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of the nitroproducts formed in the latter case is to be calculated 
from the former case. In the first place we should bear in mind 
that the energy of the substances we start from is different, and now 
it is true that this energy is cancelled in tbe determination of the 
relative quantities, yet the energy of the intermediate states may 
depend on this energy. To obtain an answer to the given questions 
we should therefore have to introduce a hypothesis concerning the 
energy quantities. | 
These hypotheses must necessarily be very arbitrary, as analogies 
with other phenomena are not yet known for them. One of the 
most plausible hypotheses would in my opinion be the following: 
Let us denote the energy required for the substitution of the NO,- 
group for the hydrogen atoms in the benzene molecule by «,. Then 
the energy for substitution of tne hydrogen atoms in toluene and 
chlor benzene resp. may be represented by €,+ &,, & HE, & + tp 
resp: €, ++ €,, &,-+ Em, and &, He, 
If we now think a substitution carried out in the molecule ortho- 
chlortoluene, we might assume that the energies required for every 
substituable place must be added 
CH, 
a/ NCI 
ok 
b 
For substitution at the place @, which is in an ortho-position with 
respect to chlorine and in metaposition with respect to CH,, an 
energy quantity ¢, + En, +, would then be reqnired. Reasoning 
in an analogous way &,.+ &,, + &,, would be required for the place 6. 
Applying equation 5, we get: 
kp Ea Sb ty (E‚ + Em, + fe, a ewe Eph Ems) 
In == == neeh = 
ka RL RT 
pe (&n,—&), )— (&m.— €o, ) 
Bettie ghee chew 
When we now consider that the introduction of the second sub- 
stituent requires: 
we find easily by combination of the three equations: 
