848 



from which .v = 0.96. Hence, the result is here CI : Br = 1 : 0.96. 

 The mean result of these two experimental series is therefore: 

 CI : Br :^ 1:0.88. 



The nitra'.ion oï p-chloroiixlolx'iizi'iw caused the separation of large 

 quantities of iodine with forinati(Mi of /v-chloronitroben/ene. Hence, 

 for my purpose it was unsuitahle. 



In the nitration oï o-cliloroiodohtnizene, there was also some separation 

 of iodine, but the formation of o-chloronitrobenzene did not amount 

 to more than about 37u- When determining' the proi)ortion in whicii 

 CI and I were separated from the nitration product by NaOCH^ a 

 correction for this must therefore, be applied. For the velocity ratio 

 CI : I was thus found the mean value of 1 : J. 84. 



It uow^ became interesting to also investigate the nitration product 

 of o-bromoiodo benzene quantitatively as to its components. For, as 

 CI: Br was found =1:0.80 and CI : I = 1 : 1.84, Br : 1 should 

 be = 1 : 2.30, if indeed the two halogens present, act (piite indepen- 

 dently of each other. 



Also in this nitration a little separation of iodine took place; the 

 content of o-bromonitrol)enzene in the nitration |)roduct was in 

 this case 4.47o- Applying a correction for this the mean ratio 

 Br : I =: 1:1.75 was found, which rathei- ditfers from the calculated 

 tigure. If, however, we calculate the percentages of the isomerides 

 with the ratios 1.75 and 2.30 the theoretical value gives 69.77o of 

 the isomerides Br, I, XO^ ^ i, 2, 3 -]- 1, 2, 5, and the experimental 

 value 63.6"/,, which may i)e considered as a suflicient a[)proximation 

 if we bear in mind the difliculties of these (piantitative determinations. 



The conclusions from the above ai-e obvious. Since it has 

 appeared that two substituents simultaneously present in ortho- and 

 in parapositions do not sensibly interfere with their respective 

 actions in legard to a third enteiing group, we shall be able to 

 calculate from the ligures now found \\'\{\\ sufticient probability in 

 what proportion are formed the isomerides of other conq)Ounds, for 

 instance in the nitration of o- and of p-bromotoluene. 



The above mentioned order of the substituents towards the decreasing 

 substitution velocity caused by the same now becomes : 



OH > NH, > I > CI > Br > CH,. 



Hence, the ratio OH : NHj and NH., : I still remains to be deter- 

 mined. As, however, in the nitration of the iodoanilines great difli- 

 culties may be expected, A. F. H. IjObry dr Bruyn has taken 

 in hand a quantitative research of the nitration of o- and /;-chloro- 

 aniline in the aljove direction. As a preliminary result of his experi- 



