( 252 ) 



which plainly shows Ihe contraction which takes place on mixing 

 the isomers, by the higher sp. gr. which the mixtures possess, in 

 comparison with the calculated values (the straight line). 



loot do 6 o <*o Zo 



Fig. ± Line <>f the specific gravities of ortho- and para-nitrotoluene. 



The nitration of toluene was carried out by the method of Bktlstehs 

 and KüHLBERG, (A. 158, 348), i.e. the nitric acid being added to the 

 toluene and not reversedly, because, by their method, the formation 

 of dinitro-products is entirely avoided. The toluene employed had a 

 constant boiling point (llO^.tt at 760 mm.) and had been purified by 

 being boiled with sodium wire in a reflex apparatus. 



The nitration of the purified toluene took place at the temperature 

 of -30°; 0°; -f 30° and +60° and was carried out as follows: 



75 grams of the toluene were placed in a small flask and brought 

 to the required temperature. 200 c.c. of nitric acid (sp.gr. 1.475) were 

 slowly dropped into the toluene, the mixture being stirred mechani- 

 cally. Immediately after the addition of the first drops of the acid 

 the liquid turned intensely brownish-red ; so that it was not possible 

 to see whether two liquid layers or one homogeneous mixture was 

 formed. The heat evolved during the nitration was but trifling;, at 



