We may also represent the isovolumetric reaction by (21), then 
the coefficients will have another value. As at the reaction from 
right to left heat can as well be given out as absorbed, the equili- 
brium F4 F’ +4 F”’ can, therefore, starting from r go as well towards 
higher as towards lower temperatures. 
Leyden, Anorg. Chem. Lab. ; (To be continued). 
Chemistry. — “Action of Sunlight on the Cinnamic Acids”. By 
Dr. A. W: K. pe Jone. (Communicated by Prof. P. van 
ROMBURGH). 
(Communicated in the meeting of March 27, 1915). 
Some time ago *) | communicated that «l/o-cinnamie acid is converted 
in sunlight into @-, B-truxillie acid and normal cinnamic acid. 
In a communication as to this photo-action in the Recueil’) I 
drew, in connexion with the progressive change of the transformation 
and also because the addition of normal cinnamic to the a//o-acid 
increased the quantity of g-truxillie acid, the conclusion that B-truxillie 
acid was formed by the combination of one molecule of «/lo-acid 
with one molecule of normal acid. 
For a further study of @-truxillic acid it was of great importance 
to possess larger quantities of the same. 
The preparation may take place from the split off coca acids, or 
from the «/lo-cinnamie acid that has been affected by sunlight. 
The first process is tedious and, from a comparatively large 
quantity of split off acids, it yields but a small amount of g-truxillie 
acid. 
In connexion herewith, attention may be called to the fact that. 
commercial cinnamic acid may often contain not unappreciable 
quantities of g-truxillie acid which very likely has got into it in the 
preparation of the cinnamic acid from the above coca acids (both 
acids possess calcium salts sparingly soluble in water). For instance, 
a product called Ac. cinnamylicum puriss. D. Ap. V. contained 1.8°/, 
and another labelled Ac. cinnamylicum synth. puriss 3°/, of 9-truxillie 
acid, whilst in the Ae. cinnamylicum purum of the same works 
occurred a trace. The g-truxillie acid, being the stronger acid, may 
be readily separated from the cinnamic acid by dilute aqueous 
sodium hydroxide. 
*) Proc. 14, 100 (1911), 
2) R. 31, 258 (1912). 
