The prep, and properties of various salts of the tetrazo-compounds of diaminodiphenyl and its

derivatives with naphtholdisulphonic acid are des­

cribed. They are unsuitable for photographic purposes. The diazo-compounds of diaminodiphenjd- amine, ammodiphenylamine, etc. are very sensitive to light. This fact is utilised in applying the theory of formation of azo-colours to photography.

J. W. S.

Photosynthesis in tropical sunlight. V. Re­

duction of carbonic acid, hydrogen carbonates, and carbonates. N. R. D h a r and A. R a m (Z. anorg.

Chem., 1932, 206, 171— 173; cf. A., 1931, 113S).- Mg, Zn, or FeC 03 will reduce C 02, C03", and HCOj to CH20 in the dark and, with Mg or Zn, to a greater extent in sunlight. ZnO is a photosensitiser. No

H C 02H is obtained. M. S. B.

Preparing cuprous chloride solution for gas analysis. R. E. S u m m e r s (Power, 1932, 75, 55).—

The ppt. obtained on passing SO, into CuSO4,5H20 (249-69 g.) and NaCl (87-69 g.) in H 20 (1000 c.c.) is washed quickly with saturated aq. S 0 2 and dis­

solved immediately in 6A-HC1 (500 c.c.).

Ch. Ab s.

Fluoroberyllates and their analogy with sul- ohates. III. Double sa lts. N . N . Ra y (Z. anorg.

Chem., 1932, 206, 209—216).—The analogy of fluoroberyllates with sulphates (cf. this vol., 131, 582) is shown by the formation of double

salts

^{^ of}

the general formula MI2BeE4,MIIBeE4,6H20 in which, when M1 is N H 4, Mn may be N i, Co, Mn, Zn, Cd, Cu, or Fe11; when M1 is K, M11 may be Ni or Co, and when M? is Rb IF 1 is Ni.

Sulphatoberyllales

have also been obtained in which more than half the BeF4" in the double salt is replaced by S04" : K 2N i(S 04,BeF4),6H20 and ( N H 4)2Z n ( S O 4, B e E 4) ,6 H 20 .

M. S. B.

[Preparation of] beryllium from the oxide.

G. D. F i t z p a t r i c k .—See B., 1932, 553.

Transform ation calcium sulphate hemi- hydrate— >-anhydrite in m o ist air at a t m o s p h e r i c

pressure. R. N a c k e n and K. F i l l (Tonind.-Ztg., 1931, 5 5,1194—1196; Chem. Zentr., 1931, ii, 3651)-—

The H ,0 is expelled from the stable hemihydrate at const, temp. Slow heating is necessary to obtain good heating curves of gypsum, which in a vac. at 20° changes to anhydrite. In dry air at 1 atm., it

G E N E R A L , P H Y S IC A L , A N D IN O R G A N IC C H E M IST R Y . 707

gives off its H 20 very slowly. Equilibrium curves for the system CaS04-H 20 have been obtained.

L. S. T.

Action of w ater ⁰¹¹ dicalcium phosphate. A.

S a n f o u r c h e and J. H e n r y (Compt. rend., 1932,194, 1940—1942).—The discrepancies reported as to the action of cold H 20 on CaH P04 (cf. A., 1900, ii, 618;

1907, ii, 261) are due to a false equilibrium analogous to supersaturation, decomp, in the cold occurring only in presence of Ca3(P 0 4)2, when CaH4(P 0 4)2 passes into solution, the max. decomp. (20% after 240 hr.) occur­

ring in a solution containing 1 g. of CaH P04,2H20 per litre. A t higher temp, and with more conc. solutions decomp, starts at once, the limit at 100°, attained in 1 hr., being 7-02% CaHP04 decomposed. At 75°

the undecomposed CaH P04 is present in both the hydrated (brushite) and anhyd. (monetite) forms, the former disappearing above this temp. C. A. S.

Form ation of sligh tly soluble calcium phos­

phate from aqueous solution and the relation of this phosphate to the apatite group. G. T r o m e l

and H. ^{M o l l e r ( Z .} anorg. Chem., 1932, 206, 227—

240).—By pptg. aq. Ca(N03)2 with aq. Na2H P 0 4 in presence of excess of aq. N H 3, hydroxyapatite, Ca10(PO4)0(OH)2, is first formed, and not Ca3(P 04)2.

The behaviour of the ppt. on drying depends on the opportunity to adsorb P20 6 and on the subsequent calcination at 950°, which causes the adsorbed P20 5 to react and become part of the crystal structure. It also prevents adsorption of excess of P 2Os. Usually a mixture of (3-Ca3(P 04)2 with hydroxyapatite is obtained. The transformation to Ca3(P 04)2 may also take place by long heating at a lower temp.,

e.g., 600°. M. S. B.

Hydrothermal synthesis of calcium silicates.

S. N a g a i (Z. anorg. Chem., 1932, 206, 177—195).—A collection and discussion of the data, previously obtained by the author, relating to the thermal synthesis of Ca silicates, with and without H20 vapour, under pressure, and at atm. pressure (cf. A., 1931, 1020,1380; this vol. 131,350; B., 1932, 25, 262).

M. S. B.

H ydrotherm al sy n th esis of ca lciu m alum inates and silic a tes fr o m lim e and a lu m in a or kaolin.

I- S . Na g a i(J. So c. Chem. Ind. Japan, 1932,3 5 ,182— 184b).—The combined H 20 is removed from kaolin by beating at 500—600°; only part of the A120 3 content is sol. in 5% HC1 after the material has been heated at 900°. Al(OH)3 loses H20 at 400—500°, and the residue is easily sol. in 5% HC1 if it is not heated above S00°. The composition of a wet mixture of CaO and Al(OH)3 (1 : 2) after heating under normal pressure at temp, between 800° and 1100° is practically the same as that of a dry mixture heated at the same temp. At 10—20 atm., however, wet mixtures of CaO with Al(OH)3, A120 3, or kaolin readily yield Ca aluminates and/or silicates. H. E. G.

Preparation, vap o u r p r e ssu r e s, and d en sities of boron triflu orid e, a rsen ic pentafluoride, and bromine triflu orid e. O . R u f f [with A. B r a i d a ,

0- B r e t s c h n e i d e r , W. M e n z e l , and H. P l a u t ] (Z.

anorg. Chem., 1932, 206, 59—64).—SiE4, which is anvays present in BF3 made in the usual way, cannot be separated by fractional distillation, but may be

greatly reduced in quantity by passage over B ,0 2 at 800°. BE3 containing <1-7% SiF4 had m. p.

-1 2 8 ° , b. p. —101°/760 mm., d (liquid) 2-6999—

0-00642(273-H), d (solid) 1-87 (min. val.). AsF6 was made by direct combination of the elem ents;

m. p. —79-8°, b. p. —52-8°, v.d. 169-5, d (liquid) 3-505—0-00534(273+0, «H1 (solid) 3-02 (min. val.).

BrF3, from Br and F2, had m. p. 8-8°, <1 (liquid) 3-623—0 - 0 0 2 7 7 ( 2 7 3 + * ) , (solid) 3-23 (min. val.).

V. p. of BF3 and AsF5 are given, and the chemical behaviour of AsF5 is described. F. L. U.

Selenates of lanthanum and their solubilities in water. J. A. N. F r i e n d (J.C.S., 1932, 1597—

1602).—Anhyd. La2(Se04)3 and its 5-, 6-, 12-, and 22(?)-hydrates have been prepared and analysed, and solubilities of the last two determined between 0° and 95°. The solubility curves closely resemble those of the 12- and 22-hydrates of Nd2(Se04)3. F. L. U.

M esothorium. II. G . G u e b e n (Ann. Soc. Sci.

Bruxelles, 1932, [ii], 52, 60—66).—-Ms ¹¹ has been separated from accompanying radioactive elements and its a-radiation measured. E. S. H.

Carbon m onoxide from carbonates. S. T.

B o w d e n and T. ^{J o h n} (Nature, 1932, 129, 833).—Na reacts smoothly with a warm xylene solution of Ph2C03 forming NaOPh and pure CO. The CO is dry enough not to explode with dried 0 2. Alkyl carbonates react in a similar manner. The reaction occurs through the intermediate formation of ketylic

derivatives. L. S. T.

Decom position of lead nitrate in molten potassium nitrate. K. L a y b o u r n and W. M . M a d g i n (J.C.S., 1932, 1360—1364; cf. this vol., 468).

—The primary product of decomp, of Pb(N 03)2 in molten K N 0 3 at 357° is Pb 0,2P b (N 03)2, which is subsequently oxidised to Pb30 4,3Pb(N03)2. Each of these products is hydrolysed by boiling H20 to form P b (0II)N 03, whilst the second gives a residue of P b 02 both when hydrolysed and when treated with dil.

acids. F. L. U.

“ Mineral caoutchouc ^" [phosphonitrilic chlor­

ides]. P. R e n a t j d (Compt. rend., 1932,194, 2054—

2056).—The caoutchouc-like products obtained by heating carefully dried trimeric phosphonitrilic chloride, P3N3C10 (cf. A., 1924, ii, 752), have been examined. When strongly cooled they become hard and progressively more cryst., returning to the amorphous, soft, gummy condition on warming;

the changes were confirmed by X-ray examination.

The products swell in C6H 6, and partly dissolve, the solution depositing crystals. By heating in vac. at 500°, lighter polymerides, cryst. or liquid, are produced.

Mols. of P3N3Clfi probably unite, forming chains includ­

ing cells, the connexion between which is loosened by heat (cf. A., 1923, ii, 134). C. A. S.

Dehydration of niobic acid. P. ^{S u e} (Compt.

rend., 1932, 194, 1745—1747).— On drying in vac.

over solid KOH niobic acid obtained by the pptn. of an alkaline solution of a niobate by aq. HC1 there are doubtful indications of possible hydrates Nb20 5,3H20 and Nb20 s,4H20 , but these lose H ,0 over H 2S 0 4 or P20 5. Dehydration at 100° for 4 months, at 195—260° and 400—540°, affords products corre­

7 0 8 B R IT IS H C H E M IC A L A B S T R A C T S .— -A .

sponding with hydrates containing approx. 1, 0-66, and 0-33H2O, respectively (cf. A., 1930, 1538).

C. A. S.

F orm a tion of ozone at high, tem p era tu res. P.

H a r t e c k (Z. physikal. Ghem., 1932, B , 17, 120—

126).—Tho amount of 0 3 present in ah or 0 2 which has been passed over a heated Nornst pencil and then chilled rapidly (A., 1907, ii, 163, 340) is far greater than corresponds with the equilibrium 3 0 2w=^203 at the high temp. (cf. A., 1911, ii, 1). The 0 3 is probably formed by the reaction 0 + 0 2= 0 3 during

the cooling. R. C.

C hanges of th e s a lts of tervalen t m e ta ls in solu tio n . C. M o n t e m a r t i n i and E. V e r n a z z a (Ind.

chim., 1931, 6, 1124— 1128; Chem. Zentr., 1931, ii, 3588—3599; cf. this vol., 351).—Tho change produced by heating and quickly cooling Cr alum solutions prepared from green solutions has been investigated.

Two diSerent forms of green Cr2(S04)3 exist. K and N H , Fe alums show no corresponding difference in the C02 evolved with Zn oxycarbonate when solutions

arc heated and cooled. L. S. T.

C on stitu tion of b lu e p erch rom ic acid. R.

Schw arz and H. G iese (Ber., 1932, 65, [J3], 871—

876).—Determinations of the mol. wt. of “ pyridine perchromate ” in freezing C6H 6, P h N 0 2, CHBrs, or pyridine confirm tho unimol. structure. Tho pos­

sibility that perchromic acid is H 2Cr05 is excluded, since it combines with only 1 mol. of org. bases,

e .g ., N H 2Ph, pyridine, or quinoline, is decomposed

by Ag20 with formation of Ag2Cr04 and O, and immediately evolves O, when brought into contact with alkali hydroxide. Its acidic character is there­

fore denied and it is considered to be a peroxide 0!C r^<^ V . In support of this view the following evidence is adduced. Decomp, of the pyridine salt (actually a mol. compound [C6H 5N ,C r05]) with dil.

H2S 0 4 yields a Cr*'* salt and 0 , 2Cr06=C r20 3-)-70.

Decomp, of the peroxide in E t20 by Ag20 occurs thus : Cr05= C r 0 3+ 2 0 . Titration with KM n04 in neutral solution gives chromate and consumes 4 equivs. of O, showing thus 2-0-0- groups; Cr06-|- 2H20 == Cr 0 3+ 2H20 2 and 2H20 2+ 2 0 = 2 H 20 + 2 0 2.

The stability of the compound hi E t20 is ascribed to the production of an etherate. Tho metal is sexavalent in the peroxide. H. W.

M olyb denu m sesq u isu lp h id e. G u iciiard (Bull.

Soc. chim., 1932, [iv], 51, 563—564).—Failures to prepare Mo2S3 (cf., in t e r a l i a , Picon, A., 1929, 1012) result from heating MoS2 in a vac., whereas, as originally stated (A., 1901, ii, 659), it is obtained only when MoS2 is heated under ordinary pressure.

B oro-m o ly b d ic b lu e. P. ^Ck i s t o l and J. ^{Ca y l a} (Compt. rend., 1932-, 194, 1942— 1944).—On adding Deniges’ sulphomolybdic reagent (cf. A., 1920, ii, 770) and SnCl2 to aq. Na borate in the cold a blue coloration is formed. If hot, Cu or A1 may replace SnCl2. A mixture of Na borate, a mineral acid, an alkali molybdate, and E taO exposed to sunlight turns blue. From the aq. solution acidified with H 2S 0 4, Et-20 extracts the blue compound, and H 20 removes it from E t20 solution. When purified by repeated

alternate extractions from H 20 and E t20 it contains B, and is very readily oxidised to a yellow solution, whilst when further reduced it becomes violet-rose.

On keeping rhombohedral crystals are deposited.

It is stable in presence of Na borate. Si, V, and other elements produce similar compounds.

C. A. S.

Quantitative separation of tungsten mono­

carbide from hem icarbide and tungsten, and conditions of form ation of the carbides. I.

I ita k a and Y. A oki (Bull. Chem. Soc. Japan, 1932, 6, 10S— 114).—When W and C are heated together the proportion of WC formed increases from 3% at 1600° to 42% at 2500°, and the product always contains W2C (40—S0%). The presence of Fe is not necessary. WC is not noticeably decomposed into W2C and C even on slow cooling. A method of separation of WC from reaction products is based on the fact that it does not react with Cl2 below 600°, whereas both W and W2C are converted into volatile

chlorides below 550°. F. L. U.

Compounds of quadrivalent uranium [and thorium ]. A. Rosenheim and RI. K e lh y (Z. anorg.

Chem., 1932, 206, 31—43).—Tho following

compounds

are described: UCl4,10H„O; (C5H GN)„UC16,2H,0;

UiOHWHCOaio^IRO ; U(OAc)4;

“ " K4H 2[U0(o-CfiH40 2)7],3H20 ; (CHcN 3)e[U2(o-CfiH40 2)7],14H20 ; (C6H 0N)[U(o-CbH4O2)2OH],4H2O ; (C2H 5N4)[U(o-CfiH4O,)2OH],20tt,O ;

(CH6N 3)6[Ü(C03)5],4H20 ; (CHgN3)5[U(C03)3(0H )3],5H20 ;

(CHGN 3)5[Th(C03)3(0H )3],5H20 ; (NH4)4[U (S03)4] ; N aR[U2(SO3)7],20H2O ; K 0[U2(SO3)7],12H2O ; ( C H ^ U i S O ^ O H J ^ O ;

(NH4)4[Th(S03)4],6H20 ; Na4[U(P20 7),],8H20.

F. L. U.

E sters of fluorosulphonic acid. J. M eyer and G. Scheamm (Z. anorg. Chem., 1932, 203, 24—30).—

A nearly quant, yield of F S 0 3H is obtained by distilling a mixture of oleum with K IIF2. The dry acid, b. p. 110o/120 mm., 77°/19 mm. d \3 1-740, does not attack glass. Many reactions are described.

Me20 and E t20 give the corresponding esters as colourless liquids immiscible with, but readily hydrolysed by, H 20 . F S 0 2‘OMo has b. p. 92°, 45o/160 mm., d)6 1-427. FSOa-OEt has b. p. 1137752 mm., 240/12 mm., d 1-310. F. L. U.

Rhenium trioxide. W. B ilt z and G. A. Leheer [with K. M e ise l] (Nachr. Ges. Wiss. Gottingen, 1931, 191— 198; Chem. Zentr., 1932, i, 1070).- R e 0 3 was prepared by reduction of Re20 7 (by oxid­

ation of Re in 0 2 at 360—400°) with finely-divided Re (by reduction of NH 4R e04) in a sealed tube at 200—250° followed by oxidation with Re20 7 at 250°.

The m. p. (vac.) of Re20 7 is 301-5°; sublimation begins at 220°. R e 0 3 is attacked by H N 03, hut not by hot HC1. Disproportionation occurs on thermal decomp, or by dissolution in NaOH. The unit cube has

a

3-73

Â.

; dob,. 6-9, d«lc. 7-4. A. A. E.

Rhenium oxychlorides. A. B r u k l and K- Z ie g le r (Bor., 1932, 65, [ B ] , 9 1 6—9 1 8).—The interaction of ReCl4 and Re20 7 affords oxychlorides separable from one another with great difficulty.

G E N E R A L , P H Y S I C A L , A N D IN O R G A N IC C H E M IS T R Y . 7 0 9

Re trioxychloride, R e 0³Cl, m. p. -f-4-53, b. p. 131°

(corr.), is prepared by passing 0 2 through a tube containing Re in two boats placed so that one can be heated without affecting the other. The front boat is gently warmed, whereby the metal is converted into Re20 7. 02 is replaced by Cl, and the rear boat is heated, thus giving ReCl4, which reacts with Re²0⁷ giving a mixture of oxychlorides condensed at —65°

and fractionated. I t is readily hydrolysed to per- rhenic acid and HC1. R e oxytetrachloride, ReOCl4, m. p. 29-3°, b. p. 223°, is obtained by the action of 0 , on ReCL. When heated in 0 , it passes into

Re0³Cl. " H. W.

Ferryl ion, a compound of quadrivalent iron.

W. C. B r a y and M. H. G o r i n '(J. Amer. Chem. Soc., 1932, 5 4 , 2124—2125).—The results of kinetic* in­

vestigations point to the formation of FeO" as an intermediate compound, and agree with the theory that 2Fe"‘+ I I20=Fe"'-(-Fe0**-}-2H' is a reversible and fairly rapid reaction. C. J. W. (c)

y-Ferric oxide hydrate. 0 . B a u d i s c h and W. H. A l b r e c h t (J. Amer. Chem. Soc., 1932, 5 4 ,

943—947).—The y-hydrate (A., 1929, 869), as well as the a-hydrate, is formed by autoxidation of aq.

Fe(HC03)2. The 0-complex theory (A., 1924, i, 1141; 1928, 856) is supported by the formation of the y-hydrate by atm. oxidation of aq. FeCl2 and in presence of certain org. N compounds. Magnetic data for the y-hydrate are given. W. C. F. (c)

P reparation of h exam m in etrio ld ico b a ltic ch lor­

ide and of n u clear p o ly m erid es. T. D a s - G u p t a

and P. B. S a r k a r (J. Indian Chem. Soc., 1932, 9, 79—82).—B y treating dichloroaquotriamminecobaltic chloride with hexamethylenetetramine instead of with NaOH, the yield of hexamminetrioldicobaltic chloride (=[A]C13) is increased from 12-5 to 62-5%. Treat­

ment of the latter substance with Na²S²0³ gives the

th io su lp h a le, [A]2(S203)3,4H20 , a red powder insol. in H20. D o d e c a m m in e h e x o lte tr a c o b a ltic th io s u lp h a le ,

[Coln{(On)2Co(NH3).)}3](S20 3)3,4H20, a co-ordination isomeride of the former product, is obtained as black crystals on treating the corresponding nitrate with

Na²S²0 3. F. L. U.

Double and co m p lex sa lts and circular di- chroism. J. P. M a t h i e t j (Compt. rend., 1932,1 9 4 ,

1727—1729).—If excess of aq. Na² tartrate is added to a Co" solution rosettes of pale rose needles are formed of (dried at 120°) Na²Co(C⁴H.OG)2, behaving as an ordinary double salt. If to a mixture of equal vols. of 2 M -Co( N 0 3)2 and 2ff/-Na²C⁴H⁴O^{0 4}M-NaOH is added until the ppt. first formed is redissolved, and then slowly, with agitation, more aq. NaOH, a red transparent jelly form s; when kept in a closed vessel this changes to a very easily oxidised solution, and deposits rose-coloured microscopic crystals of (dried at 120°) Na2CoC4H4Ofi. This behaves as a complex salt, probably' Na2[CoC4H40 G],«H20 . Al­

though solutions of both salts show similar absorption hands, their optical activities are different, and only the latter exhibits circular dichrosim. C. A. S.

Application of crysta llog ra p h ic m easu rem en ts to the identification and d eterm in ation of ch em i­

cal products. P. T e r p s t r a (Natuurwetensch. Tijds..

1932, 14, 168—170). H. F. G.

Neutral, buffered standard for hydrogen-ion work and accurate titrations, w hich can be pre­

pared in one m inute. R. J. W i l l i a m s and C . M.

L y m a n (J. Amer. Chem. Soc., 1932, 54, 1911— 1912).

—The p a of NH⁴0Ac solution over a wide range of concn. is almost exactly 7. W. T. H. (c)

G lass electrode in titrim etric w ork and pre­

cipitation reactions. Application of the prin­

ciple of solubility product to basic precipitates.

H. T. S. B r i t t o n and R. A. R o b i n s o n (Trans. Fara­

day Soc., 1932, 28, 531— 545).—For accurate work, frequent calibration of the glass electrode is necessary', especially in strongly' alkaline solution, and this is effected conveniently by' means of the titration of a universal buffer solution (A., 1931, 910). The elec­

trode affords accurate p n vals. between ² and ^{1 2} in buffered solutions, and errors accompanying the titration of unbuffered solutions are confined to narrow regions in which large variations of p a val. occur. In general, the results are not affected by ppts. The p a

curves (determined by glass electrode) for the titration of Zn salts with NaOH do not agree with those of others (A., 1931, 565, 1260; cf. A., 1925, ii, 1203).

Reasons for the discrepancy are discussed. Whilst the solubility product principle applies to p a data for the pptn. of AgOH, the use of the p K val. at a single point in the formation of a basic ppt. does not, in general, lead to an accurate knowledge of the true

solubility product. J. G. A. G.

Determ ination of active hydrogen in sm all quantities of substances by the m ethod of Tschugaev and Zerevitinov. II. R o t h (Mikro- chem., 1932, 11, 140— 156).—Errors in the micro- determination of CH4 produced in a reaction MeMgl-f- RO H =CH 4+ROM gI due to the presence of air or moisture can in practice bo eliminated by careful drying of the apparatus and by working in an atm. of dry' N2. A further error, arising from the production of C²IIc when the temp, exceeds 50°, has been traced to the presence of Mel as an impurity, and may be avoided by using MeOPh instead of (C⁵H u )20 as a solvent. Details of tests are given. F. L. U.

Determ ination of ozone in ozonised air. E. H.

R i e s e n f e l d ; P. K r a i s and H. M a r k e r t .—See B., 1932, 546.

Determ ination of w ater by distillation w ith liquids lighter than water. H. L u n d i n and M.

L u n d i n .—See B., 1932, 531.

Alkalim etric m icro-determ ination of chlorine and brom ine in organic substances. M. K.

Z a c h e r l and H. G. K r a x n i c k (Mikrochem., 1932, 11, Gl—^{7 3}),—^{4— 6} mg. of the substance are mixed with K2Cr207 and Ag2Cr207 and the mixture is heated with cone. H^S0⁴ at 115— 125°, whilst a stream of 0² carries the liberated Cl2 or Br into an absorption vessel con­

taining a measured quantity of O-OlA-NaOH to which H„02 has been added. The alkali used (Cl2-f-2NaOH - r lL0 2= 2NaCl-f 02-fH20) is then determined by titration. The method is rapid and accurate, but cannot be used for very' volatile substances.

F. L. U.

710 B R I T I S H C H E M IC A L A B S T R A C T S .— A .

Quantitative re-form ation of iodine by acidi­

fying an alkaline iodin e-potassium iodide solu­

tion. M. K o h n e (Z. anal. Chem., 1932, 88, 161—

170).—The I in an I-K I solution, which has been transformed into a mixture of I 0 3' and I' by the addition of alkali, is not quantitatively re-formed by acidifying. In a 0-1 xV solution the loss is 0-3—0-5%, in agreement with the results of King and Jette (A., 1930, 441). The error is not sufficient to render the iodometric method useless for the determination of S20 8". The abnormally large errors observed by other investigators are probably due to impurities in the KI. In 0-01N solution the error is very much larger than in 0-liV-I and varies with alkali of different origin, even when analytically pure. The error is not proportional to the amount of OH' and is probably not due to impurities, but is the result of a slight decomp., with evolution of 0 2, of the KIO formed intermediately, or of a slight volatility of free I in alkaline solution. The error is increased by the presence of large quantities of neutral salt.

M. S. B.

Iodom etric determ ination of total sulphur in polysulphides. P. S z e b e r e n y i (Z. anal. Chem.,

1932, 88, 187— 189).—The method depends on the fact that, by direct titration of Na^S* with I, N al and S are formed, but if the solution is made alkaline with NaOH and heated with excess of I solution S is oxidised to S 0 4" and, by acidifying, the unused I is set free from the NalO and N a l formed in the reaction and can be titrated. A correction must be made for Na.2S20 3 which is always present and is also oxidised to S 0 4". The amount of Na2S20 3 present can be deter­

mined by the titration to Na2S40 G after treating with excess of Zn or Cd acetate and filtering to remove sulphide. The amount of I used by the oxidation of Na2S20 3 to Na2S 0 4 is 8 tunes that required for oxid­

ation to Na2S40 G, so this quantity must be subtracted from the total I required for the complete oxidation.

The result may be controlled by titration of the II2S 0 4

formed. M. S. B.

A n a l y s i s o f h y d r o g e n s u l p h i t e s . A. P o n t e

(Boll. Uff. Staz. sperim. Ind. Pelli, 1932, 10, 155—

161).—When a solution containing both H sulphite and sulphite is titrated (phenolphthalein), 1 c.c. of Ar-NaOH“ 0-064 g. of S 0 2 semi-combined as HSOs and not, as stated in various text-books, 0-032 g.

T. H. P.

A nalysis of hyposulphite by m eans of azo-dyes.

V. I. M i n a e v , S. S. F r o l o v , and G. M. M a i o r o v . —

See B., 1932, 545.

V olum etric determ ination of persulphate ion.

A . K u r t e n a c k e r (Z. anal. Chem., 1932, 88, 171—

172).—The error previously observed in the iodo­

metric determination of S20 8" (A., 1931, 451) was apparently due to the presence, even in the purest commercial K I, of a small quantity of org. impurity with a strong reducing action in alkaline solution.

When this is absent the method gives very accurate

results. M. S. B.

Volum etric determ ination of persulphate.

J. H. v a n d e r M e u l e n (Z. anal. Chem., 1932, 88, 173— 179).—The iodometric determination of S20 8"

is not influenced by an excess of pure KI. A 20— 40%

excess of NaOH or KOH over that theoretically re­

quired is desirable, but a larger excess has no influence.

The presence of a few drops of aq. 0 s 0 4 catalyses the I 0 3' formation and helps to check the action of any reducing agent present. Boiling the liquid is not necessary. It should be gently warmed on the

The presence of a few drops of aq. 0 s 0 4 catalyses the I 0 3' formation and helps to check the action of any reducing agent present. Boiling the liquid is not necessary. It should be gently warmed on the

W dokumencie British Chemical Abstracts. A. Pure Chemistry, July (Stron 40-50)