23 
1918-19.] Researches in Optical Activity. 
family of T-R curves. If this be so — and there is much evidence in 
favour of the idea — quinoline must be regarded as a more powerful solvent 
for this ester than is cinnamic aldehyde, since the shifting of the T-R 
curve is apparently much greater in the former than in the latter case, and 
Temperature. 
20° 40° 60° 80°' 100° 120° 140° 
Fig. 2. — Temperature-rotation curves for ethyl tartrate in cinnamic aldehyde, 
p = 9 ‘64 (heavy lines), and in quinoline, p — 13 601 (thin lines). 
it is at least quite possible, indeed it is very probable, that if the quinoline 
solution were examined at lower temperatures than those for which the 
diagram applies, the quinoline curves would rise to higher values than 
those for cinnamic aldehyde. This is also in agreement with the fact 
that whereas the C-R* curve for ethyl tartrate in quinoline shows a 
* Concentration-Rotation. 
