., 1930, 88, 367; A., 1930, 1303.A., 1038.45 R. A. Peters, Biochem. J., 1930, 24, 1852; A., 374.46 B. Kasansky, 2. anal. Chem., 1931, 83, 107; A., 639.47 E. B. R. Prideaux and F. T. Winfield, Analyst, 1930,55,561; A., 246;compare also F. Reimers, Dansk Tidsskr. Farm., 1931, 5, 42; A., 752ANaLYTICAL CHEMISTRY. 207phine, heroine, and physo~tjgmine,~8 cryogenin,@ tryptophan,50strychnine, emetine, cinchonine, and quinine,51 cystine 52 and~ y s t e i n e . ~ ~ Serine in hot alkaline solution gives ammonia, glycine,alanine, and oxalic and lactic acids.54 The precipitate formedfrom choline with excess of gold chloride is stable to concentrationand can be washed with water.55 In dilute alcohol-ether solutionnovocaine, but not cocaine, is precipitated by picric acid; 56 amixture of chloroform and isopropyl alcohol is recommended forthe extraction of morphine from its aqueous s~spension.~~ Con-ditions are prescribed for the quantitative saponification of thelactone group in narcotine and santonin.58 An iodo-gasometricmethod for determining cysteine (or, after reduction, cystine) isdescribed.59Pyramidone is quantitatively precipitated by an excess of mercuricchloride ; antipyrine is precipitated also, but not quantitatively.60Mercurimetric methods have applied to citrates, salicylates, andbenzoates.61 Verley , and Bolsing’s method has been applied tothe determination of the hydroxyl group in castor oil and variousphenols.62 Determination of phenylhydrazine gasometrically isapplied to the evaluation of the carbonyl group of ketones andaldehydes; 63 the method involving formation of iodoform fromthe COMe group in acetone can be extended to many ketones con-taining this group.64Conditions for the alkalimetric titration of 2 : 4-dinitrophenol48 L.David, Pharm. Ztg., 1931, 76, 706; A., 972.50 T . Ruemele, 2. anal. Chem., 1931, 84, 81; A., 1079. I51 C. A. Rojahn and R. Seifert, Arch. Pharm., 1930, 268, 499; A., 1930,1605.52 M. X. Sullivan, U.S. Pub. Health Rep. Suppl., 1929, No. 78; M. X.Sullivan and D. B. Jones, ibid., No. 82; M. X. Sullivan and W. C. Hew,ibid., No. 86; A., 1930, 1604.G. Denighs, Bull. Pharm. Soc. Bordeaux, 1930, 68, 49, 51; A., 604.53 Idem, ibid., Reprint No. 1450; A., 831.54 F. S. Daft and R.D. Coghill, J . Biol. Chem., 1931, 90, 341; A., 638.5 5 L. Pincusson and E. von Heyden, Biochem. Z., 1931, 234, 484; A.,56 F. Weiss, Apoth.-Ztg., 1930, 45, 724; A., 375.5 7 H. Baggesgaard-Rasmussen and S. A. Schou, Arch. Pharm., 1930, 268,5 8 A. P. Snesarov, J . Chem. Ind. Russia, 1931, 8, 161; A . , 752.5B H. D. Baernstein, J . Biol. Chem., 1930, 89, 124; A., 108.6o R. Machtou, J . Pharm. Chim., 1931, [viii], 13, 329; 4., 639.61 A. Ionescu-Matiu and (Mme.) Popesco, ibid., 14, 54; A., 1079.62 S. Marks and R. S. Morrell, Analyst, 1931, 56, 428; A., 1035; Hupp-63 S . Marks and R. S. Morrell, Analyst, 1931, 56, 508; A., 1149.g4 V. Cuculescu, Bul. Pac. Stiilzte Cernauti, 1928, 2, 143 ; A., 752.829.673; A., 371.mann, Pharm. Ztg., 1931, 76, 113; A., 752208 FOX AND ELLIS:are prescribed ; 65 cuprammonium sulphate precipitates picricacid as a picrate which may be weighed.66 Trinitrotoluene, butnot trinitroxylene, is converted by p-nitrosodimethylaniline inpresence of pyridine and a trace of iodine into the azomethinecompound which is weighed.67 Reduction with titanous chlorideis applied on a micro-scale to various aromatic nitro-compounds.68Examination has been made of the methods of analysing cres01s.~~Physical Methods.There has been a discussion on titration in Wood's light.'OCalcium oxalate is considered unsuitable for nephelometry, 71 whichhas been applied to the determination of sulphates.72Methods involving extinction coefficients have been applied tobenzene in alcohol 73 and to t h i ~ c y a n a t e .~ ~ Photoelectric methodsare used for dilute solutions generally 75 and for certain hydroxy-acids. 76 The copper salts of the amino-acids show characteristicabsorption curves. 77 Partition constants for pairs of fatty acidsbetween ether and water have been ascertained ; 78 camphor affectsthe surface tension of a dilute alcohol solution proportionately. 79An " isopyknoscopic " method can be used for ascertaining theconcentration of solutions of pure compounds. Radiometricmicroanalysis is used in sulphide determinations and oxidimetry. *lAtmospheric ozone is determined by an optical method; s2 the6 5 A. Suchier, 2. anal. Chem., 1931, 85, 434; A., 1318.6 6 M. Franqois and (Mlle.) L. Seguin, Ann. Palsif., 1930, 23, 481 ; A ., 107.67 S. Secareanu, Ber., 1931, 64, [B], 834; A., 752.6 8 S . Maruyama, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1931, 16, 196;60 P. Dumont, J . Pharm. Belg., 1930, 12, 1, 21, 41, 65, 87; A., 375.70 A. G. Nasini and P. de Cori, Atti I I I Cong. Naz. Chim., 1929, 668; A . ,924.71 A. I. Polinkovski, Trans. State Inst. Test. Building Mat., 1929, No. 27,11; A., 1259.72 Chatron, J. Pharm. Chim., 1931, [viii], 13, 321; A., 586; S. W. Pamand W. D. Staley, I d . Eng. Chem. (Anal.), 1931, 3, 66; A., 451.73 G. Gr6h and E. Faltin, Magyar Chern. Pol., 1930, 36, 156; A., 638.71 C. Urbach, Biochem. Z., 1931, 237, 189; A., 1257.7 5 M. Matsui and T. Noda, J . SOC. Chem. Ind. Japan, 1930, 33, 517; A.,7 6 A. S. Williams, R. H.Muller, and J. B. Nieder!, Mikrochem., 1931, 9,7 7 H. Ley and B. Arends, 2. physiol. Chem., 1930,192, 131 ; A., 1930, 1604.C. 1%. Werkman, Iowa State Coll. J . Sci., 1930, 4, 459; A., 374.79 M. L. Nichols and A. Stubblefield, 2. anal. Chem., 1931,86,30; A., 1318.A. Del Campo, C. Nogareda, and M. G. de Celis, Anal. Pis. Quim., 1931,81 R. Ehrenberg, Mikrochem., Emich Festschr., 1930, 120; A., 1930, 1542.s2 A. I. Duninowski, Compt. rend., 1930, 191, 859; A . , 55.A., 1318.325.269; A., 936.29, 386 ; A., 924ANALYTICAL CHEMISTRY. 209pressure at which phosphorus starts to glow is governed by theproportion of hydrocarbon in the air or oxygen.83 Mixtures maybe analysed by monochromatic transmission.84 A method forreducing the errors of colorimetric determinations is recorded.85X-Ray methods have been applied quantitatively to certainrare-earth mixtures, 86 to copper-silver and -zinc alloys, 87 to certainother binary alloys,88 and qualitatively to distinguish betweenmagnesite and dolomites.89 Spectro-analytical methods are de-scribed for the determination of traces of mercury,w of strontiumin calcium,g1 of traces of nickel and chromium,92 of binary alloys,93of various gases,9* of metals in s0lution,~5 and qualitatively fortraces of impurities in metals ; 96 a means of increasing the accuracyof quantitative emission spectral analysis is indi~ated.~'EZectroEytic.-Small electrodes are described for qualitativemicroelectrolysis.98 Several papers deal with the electro-analyticalseparation of copper.99 Lead is deposited free from antimonyfrom alkaline tartrate solutions under certain conditions.lThe series of polaro-graphic studies with the dropping-mercurycathode have been continued.283 J.Tausz and H. Gorlacher, 2. anal. Chem., 1931, 83, 81; A . , 587.84 M. Barnard and P. MeMichael, I d . Eng. Chem. (Anal.), 1930, 2, 363;8 5 F. F. Hahn and R. Klockmann, 2. angew. Chem., 1930,43,993; A., 54.86 P. Giinther, A. Kotovski, and H. Lehl, 2. anorg. Chem., 1931, 200, 287;H. Terrey and E. G. V. Barrett, J. Physical Chem., 1931, 35, 1156; A.,G. R. Fonda and G. 13. Collins, J. Amer. Chem. SOC., 1931, 53, 113; A.,F. Halla, -Monatsh., 1931, 57, 1 ; A , , 453.W. Gerlach and E..Schweitzer, 2. anorg. Chem., 1931, 195, 255; A., 328.A., 1930, 1541.A., 1261.702.328.91 K.Ruthardt, ibid., p. 15; A., 327.92 A. J. de A. Gouveia, Rev. Chim. pura appl., 1930, 5 , 41; A., 1143.93 G. Guzzoni, Atti 111 Cong. Naz. Chim., 1929, 636; A., 924.94 B. de la Roche, Bull. SOC. chim., 1930, [iv], 47, 1326; A., 185.95 F. Twyman and C. S. Hitchen,Proc. Roy. SOC., 1931, [A], 133,72 ; A., 1260.96 L. h e y , Compt. r e d . , 1930, 191, 1049; A., 187; H. E. Redeker and9 7 G. Scheibe, C. F. Linstrom, and 0. Schoettler, 2. angew. Chem., 1931,g 8 H. J. Brenneis, Mikrochem., 1931, 9, 385; A., 924.gS H. Holemann, 2. anal. Chem., 1930, 81, 161; A . , 57; idem, ibid., 82,273; A., 187; T. L. Kelly and J. J. Molloy, J. Amer. Chem. SOC., 1931, 53,1337; A . , 702; C. Zbinden, Bull. SOC. Chim. biol., 1931, 13, 36; A., 701;N.H. Furman, Ind. Eng. Chem. (Anal.), 1931, 3, 217; A., 701.P. A. Leighton, J. Amer. Chern. SOC., 1930, 52, 4169; A., 1930, 1546.44, 145; A , , 924.E. M. Collin and H. J. S. Sand, Analyst, 1931, 58, 90; A., 588.J. Heyrovskg and V. Nejedlg, Coll. Czech. Chem. Comm., 1931, 3, 126;A., 451; K. Suchy, ibid., p. 364; A., 1025; J. Prajzler, did., p. 406; A.,1261 ; J. Heyrovsk;j, Arhiv Hemiju, 1931, 5, 162; A., 12572 10 FOX AND ELLIS:Potentiometric.-Methods are described for the titration of leadwith ~hromate,~ of silver i ~ d i d e , ~ of silver, cupric, and mercuricions with c~balt~icyanide, of iridium,6 of bivalent platinum,' ofuranium,' of zinc,9 of ferric and dichromate ions with uranoussulphate,lo of ferrocyanide and nitrite mutually,ll of Caro's acidand hydrogen peroxide,l2 of carbonate,13 of phosphoric acid,14of cystine and cysteine,ls of certain drugs l6 and alka1oids,l7 ofpiperidine in mixture with pyridine and its homologues, l8 andof amino-nitrogen.lg The point of inflexion on the titration curveof zinc chloride with sodium hydroxide occurs before two equivalentsof the alkali have been addedm20The value of two solid electrodes in cases involving titrationswith ferrocyanide and with silver nitrate,21 and some factors con-cerned in differential titration 22 have been studied.Conduct0metric.-The titration of sulphate and ofmolybdenum, tungsten, and thallium,24 the influence of smallamounts of carbonic acid on the titration of acids and bases,25R. W. Gelbach and K. G. Compton, Ind. Eng. Chem. (Anal.), 1930, 2,397; A., 1930, 1545.* E. Lange and R. Berger, Z. Elektrochem., 1930, 36, 9SO; A., 186.L. Czaporowski and J. Wierciliski, Rocz. Chem., 1931, 11, 95; A., 588.S. C. Woo and D. M. Yost, J . Amer. Chem. Soc., 1931, 53, 884; A., 590.0. Stelling, Svensk Kem. Tidskr., 1931, 43, 130; A., 814.D. T. Ewing and (Mrs.) M. Wilson, J. Amer. Chem. Soc., 1931, 53,2105 ;A., 927; N. H. Furman and I. C. Schoonover, ibid., p. 2561; A., 1026; M.A. Luyckx, Bull. SOC. chim. Belg., 1931, 40, 269; A., 1026.E. Brennecke, 2. anal. Chem., 1931, 86, 175; A., 1260.lo E. H. Ducloux, Rev. Pac. Cienc. quim., L a Plata, 1930, 7, 11, 97; A.,11 J. V. Romb, Anal. Pis. Quirn., 1930,28, 1045; A., 1930, 1542.l2 E. Muller and Q. Holder, 2. anal. Chern., 1931, 84, 410; A., 1023.l3 A. Ringbom, ibid., p. 161; A., 812.l4 A. Sanfourche, Compt. rend., 1931, 192, 1225; A., 812.l5 K. Yamazaki, J . Biochem. Japan, 1930, 12, 207; A., 374.l6 L. Maricq, Bull. SOC. chim. Belg., 1931, 40, 361; A . , 1318.1 7 Idem, ibid., 39, 496; A., 375; M. L. Holt and L. Kahlenberg, J. Amer.1s A. Travers and Franquin, Compt. rend., 1930, 191, 1340; A., 375.1025.Pharm. ASSOC., 1931, 20, 11; A., 375.J. Roche and (Mme,.) A. Roche, Bull. SOC. Chim. b i d , 1931, 13, 835; A.,1318.20 M. Prytz, 2. anorg. Chem., 1931, 200, 133; A., 1260.2 l J. A. Atanasiu and A. J. Velculesco, 2. anal. Chem., 1931, 85, 120; A.,z2 D. A. MacInnes and I. A. Cowperthwaite, J . Amer. Chem. SOC., 1031, 53,23 I. M. Kolthoff and T. Kameda, Id. Eng. Chem. (Anal.), 1931, 3, 129;24 G. Jander, 2. angew. Chem., 1930, 43, 930; A., 1930, 1548.25 W. Poethke, 2. anal. Chm., 1931, 86, 45; A., 1256.1260.555 ; A., 450.A., 699ANALYTICAL CHEMISTRY. 211and the titration of organic acids and bases in benzene 26 have beenstudied. For binary mixtures of formic, acetic, propionic, andn-butyric acids, the antilog of K x lo3 is a linear function of thecomposition.27 On account of ready oxidation in alkaline solutionpreventing the use of ordinary indicators in the determination ofthe acetyl group in acetylated derivatives of polyhydric phenols,the conductometric method is utilised.28 J. J. Fox.B. A. ELLIS.26 V. K. LaMer and H. C. Domes, J . Amer. Chem. SOC., 1931, 53, 888;27 E. I. Fulmer, E. E. Moore, and R. L. Foster, J . Physical Chem., 1931,28 C. Torres, A. S. Capuchino, and L. Socias, Anal. Pis. Quim., 1930, 28,A., 584.35, 1227; A., 1078.694; A., 1930, 1605