152 RESEARCHES ON THE VOLATILE HYDROCARBONS. 



mark : " The formation of cumene is easily explained. In effect, the euminic acid 

 being represented by C 40 H24 4 , it appears that C 4 4 , that is to say, 2 equivalents of 

 carbonic acid, are retained by the baryta, while C^ H^, are set free/'* 



Q» H12 2 — C 2 2 -j- Ci 8 H 



12 



14 ) 



In another place (p. 88) they remark, that " by suitably managing the heat, and 

 employing no more than 6 gr. of euminic acid at a time, no other products are ever 

 obtained than those which we mention." f My experiments show that this reaction 

 is by no means so simple as thus described. The crude product obtained from the 

 mixture of lime and euminic acid, when subjected to a simple distillation from a tubu- 

 lated retort, was found to distil between 155° and 250°, leaving a residue at the latter 

 temperature which became semi-fluid on cooling. The distillate thus obtained gave, 

 by my process of fractional condensation, an oil boiling at 151*1, and a residue at 

 170". It is not improbable that the latter may prove to be mostly cymole, C^ H 

 but the quantity was too small to admit of pursuing this inquiry with the probability 

 of deciding the question. There is evidence, however, that the product obtained by 

 Gerhardt and Cahours was not simply pure cumole, as they described it, but a mixture 

 of different bodies, which would necessitate a more complicated reaction than that which 

 they assigned. Gerhardt ami Cahours found the boiling-point of tlieir cumole to be 

 constant at 144°. Four years later, Gerhardt, J having occasion to make a very accu- 

 rate determination of the boiling-point of this body, in connection with his research to 

 find a law governing the boiling-points of the hydrocarbons, found its boiling-point to 

 be 9' higher, viz. 155°, which is but 2° higher than my own determination. The dis- 

 agreement between their determinations, it being so considerable, may be more rea- 

 sonably accounted for on the supposition that they operated, in the first instance, 

 upon a mixture of different bodies; and yet I cannot see how they could have 

 obtained the product boiling below 150°. Additional evidence on this point will be 



in the discrepancy which appears between their determination of the vapor 

 density, and that calculated upon theory. 



The specific gravity of my preparation of cumole was found to be 0.8792 at 0°, and 

 0.8675 at 15\ 



found 



• 



" La formation du cumene s'explique ailment. En effet, Taeide euminique etant represent par 

 U*H 24 4 , on voit que C 4 4 , e'est-a-dire 2 equivalents d'acide carbonique sont retenus par la baryte, tandis 

 que CasIL,, sont degage." — Annales de Chimie et de Physique, 1841, 3 e Serie, L 89. 



t « En dirigeant la chaleur convenablement, et en, n'employant pas plus de 6* r - d'acide euminique a la fofe, 

 on n'obtient jamais d'autre produits que ceux que nous venons de nommer." 



\ Annales de Chimie et de Physique, 1845 (3), XIV. 107. 



