2 Knecht & HiBBERT, Products isolated from Soot. 



was identified as the heptacosane C07H56 of Schwalb. 

 Although the distillation was done rapidly, some doubt 

 existed as to whether some of the products might have 

 been formed by pyrogenic action (technically known as 

 "cracking "), and for this reason we have now endeavoured 

 to isolate individual products without having recourse to 

 distillation at all, or at least only in one case, where it 

 •did not seem likely to exert a cracking effect. The work 

 proved to be very slow and difficult, and as we do not 

 consider the value of the results attainable to be com- 

 mensurate either from a theoretical or a technical point 

 of view with the time and material which it would be 

 necessary to employ for a more complete research, we 

 liave decided to discontinue our work in this direction. 

 We shall content ourselves, therefore, with recording here 

 the somewhat meagre results which we have obtained. 



The soot employed in the new experiments was 

 household soot from the Warrington district. Mr. John 

 Allan, chemist to Messrs. J. Crosfield & Sons, kindly 

 undertook to extract 10 lbs. of this (very bulky) substance 

 in a small extractor in their technical laboratory. The 

 solvent employed in this very slow process was benzene, 

 which was specially rectified for the purpose. The 

 extract, after being freed from the solvent, amounted to 

 about 2 lbs., and represented a semi-solid, pitchy mass, 

 which softened on being heated, evolving a strong smell 

 of soot. This raw material is referred to below simply as 

 soot tar. 



After having experimented on this soot tar with 

 a great variety of solvents, we were ultimately successful 

 in isolating a definite product from it by adopting the 

 following procedure : — 



The substance was extracted with petroleum ether, 

 and after distilling off the solvent, the resulting yellow 



