126 
MR. A. E. OXLEY ON THE INFLUENCE OF MOLECULAR 
the space occupied by the substance) during a repetition of this experiment, it was 
discovered that the benzaldehyde had not crystallized but had passed into a trans¬ 
parent jelly-like mass. By plunging the phial containing the benzaldehyde into liquid 
air, the benzaldehyde again assumed this jelly form, but on warming, followed by a 
further slight cooling, a white crystalline mass was obtained. This was now cooled to 
the temperature of liquid air, withdrawn, suspended from the torsion balance and 
quickly surrounded by liquid air. An experiment carried out on the benzaldehyde 
after this treatment is shown in fig. 10, Curve A'B'BC. It will be seen that 
approximately the normal dip, 5 per cent., was obtained, the liquid being more 
diamagnetic than the crystals, but the transition stage was considerably drawn out 
and appeared to have an intermediate step or stable state. 
Shortly after this difference in magnetic property between the gelatinous and the 
crystal] ine states of benzaldehyde had been established, a research appeared by 
M. Chaudier,* who had discovered that the specific magnetic rotation of organic 
substances behaves in a similar way. He found that if the substance passed into a 
gelatinous state, on being cooled below the normal fusion point, there was no 
discontinuity of the magnetic rotation in passing from the liquid to the gelatinous 
state. The rotation, on the other hand, disappeared totally if the substance passed 
into a crystalline form on being cooled. The two phenomena—magnetic rotation and 
magnetic susceptibility—are doubtless closely allied and each is affected by a transition 
from the liquid to the crystalline state. An attempt is made in Part II. to connect 
theoretically these effects. It does not appear that Chaudier obtained the same 
substance in both gelatinous and crystalline forms, and it would be interesting to carry 
out an experiment on the magnetic rotation of a substance capable of existing in 
either form at a given temperature. Chaudier shows that the discontinuity exists 
for benzene, aniline, and nitrobenzene on crystallization, and that the rotation remains 
constant in the cases of amyl-alcohol, glycerine, and essence of terebene, which pass 
into the gelatinous form on cooling below the normal freezing point. The phenomenon 
with the last substance is made complex on account of optical activity. 
Benzene, i . 
\/ 
This substance shows an anomaly different from that of any other benzene compound 
investigated. Five experiments have been made and one of the curves is drawn in 
fig. 11. The pit in the curve occurs in every case at the normal fusion point, 
5° C. On either side of this point, the curve rises, the distant parts of the curve 
corresponding to the liquid and crystalline states being continuous, as shown by the 
dotted line. This dotted line appears to correspond to no real physical state as it was 
found impossible to make the substance pass along this path. The depth of the pit 
* ‘ Comptes Rendus,’ vol. 156, p. 1529, May, 1913. 
