tween 0-052V and O'0025AT enabled satisfactory titrations to be made. H. T. S. B r i t t o n .
Com parative colorim etric investigations. R.
Wasm uht (Z. angew. Chem., 1929, 42, 133—134).—
Determination of iron as ferrocyanide with a dipping colorimeter gave results in good agreement with the titration method of Zimmermann and R einhardt. For the colorimetric determination of manganese using potassium permanganate as standard, lead peroxide is more satisfactory as the oxidising agent than ammonium persulphate, since the colour given by the latter inclines to a rose shade and can be matched with the purplish tin t of the permanganate only by the use of a compensating colorimeter.
F . R. En n o s. V olum etric determ ination of sodium and p otassiu m ferrocyanides, u sin g zinc sulphate solution. A z o t C h e m ic a l F a c t o r y , J a w o r z n o (Przemysł Chem., 1929, 13 , 65—66).—Ferrocyanide solutions are titrated with 0-2iV-zinc sulphate solution, the end-point being ascertained by observing when drops of the solution fail to give a blue coloration on ash-free filter-paper wetted with ferrous ammonium sulphate. The equivalent value of the zinc sulphate solution has previously to bo determined separately for sodium and for potassium ferrocyanides.
R. Tru sz k o w sk i. D iphenylam ine as oxidation-reduction indi
cator for indirect titration of cobalt. J . G i l l i s and V. C u v e l i e r (Natuurwetensch. Tijds., 1929,11, 20—24).—The method of Willard and H all (A., 1922, ii, 875) has been modified, after examination by potentiometric methods, to perm it of the use of diphenylamine as internal indicator. The alkaline solution, after oxidation by means of sodium per
borate, and removal of the excess by boiling, is re
duced by a known excess of stannous chloride, and this excess, together with the ferrous salt formed from any iron present, is determined by means of potassium dichromate in presence of the indicator.
The parallel potentiometric titrations show th a t the minimum quantity of indicator m ust be used, and m ust be added only towards the end of the titration, and a small correction m ust be made. W ith these precautions, accurate results are obtained in the presence of nickel, and of considerable proportions of
iron. y. I . Le v y.
Volum etric determ ination of cobalt. G. A.
Ba r b ie r i (Atti R. Accad. Lincei, 1928, [vi], 8, 405—
408).—In the green liquids which result from the decomposition of cobaltinitrites by means of hot sodium hydrogen carbonate. (A., 1928, 973), all the nitro-groups of the original cobaltinitroso-complex are present as alkali nitrite, whilst the tervalent cobalt exists as cobalticarbonate, to which the green colour is due. When the green liquid is added to permanganate solution acidified with sulphuric acid, the nitrous acid is oxidised quantitatively in the cold to nitric acid and the tervalent cobalt is reduced to the bivalent form, eleven equivalents of the per
m anganate oxygen being consumed for each molecule of the cobaltinitrite. This reaction forms the basis
GENERAL, PH YSICA L, AND INORGANIC CHEMISTRY. 417 of volumetric determinations of potassium (Ind.
saccarifera ital., 1928, 21, 387) and of cobalt, the details of the procedure in th e latter case being now
described. T. H . Po p e.
Reactions of m olybdates, nitrophosphom olyb- dates, tungstates, and phosphotungstates. T.
Gaspary Ar n a l (A nal. Fis. Quim., 1928, 26, 435—
445).—The precipitation reactions are given in tabular form of solutions of sodium molybdate, ammonium molybdate, sodium nitrophosphomolybd- ate, sodium tungstate, and sodium phosphotungstatc with lithium, sodium, ammonium, potassium, cupric, rubidium, silver, cæsium, beryllium, magnesium, calcium, zinc, strontium , cadmium, barium, mercurous, mercuric, aluminium, thallium, lead, thorium, bis
muth, uranyl, manganous, ferric, nickel, and cobalt salts in aqueous solution and, in some cases, in aqueous-alcoholic solution. The results are discussed, particularly from the point of view of the possibility of separation of metals by the use of these reagents.
JR. K . C a llo w . Gravim etric m icro-determ ination of m olyb
denum. J . B. N i e d e r l and (Miss) E. P. S i l b e r t (J. Amer. Chem. Soc., 1929, 5 1 , 376—377).—Pregl’s method for the micro-determination of metals in organic substances m ay be used in principle for the gravimetric micro-determination of molybdenum as trioxide in substances containing no other non
combustible or non-volatile constituents.
S. K . Tw e e d y. Potentiom etric determ ination of titanium in the presence of other m etals, especially iron.
H. B r i n t z i n g e r and W. S c h i e f e r d e c k e r (Z. anal.
Chem., 1929, 7 6 , 277—280).—The solution is treated with 20 g. of calcium chloride crystals (or 12 g. of sodium chloride) and 10—20 c.c. of concentrated hydrochloric acid, diluted to 100 c.c., and titrated in an atmosphere of carbon dioxide a t 90° with chromous chloride. Ferric chloride is reduced first, then cupric to cuprous chloride, and finally titanic to titanous chloride, the end-point being marked in all cases by an appreciable potential fall.
A. R. Po w e l l. Determ ination of traces of antim ony in copper and its alloys. S. G. C l a r k e and B. S. E v a n s .—
See B., 1929, 175.
Solubility of Reinsch. antim ony film s in water.
S. G. Cl a r k e (Analyst, 1929, 54, 99—101).—If washing of the film with water is unduly prolonged appreciable amounts of antimony are removed, the solubility being due to the presence of dissolved oxygen. Ordinary distilled water m ay safely be used provided the washing occupies a few seconds only.
J . S. Ca r t e r. Determ ination of the platinum m etals in ores and concentrates. H. R. A d am .—See B., 1929, 212.
Methods and apparatus used in the cryogenic laboratory. XX. H igh-vacuum pum p. W.
G a e d e and W. H. K e e so m (Proc. K. Akad. W etensch.
Amsterdam, 1928, 3 1 , 985—988).—Details are given of a mercury diffusion pump with an exhausting capacity a t 0-15 mm. pressure of 130 litres/see. for air, and 42Ô litres/sec. for helium. F. G. T r y h o r n .
Gas density balance. A. S t o c k (Z. physikal.
Chem., 1928, 1 3 9 , 47—52).—An improved form of density balance is described in which the beam con
taining a small piece of soft non is controlled by means of an external electromagnet. An ammeter m ay then be conveniently calibrated to read gas densities.
R. W. Lu n t. Determ ination of refractive indices of m aterials, especially of fused m ixtu res, used in the Becke im m ersion m ethod. A. G o o s s e n s (Natuurwetensch. Tijds., 1929, 1 1 , 1—5).—The method of the Duke of Chaulnes, in which the ap
parent depth of a layer of liquid of known refractive index, and th a t of a layer of the liquid to be examined, of the same thickness, are determined by means of a vertically moving microscope, is modified for measure
ments with transparent solids. S. I. L e v y . Extraction apparatus. S. J . G a s p e r I k (Chem.
Listy, 1929, 2 3 , 58—59).—A modification of Soxhlet’s extraction apparatus is described.
R . Tr u sz k o w sk i. Continuous laboratory extractor for liquids.
A. W. F r a n c i s (Ind. Eng. Chem. [Anal.], 1929, 1, 15).—The sample is drawn into a pipette bulb packed with glass beads and the condensed vapour of the extracting liquid allowed to bubble up or down according as it is lighter or heavier th an the sample.
C. Ir w in. E xtraction apparatus for liquids. II. J.
Fr ie d r ic h s (Chem . F a b r., 1929, 90—91; cf. A., 1928, 389).—T h e co m p a ra tiv e ra te s of e x tra c tio n of O-OliV-aqueous benzoic acid b y chloroform , carb o n disulphide, a n d carb o n te tra c h lo rid e in v ario u s ty p es of e x tra c to r w ere d eterm in ed . A glass sp ira l to p re v e n t th e e x tra c tin g liq u id ta k in g th e s h o rte s t p a th , or a condenser w ith se rra te d edges, w as less efficient th a n a d is trib u to r consisting of fine hollow p o in ts dipping in to th e solution, a n d th is in t u r n less th a n th e porous glass frits designed b y th e a u th o r.
C. Ir w in. M icro-extraction m e th o d . J . B. N i e d e r l (J.
Amer. Chem. Soc., 1929, 51 , 474—475).—One drop of the liquid and one drop of extraction medium are repeatedly centrifuged in a sealed capillary tube so th a t the layer of higher density is forced through the layer of lower density. The tube is then separated under a microscope a t the boundary of the two
liquids. S. K. T w e e d y .
H aughton-H anson therm ostat. M ethod of fine adjustm ent. P. J . D u r r a n t (Inst. Metals, March, 1929, advance copy, 4 pp.).—In a method by which the tem perature of the Haughton-Hanson therm ostat can be adjusted to within 04° over a range of 5°, the “ cold bulb ” is placed in a small toluene therm ostat, and the tem perature of this is controlled by a movable w ire'in a mercury U-tube.
The tem perature of the therm ostat depends on th a t of the “ cold bulb,” winch in t o n depends on the level of the wire. Preliminary experiments enable a scale to be drawn by the side of the wire.
W . H u m e - R o th e r y . Apparatus for vapour - pressure determ in
ations. O. A. P i c k e t t (Ind. Eng. Chem. [Anal.], 1929, 1, 36—38).—Ramsay and Young’s
vapour-418 B R IT ISH CHEMICAL ABSTRACTS.:— A.
pressure apparatus is modified by th e insertion of a reflux condenser after the boiling tube. A mercury thermometer is used for approximate readings and a platinum resistance thermometer for precision, each being fitted with a cotton wick. By the use of differ
ent bath-liquids data over the tem perature range 10—220° can be obtained in 2—4 hrs. with an accuracy
of 0'5% . C. Ir w in.
P ressu re regulator for vacuum distillations.
H. L. Cox (Ind. Eng. Chem. [Anal.], 1929,1, 7—8).—
A closed-arm mercury manometer contains an adjust
able contact in the open side and a fixed contact in the top of the same side. These are connccted in series to a battery and a relay operating the motor vacuum pump. Any desired pressure between 2 mm. and atmosphere can be maintained to within 0-1 mm.
C. Ir w in. S ublim ation m ercury still. K. H ic k m a n (J.
Opt. Soc. Amer., 1929, 18, 62—68).—An improved type of electrically heated glass still is described. A number of units can be worked in series, condensed mercury which ordinarily falls back into the m other- liquor being passed on to the next still. The still works automatically, and an advantage claimed is th a t the need for frequent chemical treatm ent of them crcury before distillation is avoided. N. M. B lig ii.
A utom atic m ercury still. F. L. K o b e s o n (J.
Opt. Soc. Amer., 1929, 18, 72—74).—An easily con
structed glass still is described employing two baro
metric columns to maintain the vacuum. The still starts and stops automatically, and needs little attention. The power required is 90 w atts for an output of 100 g./hr. of mercury. N. M. B ligii:.
S till for liquids of high b. p. K. H ic k m a n (J.
Opt. Soc. Amer., 1929, 18, 69—71).—The apparatus is in the form of an alembic, and works on the principle th a t distillation can take place rapidly under very low pressures if the evaporating and condensing surfaces aro large and close together. I t is intended for liquids th a t oxidise or decompose when distilled in air.
N. M. BLicn.
D istillin g apparatus for the chem ical engineer
in g laboratory. W. L. B e u s c h l e i n (Ind. Eng.
Chem. [Anal.], 1929,1,43—44).—An apparatus which combines the batch and continuous-type fraction
ating equipment, and gives constant conditions, con
sists of a 30-gallon still, plate column, and condenser of the usual type, with thermometers in the hand-holc covers of each plate, and in the vapour of the kettle.
Piping from condenser to kettle converts into a continuous process, and the condensate passes through two Venturi meters (one for the reflux and one for the net output), of the two-liquid multiplying type. The reflux ratio is obtained and regulated by a valve, an open vent eliminating siphoning. In operation the condensate composition is built up by returning all as reflux to the kettle, after which a portion is allowed to flow continuously through the sight gravity jar into the kettle, and readings of the Venturi mano
meters, kettle thermometer, and condensate hydro
meter are taken. By directing a fraction of the condensate through a cock to the storage vessel, con
centration may be changed and a new set of conditions
established. J). II. H e w e r .
A pplication of the vacuum tube in the falling- ball m ethod [of determ ining viscosity] for dark- coloured solutions. E. M. Sym m es and E. A.
L a n t z (Ind. Eng. Chem. [Anal.], 1929, 1, 35—36).—
A steel ball is used and the coils of an oscillating circuit are wound in two slots corresponding with the graduation marks of the viscosity tube. The change in note due to the change in frequency of the oscill
ations marks the passage of the ball through the
coils. C. I r w i n .
B rine circulator for cooling condensers. H. T.
Ger r y (J. Amer. Chem. Soc., 1929, 51, 475).—An easily constructed laboratory adaptation of the air
lift pumps used in sulphuric plants is described.
S. K. Tw e e d y. Colorim eter for determ ination of hydrogen- ion concentration. J . J . B e a v e r (J. Opt. Soc.
Amer., 1929, 18, 41—49).—The apparatus described avoids the use of standardised buffer solutions. I t lias an additional cup and plunger and the total depth of liquid in the light path is kept constant irrespective of what this depth or the ratio of the depths of liquid in the two cups may be. The method is rapid and accurate, and it can be used for coloured or turbid solutions if the colour is not too deep. The apparatus can easily be adapted for use as an ordinary colori
meter. N. M. B lig ii.
Suction as a filterin g aid. G. L. H o c k e n y o s (Chemist Analyst, 1928, 17, No. 4, 18).—A pressure regulator, consisting of a tube containing a variable amount of water, and fitted with a stopper carrying a tube to the suction flask and another tube from the water upwards into the air, is recommended.
Ch em ic a l Ab stra cts. P orous filter crucibles. S. G e r i c k e (Chem.- Ztg., 1929, 53, 119).—Porous filter crucibles have a limited application only. U ntrustw orthy results are obtained when such crucibles are used in th e deter
mination of phosphoric acid as magnesium pyro
phosphate or as phosphomolybdate, and the deter
mination of nickel as the dimethylglyoxime compound.
Calcium oxalate and barium sulphate pass through most porous crucibles and filtration of gelatinous precipitates is slow. J . S. C a r t e r .
E bullioscopic apparatus for high-pressure researches. W. S w i e n t o s l a w s k i (Compt. rend., 1929, 188, 392—395).—The author’s differential ebullioscope (this vol., 255) m ay be adapted for work a t pressures up to 25 atm . by the use of compressed nitrogen, the apparatus being placed in gas-tight, steel protecting vessels. Electrical heat
ing and temperature-measuring devices are used, and the pressure is determined from the b. p. of water, which is used as a control, or from the amount of nitrogen in a tube attached to the source of pressure and maintained a t a constant tem perature (cf.
following abstract). J . Gr a n t. M odification of | S w ien to slaw sk i’s] ebullio
scope for high pressures. A. Z m a c z y n s k i (Compt.
rend., 1929,188, 395—396; cf. preceding abstract).—
A reservoir supplied with a siphon is connected to the portion of the apparatus containing the boiling liquid