( 303 ) 
With Fagus sylvatica where Tarveer *) found methylsalicylate only 
in the germinating plant, the latter method showed that it was also 
present in the full-grown plant. Methylsalicylate is to be found 
sporadically in the buds of the beech shortly before budding, during 
that process it is found in the young leaves and shoots as well as 
in the branches of the preceeding year. Young long branches are 
richest in it, 0.02 pCt. As soon as the leaves have unfolded, this 
substance begins to disappear again and is nowhere to be found in 
a week’s time. 
Further particulars to be looked for in the dissertation to appear 
shortly. 
Physics. — “Some observations on the course of the molecular 
transformation.” By Prof. J. D. van per Waars. 
As is well known, acetic acid may be considered as a mixture 
of simple and double molecules and we find a decreasing number 
of double molecules when we investigate the saturated vapour of 
this substance at increasing temperature. The same applies also to 
NO,. We are apt to conclude from these two best known instances 
of molecular transformation that this course is the only one that 
is possible. We may, however, easily convince ourselves that also 
the opposite course may occur, and it appears to me that we may 
conclude from figure (1) of the communication of Prof. H. W. 
BakKrvis RoozrBoom in the Proceedings of the previous session, that 
for the transformation of acetaldehyde and paraldehyde this opposite 
course perhaps occurs. 
Let us take the equation for the molecular transformation, as it 
occurs Cont. II, pag. 29, namely: 
vb UE -E) 2(H,—H,) 
log en En +] — — 
“ (1—2)? RT | I, 
The quantity 1—v of this equation represents the quantity of the 
substance expressed in grams which occurs in the form of simple 
molecules, « therefore that which occurs in the form of double 
molecules. If molecules were formed consisting of 7 simple mole- 
cules, the equation would be modified into the following one: 
(v—byr—la A 
log ——_——- = + B. 
(le) il, 
It is true that we only find the equation in this simple shape if 
1) Tattteur, Comptes Rendus A, Sc. Tome 132 p. 1235. 
