THE ANALYSIS OF TOLUENE AND BENZENE IN 



COAL TAR OILS. 



By George Harker, d.sc, 



Assistant Lecturer and Demonstrator in Organic Chemistry (Pure 

 and Applied) in the University of Sydney. 



[Bead before the Royal Society of N. 8. Wales, June 7, 1916. ,] 



At the outset of certain munition work dealing with 

 toluene, which had been undertaken on behalf of the Federal 

 Munitions Committee, it became necessary to find a reli- 

 able method for the estimation of toluene and incidentally 

 of benzene in coal tar oil. Reference was made to 

 standard works of analysis, and several papers on the sub- 

 ject which had appeared in recent chemical literature 

 were consulted. It was found that while the methods 

 employed were similar in general principle they differed 

 very considerably in detail. In most cases after a pre- 

 liminary distillation of the coal tar oil to a temperature of 

 150° to 170°, followed generally by a purification of the oil 

 so obtained with sulphuric acid and soda, resort is had to 

 a distillation test which varies greatly as given by different 

 authors. In this distillation test, which must be carried 

 out under rigid conditions, the volume of distillate at cer- 

 tain fixed temperatures is noted, and by reference to a table 

 the percentage of toluene is estimated. The range of any 

 of these tables correlating volumes of fractions collected 

 up to and between certain temperatures with benzene and 

 toluene content is more or less limited, e.g., the table may 

 only hold good for samples containing between 50 and 75 

 per cent, of toluene, in which case other samples must be 

 mixed with benzene, toluene, or xylene before distillation.* 

 James on the other hand, 3 employs three preliminary dis- 

 tillations to separate the oil into three fractions, No. 1 



1 H. G. Coldman, Journ. Soc. Chem. Ind., vol. 34, p. 163. * 16., vol. 35, 

 pp. 236 - 240. 



