( ftltö ) 



solidifying poinl of -|- 2°. 8, this would have been 5°. 2 if no iiuia- 

 compound were present, from which il follows thai 42.2" of para- 

 and 57.8% of ortóo-nitrotoluene must have formed. 



Applying this manner of calculation to the other mixed nitration 

 products wc found them to possess the following composition : 

 Nitration at °/ para " „ ortho % mela 



-3Q° initial solidifying point + 4°.l 41.7 55.6 2.7 

 end ,, ,, — 16°.6 



0° initial „ „ + 2°.8 



end „ „ -16°.8 



-f 30° initial „ „ + 1°.4 



end „ „ — 16°.9 



+ 60° initial „ „ 0°.8 



end ,, ,, — 17°. 4 



If the end solidifying point of the nitration product prepared at 

 0° is taken as ISM, namely, the mean of the figures found after- 

 wards, the mela content increases and amounts to 5.3 %• There 

 remains, therefore a doubt ot about '1° in regard to the quantity 

 of mt'ta compound present in the nitration product, if on the one 

 hand we accept the mean of van den Akknd's values as the true 

 solidifying points, and on the other hand the average values of the 

 other investigations. But also for another reason the quantity of the 

 ///-compound cannot be determined more accurately. 



In the above calculation various surmises have been made. It is 

 for instance, supposed that, at least over the first course, the line 

 which connects the binary eutecticum of ortho- and para-nitrotoluene 

 with the ternary eutecticum is a straight line. It has also been taken 

 for granted that the fall of the initial solidifying point is proportional 

 to the addition of small quantities of a third isomer. An exact deter- 

 mination would be possible only when the entire ternary melting 

 figure were constructed; yet the method as applied here gives a 

 satisfactory approximation as will be seen from ;i survey of Fig. 3. 

 In the plane OPO' P' is situated the melting point curve of//- and 

 w-nitrotoluene. If, however, a small quantity of m-nitrotoluene is 

 present we do not determine a point of the melting poinl curve 

 O'E', P', but a point of a curve situated on a line 0"E',P", which is 

 obtained by carrying through the prism a plane paralell to the OP 

 plane, and this at a distance from the <H' plane corresponding with 



the am t of mela present. If an arbitrary mixture M consisting of 



//-, j>- and ///-nitrotoluene is cooled a separation of solid Ortlw Or para 

 will lake place at a definite temperature; all depends on whether the 

 mixture has the composition indicated by the right or the left melting 



