TRANSACTIONS OF SECTION B. 499 
and about a metre in length when unwound. Platinum termjnals were sealed in 
at each end of the spiral. 
The liquid amalgam in the spiral was allowed to cool slowly and to solidify 
in the capillary tube, care being taken to preserve the continuity and uniformity 
of the thread. 
The resistance was measured by a potentiometer method. About twenty 
amalgams have been examined, the composition varying from 0 to 45 atoms per 
cent. of mercury. 
The resistances varied from 0°05 to 0'4 ohm, and the specific conductivities from 
18 x 10-4 to 19. xX 10-4, The resistances were measured at a temperature of 
15° C. The curve obtained by plotting specific conductivities as ordinates and 
atomic percentages as abscissee shows two discontinuities and a minimum point. 
The breaks occur at 85°5 and 779 atoms per cent. of sodium, and the minimum 
point at 65 per cent. sodium. ‘The thermal diagram has breaks at 85°2, 71°7, and 
63°3 per cent, sodium. 
7. Discussion on the Significance of Optical Properties. 
(1) Optical Rotatory Powers and Dispersions of the Members of some 
new Homologous Series. By R. H. Pickarp and J. Kenyon. 
The authors have synthesised the optically active forms of over 100 compounds 
belonging to the following ten series: (1) Methyl alkyl carbinols, Me.CHOH.R, 
(2) esters of methyl ethyl carbinol and normal fatty acids, MeEt.CH.O.COR, 
(3) esters of methyl n-butyl carbinol Me(C,H,)CH.O.COR, (4) esters of methyl 
n-amyl carbinol Me(C,H,,)CH.O.COR, (5) esters of methyl n-hexyl carbinol 
Me(C,H,,)CH.O.COR, (6) esters of methyl n-nonyl carbinol Me(C,H,,) 
CH.O.COR, (7) acetates of methyl n-alkyl carbinols Me.R.CH.O.COCH,, 
(8) n-dodecoates of the same Me.R.CH.O.COC,,H,,, (9) ethyl alkyl carbinols 
Et.CHOH.R, (10) isopropyl alkyl carbinols Me,CHOH.R. (In each series 
the ‘ growing chain’ is normal and not branched.) 
All these compounds possess simple and closely related constitutions, but no 
numerical relationship between their rotatory powers has as yet been detected. 
The optical rotatory and dispersive powers of the compounds show well-marked 
regularities, which are more or less common to all the series. The most pro- 
nounced of these is that due to the special stereochemical configuration of that 
member of an homologous series in which the growing chain (R or-COR in the 
above formule) contains five carbon atoms, 
(ii) Rotatory Dispersion. By T. Martin Lowry, D.Sc. 
Attention was directed to the importance of making measurements of optical 
rotation over a range of wave-lengths, instead of merely with light of one 
colour. ‘This is specially necessary in the case of substances, such as derivatives 
of tartaric acid, in which anomalous rotatory dispersion is known or may be 
suspected to exist. 
After experiments extending over a period of seven years, the methods of 
measuring rotatory dispersion have been so simplified that they are now within 
the range of the ordinary advanced student, and should soon become a regular 
part of the ordinary routine of the laboratory. For many purposes it is 
sufficient to take readings with the green and violet mercury lines, but sodium 
and lithium may also be used in order to see whether the curve of rotatory 
dispersion has the normal form. A still more valuable check is provided by 
readings taken with the red and green cadmium lines, but these require more 
complex apparatus and cannot yet be regarded as generally available. 
The examination of the optical and magnetic rotatory dispersion of some 
fifty organic liquids has shown that the curve of rotatory dispersion has an 
extremely simple form. It can be expressed by the equation 
k 
24S OO 
a — A? 
