creasing acidity. This behaviour is probably to be ascribed to the existence of a complex acid.
M. S. Bu r r.
F orm ation of a carbide, Fe2C, by reduction of iron oxid e w ith carbon m on oxid e at a low er tem p eratu re. W. Gl u u d, K. V. Ot t o, and H.
Ri t t e r (Ber., 1929, 62, [5], 2483—2485).—If ferric oxide is heated in a current of carbon monoxide at 275°, reduction to triferric tetroxide rapidly occurs followed by simultaneous deposition of carbon and formation of carbide. If the percentage of carbon is plotted against the time, a graph is obtained of which the latter portions are rectilinear, showing that deposition of carbon is proportional to the time and independent of the nature and amount of substrate.
Extrapolation of the curve indicates the existence of a carbide, Fe2C. Confirmation is found by study of the volatilisation of carbide carbon in hydrogen at 275°, which is arrested at a point when the loss of carbon corresponds exactly with the formula Fe2C.
If a decarbonised product is again treated with carbon monoxide for a shorter period than is required for the production of the carbide, Fe2C, and then with hydrogen, almost exactly only the newly-added carbon is removed.. If, however, more carbon is deposited than corresponds with the compound Fe2C, only so much of it is volatilised as corresponds with Fe2C.
The experimental results of Fischer and Balir (Ges. Abhand. Kenntn. Kohle, 8, 265) coincide with those of the authors, and, if their graphs are treated as indicated above, the existence of the carbide Fe2C (instead of Fe3C4) is demonstrated.
H. Wr e n.
O xidation and reduction of silica tes of iron b y g a ses. B . Bo g it c h (Compt. rend., 1929, 189, 581—583).—The method previously employed (this vol., 400) has been used to investigate the oxidising or reducing effects at 1300° of oxygen, nitrogen, carbon dioxide, carbon dioxide-monoxide mixtures, hydrogen, and illuminating gas (containing methane) on iron silicates. The colours of the silicates were found to vary in intensity with the percentage of iron (0-1—1 0%), but it is considered that they are made up of combinations in varying proportions of the two yellow and two blue silicates. There are no silicates corresponding with the oxides Fe203 or Fe30 4, but one of the blue compounds corresponds with a sub
oxide. J. Gr a n t.
A q u op en tam m in o- and d iaquotetram m ino- cob altic su lp h ates. F. Jo b and L. 0 . Ta o (Compt.
rend., 1929, 189 , 641—642).—Examination by Schreinemakers’ method of a solution of aquo- pentamminocobaltic sulphate to which sulphuric acid has been added shows that for concentrations of 0—0-5 mol. of acid per litre the solid phase is the salt itself, and for 2—4-5 mois, of acid per litre it is [Co(NH3)5H20 ](S 04),H S04,H20 in the cold and at 56°
[C0(NH3)5S 04jH S04,2H20 . For other concentrations the tie-lines are not concurrent, although nearly so for concentrations of 4-5—8-5 mois, of acid per litre.
A similar method applied to
diaquotetrammino-cobaltic sulphate indicates the formation at the ordinary temperature of the salts
[Co(NH3)5(H20 )2]2(S04)3,2-5H,0, [Co(NH3)4(H2O)2]7(SO4)i0HSO4, and [Co(NH3)4(H20 )2](S04)H S04. C. A. Si l b e r r a d.
N ew cob altites of th e sp in el type. S. Ho l g e r s- s o n and A. Ka r l s s o n (Z. anorg. Chem., 1929, 183, 384—394).—A series of cobaltites of the type R0,Co203 (where R is Cu, Mg, Zn, Mn, Ni) has been prepared by mixing solutions of cobalt nitrate and the nitrate of the metal, evaporating to dryness, and heating the product to 800—850°. The X-ray spectra of the products, examined by the D ebye- Scherrer method, were all of the spinel type. The unit cell contains eight molecules. The oxide Co304
prepared in three different ways gave similar spectra and is therefore CoO,Co20 3. It is possible that some mixed crystal formation occurs; e.g., in manganese cobaltite the bivalent manganese may be partly replaced by bivalent cobalt and tervalent cobalt by tervalent manganese, giving (Mn,Co)0,(Mn,Co)20 3.
J. A. V. Bu t l e r.
D ouble sa lts. XVIII. A m m in o -o x a la tes. G . Sp a c u and O. Voicu (Bui. Soc. Stiinte Cluj, 1928, 4, 154— 164; Chem. Zentr., 1929, i, 3080).—The follow
ing complex salts are described : K2[Ni(C204)2(H ,0)2] ,H ,0 ; K2[Ni(C204)2(C X *C H2-NH2“)2],2H O ; K2Ni(C204)2 en3,3H20 ; K,[Co(C204)2(H20 )2],4H20 ; K2[Co(C204)2(C6H5-CH2-NH2)2],2H2O.
A. A. El d r i d g e.
D ouble sa lts. X IX. A m m in e s of double b rom id es. G . Sp a c u and J. Di c k (Bui. Soc.
Stiinte Cluj, 1928, 4, 187—210; Chem. Zentr., 1929, i, 3080—3081).—Three groups of compounds were differentiated according to the solvents used in their preparation : (1) The compounds (Bzd=benzidine) [MnBzd6][SnBr6],2H20 ; [NiBzd„][SnBr6],8 or 4H20 ; [CoBzd6][SnBrs],4 H ,0 ; (2) the compounds
[MnBzd5(C0Me2)][SnBr6],2 H ,0 ; [NiBzd5(C0Me2)][SnBrfi],8H20 ;
[CoBzd5(C0Me2)],6H20 ; (3) [NiBzd5(O H5N)][SnBr6],8H20 ;
[MnBzd5(C5H5N)][SnBr5(OH)];
[CoBzd5(C5H5N)][SnBr5(0H )],5H20 ; [NiBzd5(C5H5N)][SnBr5(0H)],4H20.
A. A. El d r i d g e.
A p p lication s and lim its of em issio n sp ectro- grap h ic a n aly sis. G . Sc h e i b e (Z. angew. Chem., 1929, 42, 1017— 1022).—The principles and practice of the quantitative spectrographic analysis of alloys are discussed, and the special value of this method for ascertaining the purity of metallic copper, lead, zinc, aluminium, and magnesium is emphasised.
H . F. Ha r w o o d.
S eg reg a tio n of an alysed sa m p les. G . F.
Sm i t h, L. V. Ha r d y, and E. L. Ga r d (Ind. Eng.
Chem. [Anal.], 1929, 1, 228—230).—Mixtures of arsenic trioxide with mercuric oxide or potassium sulphate, ferric oxide and silica, and ferrosoferrio oxide and magnesia were filled into a brass column and subjected to mechanical jarring for 90 h rs.; in the last case the difference in density was artificially augmented by means of an electromagnet. Samples
1410 B R IT ISH CHEMICAL ABSTRACTS.— A .
taken from different parts of the column were then analysed. The results indicate that mixtures of materials of different densities if once mixed to uniformity following grinding to pass a 2 0 0-mesh sieve cannot he segregated by jarring or storage under vibration, irrespective of the actual densities of the components. Hence in referee analyses of supposedly identical samples if different analysts disagree the fault cannot be ascribed to segregation of the samples, provided that these have been ground to pass a 2 0 0- mesh sieve. H . F . Ha r w o o d.
E x ten sio n of m e th o d s of g ra v im etric a n alysis.
L. Mo s e r (Monatsh., 1929, 53 and 54, 39—47).—A résumé of the following methods, which have been applied by the author and his co-workers to the determination of metals during the past 1 0 years.
(1) Temporary hydrolysis (cf. A., 1923, ii, 438), (2) repression of hydrolysis (A., 1922, ii, 315), (3) form
ation of sparingly soluble adsorption compounds with tannic acid, (4) formation of complexes with sulphosalicylic acid (A., 1925, ii, 329), and (5) thermal dissociation of ammonium halides (A., 1926, 814;
1927, 435). H. Bu r t o n.
D eterm in ation of d ilu te aqueous so lu tio n s of
“ arg y ro l ” b y p hotograp h ic nep helom etry.
F. Ri m a t t e i (J. Pharm. Chim., 1929, [viii], 10, 349—363).— An apparatus for the nephelometric determination by photographic means of very dilute colloidal solutions, e.g., “ argyrol,” is described.
Monochromatic light is used and. is usually produced by passing a beam from an electric arc through a green filter (Wratten 74 E), exposures being made on Lumière orthochromatic plates. The determin
ations may be made either by the nephelometry of absorption or of diffusion, the latter being the more sensitive ; both methods are considerably more accurate than visual nephelomotry. The differ
ence in the density of the deposit on the photo
graphic plate, produced by light passing through solutions of different titre, can be easily seen by the unassisted eye, whereas no difference can be detected in the solutions themselves. A “ metoquinone ” developer is used, the time of development varying from 10 to 15 min. The results obtained by tho more accurate nepholometric diffusion method agree with those obtained by weight to within 4%, using aqueous solutions of argyrol containing between 1 and 2 mg.
per litre. P. G. Ma r s h a l l.
M ea su rem en t of h yd rogen -ion con centration in unbuffered solu tio n s. I. A d sorb en t p ro p erties of p la tin ised p latin u m . I. M. Ko l t h o f f
and T. Ka m e d a (J. Amer. Chem. Soc., 1929, 51, 2888—2900).—The adsorption capabilities of platinised platinum in various salt solutions were investigated. In a hydrogen atmosphere the cation is adsorbed from a neutral salt solution and an equivalent amount of free acid is formed in the solution (cf. Frumkin and Donde, A., 1927, 1021).
Zinc sulphate solutions, in an atmosphere of hydrogen, increased in acidity to an extent equivalent to the amount of zinc adsorbed by the platinum. Ammon
ium chloride likewise became slightly acid, but in oxygen such solutions became very distinctly acid, and the acidity increased the longer the oxygen
was passed. This is attributed to the formation of hexa-aquoplatinic acid, which reacts with the ammonium ions present: H2Pt(OH)G-f2N H 4'— >- (NH4)2Pt(OH)„-f-2H\ Similar results were obtained with trimethylammonium and potassium chlorides.
No acid adsorption from hydrochloric acid occurs in a hydrogen atmosphere, but in an oxygen atmosphere there is equivalent adsorption of hydrogen and chlorine ions. Sodium hydroxido is strongly ad
sorbed in a hydrogen atmosphere; maximum adsorp
tion occurs at a concentration of 0-00072^. This adsorption is increased by addition of sodium chloride and in presence of large amounts of the latter the maximum disappears. In the presence of oxygen the hexa-aquoplatinic acid formed neutralises some of the alkali and only apparent adsorption of the latter, therefore, takes place. S. K. Tw e e d y.
A p p lication of d ifferen tial p o ten tiom etric titra tio n to th e d eterm in a tio n of w ea k acids in d ilu te solu tion . B. L. Cl a r k e and L. A. Wo o t e n
(J. Physical Chem., 1929, 33, 1468— 1480).—An apparatus and method for the differential potentio
metric titration of weak acids in concentrations of the order 0-0004iV are described. The theory of the method is developed and methods for determining the end-point are deduced. Data for 0 00042V-acetic acid titrated with O-OOliV-barium hydroxide are given. No indication of a second end-point in the presence of quinhydrone such as1 tliat observed by Maclnnes and Jones (A., 1927, 35) has been observed.
L. S. Th e o b a l d,
In dicators. XVI. S en sitiv ity and sta b ility of p h th a lein s and su lp h o n ep h th alein s to alkali.
A. Th i e l (Monatsh., 1929, 53 and 54, 1008— 1013).—
Comparison of a series of analogous phthaleins and sulphonephthaleins shows that the latter are the more stable at 18—20°; the velocity coefficients for decolorisation (cf. this vol., 445) are in the ratio of about 1000:1. In general, the sulpho-derivatives are also more sensitive; this is probably due to the existence of a secondary lactonic ion (cf. loc. cil.).
T h e absorption maxima (lower limiting curve) of the sulphonephthaleins ai-e about 5—-10 mji greater than for the analogous phthaleins. H. Bu r t o n.
D eterm in ation of h y d roxid e and carbonate in so lu tio n s. J. Li n d e r.—Sec B., 1929, 895.
D eterm in ation of ch lorin e and carbonyl chlorid e in m ix tu re s. S. Pl e t n e v (Lab. Praktika, 1928, 4, No. 2).—Tho free chlorine is determined in one sample with potassium iodide solution, and the total chlorine is determined in another sample which is collected in sodium hydroxide solution and treated with arsenious oxide and sodium carbonate.
Ch e m ic a l Ab s t r a c t s.
M icro-d eterm in atio n of iodin e in organic m aterial. J. F. Re i t h (Pharm. Weekblad, 1929,
6 6, 829—845; cf. this vol., 337).—The limits of sensitiveness in micro-determinations of free iodine in aqueous solutions are indicated for various conditions, and the effects of foreign ions are examined. The benzene method is not sufficiently sensitive for general use. Very good results are obtained by oxidation to iodate by means of bromine, and subsequent titration with thiosulphate of iodine liberated by the iodate;
GENERAL, PHYSICAL, AN D INORGANIC CHEMISTRY’. 1411 the presence of bromides interferes seriously. Nitrites
must first be destroyed by means of sodium azide.
The colorimetric determination of a chloroform extract is very suitable for small quantities, but laborious, and much affected by foreign ions. A colorimetric method based on oxidation to iodate, liberation of iodine by this, and addition of starch is also very accurate. For determination of iodine in potable and other waters, 0-5—3 litres after addition of about 2 c.c. pf saturated potassium hydroxide solution are evaporated to 50 c.c, filtered, and the solution evaporated to dryness with potassium nitrate.
The residue is ignited, taken up in water, and the filtration, evaporation, and ignition are repeated. The white residue is extracted with alcohol, the extract evaporated, and iodine determined in the residue by the bromine oxidation method. The necessary recautions are described in detail. Methods of etermination for soils are discussed. For urine, it is recommended to ignite the evaporation residue with a mixture of potassium nitrate and carbonate; nitrite is destroyed before the determination of iodine in the
final mass. S. I. Le v y.
S ta b ilised starch indicator. M. S . Ni c h o l s
(Ind. Eng. Chem. [Anal.], 1929, 1, 215).—50 G. of potato starch, mixed to a thin paste with 250 c.c. of cold water, are added gradually to 2 0 litres of boiling water, and the solution is boiled with continual stirring for a further 15 min. After partial cooling, 25 g. of salicylic acid are added, and dissolved by stirring. The reagent thus prepared keeps almost indefinitely, even although exposed to air, and is very sensitive. 2 C.c. are required for a 200 c.c. titration.
H. F. Ha r w o o d.
T itration of so lu b le iod id es in colloidal silv er iodide. R. B. Sm i t h and W. G. Ch r i s t i a n s e n.—
See B , 1929, 909.
R edu ction rea ction s w ith calcium hydride. I.
Rapid d eterm in ation of sulphur in in solu b le su lp h ates. W. F. Ca l d w e l l with F. C. Kr a u s- k o p f (J. Amer. Chem. S oc, 1929, 5 1 , 2936—2942).—
Heating with calcium carbide will not quantitatively reduce sulphates to sulphides. By observing certain precautions non-volatile sulphur compounds free from metals which form acid-insoluble sulphides may be quantitatively reduced to sulphides by fusion with calcium hydride; the sulphur may be determined in the fused mass by iodometric titration ; MS04+2CaH 2=
M S+2C aO +2H aO ; MSO,+4CaHa=M S+4CaO + 4H2; CaH2^ C a + 2 H ; M S+C a=C aS+M . With regard to the last two of these equations it was found that fusion of sodium thiosulphate with calcium hydride yields some metallic sodium.
S . K . Tw e e d y.
P oten tio m etric titra tio n of sulphuric acid.
S. Li n d a and J. Et t i n g e r (Rocz. Chem, 1929, 9, 504—522).—Sodium hydroxide solution and not acid should be used in the burette in the potentiometric titration of sulphuric acid, as the error due to carbon dioxide is thereby minimised, and the solution should be strongly agitated in order to reduce the time neces
sary for supervention of equilibrium. The disturbing influence of carbon dioxide is considerably less than in using caloriinetric methods of titration, and the
potentiometric method has the further advantage of permitting the accurate titration of 0-01A7-solutions.
Identical results are obtained using calomel or zero electrodes. It is of importance that the alkali solution be standardised under the same temperature conditions as are applied during titration.
R. Tr u s z k o w s k i.
N ew isom o rp h ou s ser ie s of flu orin e c o m pounds. H. Ca r o n and L. Va n b o c k s t a e l (J.
Pharm. Chim, 1929, [viii], 1 0 , 301—308).—A more detailed account of work already reviewed (this vol., 526). Micro-methods for the detection of small quantities of sulphuric acid in hydrofluoric acid and of sulphuric acid and aluminium in hydrofluosilicic acid are given. A. A. Go l d b e r g.
T u rb id im etric d eterm in ation of su lp h ate in ch rom iu m -p latin g b ath s. L. E. St o u t and A. W.
Pe t c h a f t.— S e e B , 1929, 901.
D eterm in ation of su lp h ate in ch ro m ic acid and in ch ro m iu m -p la tin g b ath s. H. H. Wi l l a r d and R. Sc h n e i d e w i n d.—See B , 1929, 895.
D eterm in atio n of s m a ll q u an tities of selen iu m in ores. E . T. Er i c k s o n.—See B , 1929, 899.
R apid d eterm in ation of n itrogen . F. M.
Wi e n i n g e r and M. Li n d e m a n n.—S e e B , 1929, 939.
M icro-d eterm in ation of n itra tes and n itrites.
K. Wo i d i c h (Oesterr. Chem.-Ztg, 1929, 3 2 , 1 8 3 ).— Devarda’s reduction method has been adapted for micro-chemical purposes, a determination requiring only 20 min. A special form of apparatus used for the reduction and distillation is described, the ammonia formed being collected in 0-0 2iV-sulphurie acid, and titrated with 0-02A7-sodium hydroxide. In the determination of nitrates and nitrites in water, the total ammonia formed by reduction is collected in water and determined eolorimetrically in the usual way, the nitrite being subsequently determined colorimetrically in a separate sample.
H . F. Ha r w o o d.
M olyb denu m -blu e m eth od for m ic r o -d e te r m in a tio n of p h osp h ate and arsen ate io n s. G.
De n i g e s.—See B , 1929, 939.
D eterm in ation of carbon d ioxid e in g a s e s con tain in g acetylene. H. Fr i e d r i c h.—See B , 1929, 877.
D eterm in atio n of alk a lis in m in era ls b y th e interferom eter. G. Bu r g e r (Monatsh, 1929, 5 3
and 5 4 , 985—988).—Using Lowe’s interferometer with distilled water as a comparison liquid the curve for the system 4% sodium chloride-4 % potassium chloride has been determined. The minerals studied (potash felspar, sanidine, natrolite, deep-sea earth, and kainite) are ignited with ammonium chloride and calcium carbonate, the calcium is removed as carbonate or oxalate, and the residue ignited re
peatedly with small amounts of hydrochloric acid (if sulphate is present this is removed as barium sulphate). The dry residue is dissolved in water to a 4% solution and its composition determined gravi- metrically and iriterferometrically. The two sets of values are in good agreement. H. Bu r t o n.
1412 B R IT ISH CHEMICAL ABSTRACTS.— A .
D eterm in ation of tru e so d iu m con tent of calciu m carbonate inten ded for u se in the L aw rence S m ith m eth od for a lk a lis. E. R.
Ca l e y (Ind. Eng. Chem. [Anal.], 1929, 1, 191— 192).
—-The usual method of weighing the residue obtained by extracting the calcium carbonate with water gives untrustworthy results. It is preferable to dissolve
2 g. of the material in hydrochloric acid, evaporate the solution to dryness, take up the residue with 2 to 3 c.c. of water, and determine the sodium directly by precipitation 'with magnesium uranyl acetate solution (this vol., 900). H . F. Ha r w o o d.
D eterm in ation of ca lciu m and m a g n e siu m in a lu m in iu m con tain in g other allo y in g elem en ts.
K. St e i n h ä u s e r.— S e e B., 1929, 899.
R apid d etection of th e m e ta ls of grou p I I : arsenic, an tim on y, tin, m ercu ry, b ism u th , lead, copper, and cad m iu m , by m e a n s of organ ic reagen ts. G. Se n s i and S . Se g h e z z o (Annali Chim. Appl., 1929, 19, 392—396).—For separating the sulphides of the metals of group II, a reagent prepared by adding 1 0 g. of sodium hydroxide to
1 0 0 c.c. of 2 0% sodium sulphide solution free from sulphates is recommended. The separate metals may then be detected by organic reagents.
T. H . Po p e.
U se of phenolic acid s in th e detection, sep ar
ation, and d eterm in ation of m eta ls. I. S ep ar
ation of 2A group (analytical) m e ta ls. P. N.
Da s-Gu p t a (J. Indian Chem. Soc., 1929, 6, 627—
633).—The action of tannic, gallic, and 2 : 4-dihydroxy- benzoic acids on the nitrates, chlorides, acetates, and sulphates of the metals of group 2A has been studied, and, as a result, alternative methods for the qualitative separation of the metals, using gallic acid when the metals are first precipitated as sulphides, and 2 :4-di- liydroxybenzoic acid when precipitation of sulphides is unnecessary, have been devised. These methods are based on the following experimental d a ta : (1) in dilute nitric acid solution gallic acid completely precipitates bismuth, whilst lead, copper, and cadmium are unaffected; (2) in neutral or faintly acid (nitric) solution gallio acid and sodium acetate precipitate lead and copper completely; (3) in neutral or dilute nitric acid solution hydrogen peroxide and ammonia precipitate lead completely, whilst copper remains in solution; (4) in dilute nitric acid solution of the metals 2 ; 4-dihydroxybenzoic acid precipitates completely mercury alone of all the group, the remaining metals then being separable by (1), (2), and (3).
M. S. Bu r r.
[U se of h exam eth ylen etetram in e in] m ic r o ch em ical an a ly sis. I. M. Ko r e n m a n (Pharm.
Zentr., 1929, 70, 709—714; cf. this vol., 286).—A
1 0% solution of hexamethylenetetramine yields crystalline precipitates with many phenols, such as resorcinol and pyrogallol; 0-0003 mg. of the latter may thus be detected under the microscope. A mixture of hexamethylenetetramine with an equi- molecular amount of ammonium thiocyanate, potassium bromide, or potassium iodide forms a more sensitive reagent for the micro-chemical detection of the heavy metals than hexamethylenetetramine alone, the iodide mixture giving the best results. This
reagent is especially sensitive for antimony and bis
muth, somewhat less so for mercury, lead, copper, cadmium, and tin. Oxidising agents must be absent, as these cause precipitation of periodides of hexa
methylenetetramine. H. F . Ha r w o o d.
D etection of h eavy m e ta ls b y m e a n s of " di- th izon e ” (diphenylthiocarbazone). H . Fi s c h e r
(Z. angew. Chem., 1929, 42, 1025—1027).—Dithizone forms coloured complex compounds with many metals, all of which, except manganese and the metals of the eighth group, belong to the sub-groups of the periodic classification. These compounds are charac
terised by insolubility in water and ammonia solution, and ready solubility in many organic solvents such as carbon tetrachloride and carbon disulphide (except in the case of the silver and gold compounds). Dithizone is soluble in carbon tetrachloride or disulphide to a bright green solution, and if a very dilute solution of the reagent be shaken with an almost neutral aqueous solution of one of the above metals a sharp change of colour in the non-aqueous layer results; 0 -0 0 1 mg.
of metal per c.c. of solution can thus be detected.
The metal may be identified by comparison of the colour produced with that of known standards.
Owing to the varying affinities of the metals for the reagent, it is possible to detect certain metals in the presence of others, e.g., silver in presence of all other
Owing to the varying affinities of the metals for the reagent, it is possible to detect certain metals in the presence of others, e.g., silver in presence of all other