ANALYSIS OF TOLUENE 43© BENZENE IN COAL TAR OILS. 



103 



Preliminary 4istillation of 250 c.c. in an ordinary distill- 

 ation flask at 170° O. 



I. II. III. 



Distillation Temp. 



C.C. 



C.C. 



C.C. 



100° 



18 



10 



5 (including 25 c.c. 



130° 



100 



17 



water) 



150° 



135 



40 



6 (including 30 c.c. 

 water) 



170° 



163 



70 



10 



Left after washing 



136 



53 



benzene and toluene 



with cone. H 2 S0 4 







present in very 



and NaOH 







small amounts. 

 Not further exam. 



The next step consists in the distillation of the washed 

 oil from samples I and II in a round bottomed flask pro- 

 vided with still-head, the distillation being carried out as 

 nearly as possible at the rate of one drop per second. After 

 completing the distillation and measuring the residue, the 

 latter is put back into the distillation flask and the esti- 

 mated quantities of pure benzene, toluene, and xylene 

 added. The blank test is then performed. 

 No. I. Sample. 







Blank consisting of 





68 c.c. of washed oil. 



20 c.c. benzene, 22 c.c. 



Remarks, 







toluene, 3 c.c. xylene, 









and 23 c.c. residue. 





73° 



first drop 



80° 





80 



1 c.c. 





The blank would 



85 



3*5 c.c. 



4 c.c. 





90 



12 



14 



have been nearer 



95 



18 



18 





100 



19 



20 



the sample if 20c.c. 



105 



21 



22 





110 



23 



26 



toluene and 5 c.c. 



117 



31 



36 





130 



39 



41 



xylene had been 



140 



44 



44 





Residue 



24 

 68 c.c. 





used. 



