increasing velocity of flow. The double refraction is less in old sols, which is contrary to the behaviour of sols previously investigated. The double refraction is also reduced by mechanical agitation of the s o l ; it is increased by addition of colouring matters, the
934 BRITISH CHEMICAL ABSTRACTS.— A.
amount depending on the nature of the colouring substance. The elasticity and viscosity of both colourless and coloured sols are parallel with the double refraction. It is claimed that these sols are the prototype of a new class of colloids. In general, they are hydrophilic and belong to the class of colloidal electrolytes. Addition of electrolytes has a different effect from that usually observed. The influence of the cation does not follow the Hofmeister series, but depends on the solubility relations of the salts.
E. S. He d g e s.
D epend en ce of th e A vogad ro n u m b er on size of p a rticle s. S. Ra y (Z. physikal. Chem., 1927, 128, 182— 188).—Theoretical. It is suggested that the reason why Perrin’s method of determining the Avogadro number from measurements of the density of colloidal solutions gives uniformly higher values than Millikan’s method is to be found in the dependence of the number on the size of the particles, an effect which is eliminated in the latter method.
An examination of the results of Porter and Hedges (A., 1923, ii, 743) lends support to this view.
R. Cu t h i l l.
In terference m ic r o sc o p ic a l m e th o d fo r th e m e a su r e m e n t of s m a ll p a rticle s of 150 d ia m eter. U. Ge r h a r d t (Z. Physik, 1927, 44, 397— 402).—The technique developed by the author (ibid., 1926, 35, 697—717) has been extended to the measurements of particles of 150 ¡ah diameter.
Examples of photographic records are described and
discussed. R. W. Lu n t.
D eterm in a tio n of d isp er sio n of p ro tected m e ta l so ls. F. He b l e r (Pharm. Ztg., 1927, 72, 1013— 1014).—The colour and metal content of an ultrafiltrate do not afford conclusive evidence relative to the degree of dispersion of a sol; the ultramicro
scope is trustworthy for single determinations, and for a large number a nephelometric method can be
recommended. S. I . Le v y.
D e n sity an d sp ecific o p tica l ro ta tio n of so lu tio n s of a lb u m in . H . Je s s e n- Ha n s e n (Compt.
rend. Lab. Carlsberg, 1927, 16, No. 10, 1—20).—The density of crystalline egg-albumin in ammonium sul
phate solutions has been derived from the density of these solutions on the assumption, justified by experi
ment, that egg-albumin in aqueous or salt solution may be regarded as a two-phase system miscible without volume change, the hydrated protein constituting the disperse phase. The results show that the density of the hydrated protein in a solution of ammonium sulphate of given concentration decreases slightly as the concentration of ammonium sulphate is increased.
Data are also given referring to the density of hydrated egg-albumin in ammonium sulphate solution as a function of the p a in the range p & 4-1— 5-4.
The specific optical rotation of solutions of egg- albumin in solutions of ammonium sulphate has been determined for the C, D, E, and F lines. The specific rotation does not appear to depend on the con
centration of ammonium sulphate, but it increases slightly as the concentration of the protein is diminished. Unless bacterial decomposition sets in the specific optical rotation is practically constant between 11-5° and 29°. The optical rotation of
various samples of crystalline egg-albumin in solution in ammonium sulphate varied from [a]D +31-64° to
29-92°. E. A. Lttnt.
V isc o sim e tr y in th e stu d y of co llo id a l clay.
A. De m o l o n and G . Ba r b i e r (Compt. rend., 1927, 185, 542—545).—Viscosimetric measurements on colloidal suspensions of clay are of value only when made under comparable conditions. The suspensions (prepared by dialysis of decalcified and washed brick-earth) do not obey Poiseuille’s law. The viscosity increases as a hyperbolic function of the concentration, but diminishes rapidly with rise of temperature. The effect of a flocculating electrolyte increases rapidly to a maximum with the amount added, and falls off slowly, the curve showing no anomaly at the flocculation point. Nitrates and chlorides have the same flocculation effect, sulphates less, and sodium salts the least influence. The permeability of the coagulum increases continuously with the concentration of electrolyte. The phenomena are explainable by the production in the colloidal clay of aggregates of variable size, the greater aggregates having the maximum permeability. J. Gr a n t.
V isco sity and h yd ra tio n of dye solutions.
S. Li e p a t o v (J. Russ. Phys. Chem. Soc., 1926, 58, 1321— 1333).—See A., 1926, 903.
V isc o sity and g el-fo rm a tio n of eerie hydroxide so ls . D. N. Ch a k r a v a r t i, S. Gh o s h, and N. R.
Di i a r (Z. anorg. Chem., 1927, 164, 63—68).—
Dialysis of solutions of eerie ammonium nitrate prepared in the cold yields sols of eerie hydroxide which are readily transformed into gels by electro
lytes. These sols have the properties characteristic of hydrophilic colloids, viz., with increasing age the conductivity diminishes and the viscosity increases, and the viscosity increases rapidly with increasing concentration. H the eerie ammonium nitrate solutions are boiled before dialysis, the residting sols will not pass into the gel state, and are of a distinctly hydrophobic character. For both kinds of sol, the coagulative power of the fluoride ion is very much greater than that of the chloride ion, being approxim
ately equal to that of the sulphate ion, which would seem to indicate that the fluoride ion is bivalent.
R. Cu t h i l l.
In fluence of g u m acacia on th e sp ecific con
d uctan ce of s o m e b in a ry elec tro ly te s and th e
effect of b in a ry elec tro ly te s on th e visco sity of g u m acacia so lu tio n s. J. F. S p e n c e r and (Miss) R. D r u m m o n d (Kolloid-Z., 1927, 42, 332—335)-—
The experiments differ from most others on the influence of colloids on the specific conductance of electrolytes in that gum acacia itself has a con
siderable conductivity. Measurements were made of the viscosity of solutions of gum acacia at various concentrations, and of the effect of progressive addition of hydrochloric acid, sodium chloride, and barium chloride. In all cases, the viscosity was reduced b y the presence of the electrolyte. With solutions of gum acacia under 10%, a minimum viscosity was obtained in presence of 0-2Ar-h y d ro -
chloric acid. For stronger solutions of the colloid, the viscosity fell continuously with increasing con
centration of hydrochloric acid. All concentrations
of gum acacia showed a minimum of viscosity in presence of O-liY-sodium chloride and also in presence of 02iV-barium chloride. Measurements of the conductivities of gum acacia mixed with each of the same electrolytes gave in all cases a result lower than the sum of the conductivities of the colloid and the electrolyte. In presence of hydrochloric acid weaker than 0-5iV, the change of conductivity with increase of concentration of the colloid passes through a minimum value, the position of which depends on the concen
tration of acid. The results suggest that a certain amount of the solvent is bound. Ageing of the gum acacia solution caused no appreciable difference in the effect of electrolytes on the viscosity or conductivity.
E. S. He d g e s.
A ction of X -r a y s on collo id s. J. A. Cr o w t h e r
and J. A. V. Fa i r b r o t h e r (Phil. Mag., 1927, [vii], 4, 325—335).—The effects of -radiation on iron, copper, silver, and gold sols have been studied. It has been found that positively-charged iron and copper sols are coagulated by irradiation, whilst the negatively-charged gold and silver sols are further dispersed and their stability is increased. The effect has been studied numerically for a copper sol prepared by Bredig’s method and the results suggest that the coagulation is due to ionisation produced in the diffuse double layer surrounding the particles.
A. E. Mi t c h e l l.
Influence of co llo id s on th e rea ctio n of a solution of elec tro ly te s. H y d r o ly sis of g lu c o s- ides b y a n im a l m e m b ra n es. J. Lo i s e l e u r (Bull.
Soc. Chim. biol., 1927, 9, 785—801).—When animal membranes are introduced into a solution of sucrose containing an electrolyte, hydrolysis of the sugar takes place. This is attributed to the preferential adsorp
tion of one type of ion on the surface of the membrane, the alteration of p a which results causing the hydro
lysis of the sugar. W. 0 . Ke r m a c k.
Drop n u m b er and em u lsifia b ility . R . C. Sm i t h
and (Mi s s) I. C. D ow (J. Physical Cliem., 1927, 31, 1263—1266).—The relation between drop number and emulsifiability has been investigated for various oils and water. Emulsifiability implies ease of emulsific- ation and also stability of the resulting emulsion, and the drop number measures only the first factor and hence is not a true indication of emulsifiability.
L . S. Th e o b a l d.
Phenom ena a sso cia te d w ith th e h yd ra tion of myelin. G. Fr i e d e l (Compt. rend., 1927, 185, 330—332).—The phenomena associated with the hydration of purified myelin have been examined by polarised light, and found to be similar to those characterising the hydration of soaps.
E . A. Lt jn t.
Vibrating soap jelly. E . H. Bu c h n e r (Nature, 1927, 120, 367).—Soft soap appears to crystallise on keeping to a network of crystal fibres sufficiently rigid to permit sound vibration. A. A. El d r i d g e.
, Structure of g e ls. C r y sta llisa tio n of /-arab - mosazone. P . Th o m a s and (Ml l e.) M . Si b i
(Compt. rend., 1927, 185, 540—542; cf. A., 1926,
>W3).—By the addition of a suitable foreign gummy substance, the crystallisation of arabinosazone has wen modified in such a way as to lead to the form
ation of a pseudo-gel. The general nature of this phenomenon is indicated. Concentrations of gum exceeding 1% of the sugar present gradually tend to change the crystals from radiating tufts of short non- flexible needles to very long hair-like filaments, which hold the liquid in their interstices and produce a gel
effect. J. Gr a n t.
F u nction of w a te r p rese n t in silic ic acid g e l.
S tru ctu re of s ilic ic acid g el. H. A. Fe l l s and J. B . Fi r t h (J. Physical Chem., 1927, 31, 1230—
1236).—The state of combination of the water con
tained in a silicic acid gel has been followed by desicc
ation over sulphuric acid. The amount of water withdrawn in this way, before crystals of sodium chloride appear, increases as the gel increases in age, indicating that the water available as solvent for this salt is increasing. These results lead to the conclusion that the water in the gel exists as (1) “ fixed ” water, which is associated with the silica of the gel, and (ii) “ free ” water, which is mechanically enclosed and is available as solvent for the sodium chloride. The process of ageing then consists in the change of the ratio of “ fixed ” to “ free ” water. A newly-formed gel consists of molecules of heavily hydrated silica which slowly crystallise, liberating water and leaving a loose, mesh-like structure which finally, in the dried gel, becomes of a capillary nature.
L. S. Th e o b a l d.
D iffu sio n -p o ten tia l m e a su r e m e n ts a p p lied to h yd roch lo ric a c id -g e la tin s y s te m s . I. E q u iv alen t w e ig h t of g ela tin . A. L. Fe r g u s o n and E. K. Ba c o n (J. Amer. Chem. Soc., 1927, 49, 1921—
1934).—A cell arrangement permitting the approxim
ate determination of static liquid-j unction potentials, is described and measurements on hydrochloric acid systems, with and without sodium chloride and gelatin, are recorded. The reaction between hydro
chloric acid and gelatin is stoicheiometric and purely chemical in nature. From the position of the cusps, on the diffusion potential-concentration curves the equivalent weight of gelatin is found to be 1090.
S. K. Tw e e d y.
D iffu sion -p o ten tia l m e a su r e m e n ts ap plied to h yd roch lo ric a cid -g e la tin s y s te m s . II. C om p on en ts of h yd ro ch loric a c id -g e la tin solution s..
E. K. Ba c o n [with A. L. Fe r g u s o n] (J. Amer. Chem..
Soc., 1927, 49, 1934— 1939).—A consideration of the diffusion-potential curves of hydrochloric acid-gelatin solutions indicates that the components of such solutions must be defined in terms of free acid, com
bined and uncombined gelatin, and that the solution contains highly-ionised gelatin chloride.
S. K . Tw e e d y.
C oagulation of co llo id a l su lp h u r so lu tio n s. G ..
R o ssi (Zymologica, 1927, 2, 63—72).—The adsorptive action of colloidal sulphur on the ions derived from stabilising electrolytes varies with the temperature.
Since coagulation occurs when the temperature is.
raised, it would seem that there is a close connexion between the adsorption of ions and the stability of colloidal solutions. Experimental data are given which support this view. T. H. Po p e.
P ro tein co ag u lation in d rop s. IX . S y n e r g is m of p ro te in s in m ix tu r e s . F. Bohm (Biochem..
936 BRITISH CHEMICAL ABSTRACTS.— A.
Z., 1927, 187, S4—91).—Mixtures of an albumin with a globulin show precipitation reactions, with various coagulants, of the type characteristic of globulins. The precipitation number of such a mixture, whether artificial or natural, is the arithmetic mean of the precipitation numbers of the components, provided that allowance is made for the presence of other dissolved substances in the natural mixtures.
Egg-white and serum-protein have approximately identical precipitation numbers. The numbers for globulins are in descending order of magnitude for edestin, egg-white, and serum-globulins, whilst serum - albumin has a,higher number than egg-albumin.
C. R . Ha r i n g t o n.
T h erm o d y n a m ic n e c e ssity of g a s d egen eration . N. d e Ko l o s o v s k i (Physikal. Z., 1927, 28, 475—
476).—I t is shown that the specific heats of gases at constant pressure and also at constant volume vanish at the absolute zero. Hence, it follows that gas degeneration is a necessary concomitant of the third law of thermodynamics. W. E. Do w n e y.
N e r n st’s h ea t th eorem . J. J. v a n La a r (Chem.
Weekblad, 1927, 24, 302— 311).—The theorem is attacked, and condemned as wholly fallacious, since it is based on the assumption that relations which hold to a reasonable degree of approximation at very low temperatures (Kirchhoff’s formula) are valid also at much higher temperatures. The theorem in its original form does not give the correct trans
formation point of sulphur, for example, and it is shown that only by modifying tho theorem, and employing a value for the constant which presup
poses the temperature, is it possible to arrive at the correct figure, 96°. S. I. Le v y.
A b so lu te zero of en trop y and in tern a l en ergy.
J. E. Ve r s c h a f f e l t (Phil. Mag., 1927, [vii], 4, 335—
337).—The author is in disagreement with Kleeman (this vol., 520) with regard to the axiomatic character of the third law of thermodynamics and the conse
quences arising from this. A. E. Mi t c h e l l.
P ro p er ties of su b sta n ce s and m ix tu r e s in th e con d en sed sta te a t th e a b so lu te zero of te m p e r atu re. R. D. Kl e e m a n (J. Physical Cliem., 1927, 31, 937—947; cf. this vol., 520).—Further relation
ships are derived. L . S. Th e o b a l d.
Q uan titative tr ea tm e n t of d ev ia tio n s fro m R a o u lt’s law . J. H . Hi l d e b r a n d (Proc. Nat.
Acad. Sci., 1927, 13, 267—272).—For each solute (mol. fraction iV2) most solvents yield a family of curves log IV2= /(1 ¡T) (cf. Mortimer, A., 1923, ii, 299).
Solutions conforming to such a fam ily of solubility curves are termed “ regular.” In the case of regular solutions the existing solubility data are accounted for by an extension of Raoult’s law, viz., log£ a2—
\oge N 2-\-(bN^IRT), where 6 is a constant which can be calculated from internal pressures or otherwise and fl2 is the activity of the solute. Several corollaries of the equation are deduced, e.g., the partial molal heat of mixing of the solute is — 6Ar12. The equation may also be deduced from van der Waals’ equation
of state. S. K. Tw e e d y.
S to r c h ’s equation, a g en er a l d ilu tio n fo rm u la, an d th e va lid ity of th e la w of m a s s a ctio n a t
lim itin g d ilu tio n s. A. Fe r g u s o n and I. Vo g e l
(Phil. Mag., 1927, [vii], 4, 1— 17).—Examination of the data for nineteen electrolytes has shown that Storch’s equation, in its simple or in a general
ised form, represents satisfactorily the relationship between the degree of ionisation and the concentration over a wide range. Ostwald’s dilution law holds for only two of the electrolytes examined.
A. E. Mi t c h e l l.
C alcu lation of a ctiv ity coefficien ts fr o m con
d u ctiv ity m e a su r e m e n ts. C. W. Da v i e s (Phil.
Mag., 1927, [vii], 4, 244—250).—Tho mean activity coefficients for a number of uni-univalent acids have been calculated from conductivity measurements.
The results vary from 0-35 to 0-44 and include the follow ing: formic acid 0-382, acetic acid 0-393, cyanoacetic acid 0-372. The value for the series of acids is considered to be 0-38 ¿0 -01. This is in agreement with the value for hydrochloric acid obtained by Randall and Vanselow (A., 1925, ii, 33) and by Nonhebel (A., 1926, 1006). The value for uni-univalent electrolytes required by Debye and Hiickel’s theory is 0-5 and by Milner’s is 0-37, so that these results tend to support Milner’s theory.
A. E. Mi t c h e l l.
F a cto rs d ete rm in in g th e d isso lu tio n of electro
ly te s and th e ir co n d ition in solu tio n . I. K . Fr e d e n h a g e n (Z. physikal. Chem., 1927, 128, 1—24).—The electrical properties of solutions of electrolytes in various solvents have been examined.
The normal potentials of the halogens in ammonia are: fluorine, 0-77; chlorine, 1-06; bromine, 1-26;
and iodine, 1-51 volts; the potential of the nitrate group is greater than that of iodine, whilst that of the hydroxyl group is less than that of fluorine.
The value for the nitrate group in ammonia is approximately the same as in water, whilst that for iodine is much greater than, and th at for fluorine much less than the corresponding figure in water.
The electrolytic solution pressures of the alkali metals are much smaller in ammonia than in water, but the saturation concentration of the alkali halides is influenced markedly only by the solution pressure of the anion.
The preparation of pure hydrogen fluoride is described; its specific conductance is 0-4 x 10'1 mho at 0°, and its dielectric capacity 83-6 at 0°, 110-6 at - 2 7 ° , 134-2 at - 4 2 ° , 173-2 at - 7 0 ° , and 174-S at
—73°. Measurements of the conductivity of methyl alcohol and of water in hydrogen fluoride solution indicate that in this solvent the latter is the stronger acid. The groups OH, N 0 3, S 0 4, C103, B r03, I03, C104 exhibit an unusually great solution pressure in hydrogen fluoride, whilst that of the halogens is very small.
Hydrogen cyanide, despite its high dielectric con
stant, is a less powerfully ionising solvent than water, methyl alcohol, ethyl alcohol, ammonia, or hydrogen fluoride; the solution pressures of all the substances investigated are very small. The solvent and ionising powers of a number of compounds are compared and discussed. H. F. Gillbe.
F a cto rs d e te r m in in g th e d isso lu tio n of electro
ly te s an d th e ir co n d itio n in so lu tio n . II.
K-Fr e d e n h a g e n (Z. physikal. Chem., 1927, 128, 239—
265).—It is shown thermodynamically that the electrolytic solution number (electrolytic solution tension/concentration) of an element in a particular solvent is a function of the affinity of the element for the ions resulting from the dissociation of the solvent and of the internal forces. The element assumes a positive or negative charge in the solution according as its affinity for the anion of the solvent is greater or less than its affinity for the cation.
These conclusions are in harmony with the data previously obtained (cf. preceding abstract) for the electrolytic solution tension of elements in various solvents. If a compound is in equilibrium with its ions in a solution and with its neutral atoms in the vapour phase, the dissociation constant in the liquid phase, IC, is related to that in the vapour phase, K , by the expression where k x and Jc2 are the distribution ratios of the ions and ks is that of the undissociated compound. This equation is found to be applicable with a fair degree of accuracy to aqueous solutions of the hydrogen halides. Other things remaining the same, the dissociation constant in the liquid phase depends on the electrolytic solu
tion numbers, and as these are high for metals the almost complete dissociation of neutral salts is explained. The slight effect of temperature change on electrolytic dissociation is attributed to the opposite effects of temperature on the dissociation constant in the gas phase and on the electrolytic distribution ratios. It appears probable that the above equation is valid even for solutions of the strong electrolytes, deviations from the dilution law in dilute solutions being due to increase in the electro
lytic solution numbers with increasing concentration, these numbers depending on the internal forces of the
solution. R . Cu t h t l l.
B oric acid s an d th e ir a lk a li sa lts. I. F ree boric acid s. II. A lk a li b o ra te s in aq u eou s
B oric acid s an d th e ir a lk a li sa lts. I. F ree boric acid s. II. A lk a li b o ra te s in aq u eou s