1029 
The first thing to do here must be an orientating investigation to 
see which combinations of substituents give rise to the mobility of 
one or more of the same when they are examined under exactly 
the same conditions. It is, of course, impossible to include all the 
5089 compounds C,H,AB and C,H,ABC, of which 4727 have never 
as yet been tested in any way as to substitution, and of which a 
good many are sure to be still unknown, in such an orientating 
investigation. A choice had to be made. It appeared to me desirable 
to start with a gauging of the intricateness of this problem by (1) 
measuring in a complete set of isomerides the velocity of the trans- 
formation; (2) to do this for two different substances acting thereon; 
(3) to execute this at different temperatures. From this would then 
be shown in the tirst place the influence of the position of the 
substituents. In the second place it would show whether there exists 
a definite ratio between the constants when working with different 
reagents and in the third place whether that ratio also remains 
permanent at various temperatures. If this really were so this would 
cause a considerable simplification of the problem. We then would 
only have to work at a well chosen temperature and with a ditto 
reagent to generally obtain comparable velocity constants. 
The subjomed investigation of Dr. pr Moois briefly described here 
has taught, however, that the said ratio does not exist either for 
temperature or for difference in reagent. This shows that the sub- 
stitution problem possesses such a degree of complicateness that an 
accurate insight therein is still a matter of the distant future. 
As objects for the research of Dr. pre Moois were chosen the six 
isomeric nitrodichlorobenzenes. All these are comparatively readily 
Cl 
Orel 
prepared in quite a pure condition; only for the isomeride | | 
NOANDE 
an easier process of preparation had to be discovered and was 
successfully worked out. 
He brought these six isomerides in contact with absolute-methyl- 
alcoholic solutions of sodium methoxide and of diethylamine, isolated 
all the products of transformation and determined the velocity con- 
stants at three different temperatures. The symmetric isomeride gave 
with methoxide a complicated reaction product consisting presumably 
of azoxycompounds ; diethylamine did not act on it on heating for 
seven days at 110°, so that with this isomeride no velocity measure- 
ments could be carried out. 
