RESEARCHES ON THE VOLATILE HYDROCARBONS. ]H 



remain as to the relations of these bodies to one another, yet their composition hag 

 been ascertained with certainty." It does not appear, however, that an analysis or 

 vapor density of any one of the members of this series, as obtained from coal-tai 



pt benzole, had ever been published. As already indicated by the title of 





paper, it appears to have been the design of Church to treat only of the boiling-points 

 of these bodies ; yet finding that his preparations of toluole — prepared both from 

 coal-naphtha and toluylic acid — gave a boiling-point differing considerably from 

 observations previously published, he took occasion to make analyses of his prepara- 

 tions of this substance, which he regards as "perfectly satisfactory"; and adds that 

 " the details and numerical results of these analyses, and of many others which the 

 present inquiry necessitated, the limits and special object of the present paper do not 

 admit of my giving here." As he undertook to correct the work of his predecessors, 

 to do which fairly would seem to require the publication of these " details and 

 numerical results," their omission is to be regretted, the more since he found space 

 and purpose for matter apparently less relevant to his special subject. I am prompted 

 to these remarks from having been led to undertake the tedious task of making a 

 re-examination of coal-tar naphtha mainly on account of the disagreement between 

 Church's determinations, which I have found to be mostly incorrect, and those which 

 had been previously published. 



In addition to the bodies mentioned in the foregoing table, Church alludes to the 

 discovery of two other bodies, boiling respectively at 97° and 112°. Subsequently, in 

 a "Note on Parabenzole, a new Hydrocarbon from Coal-Naphtha,"* he publishes the 

 details of an investigation of the former of these two bodies, which he finally found 

 to boil "perfectly constant at 97°.5," and to be isomeric with benzole. 



I think I shall be able to show in the following pages, 



1. That coal-tar naphtha contains only four hydrocarbons within the range of 80' 

 to 170°, as taught by Mansfield, and confirmed by Ritthausen. 



2. That the benzole series within that range of temperature is limited to four mem- 

 bers, and therefore does not contain five, as has been generally supposed. 



3. That these four members have the boiling-points 80°, 110°, 140°, and 170° re- 

 spectively ; and consequently that the boiling-point difference in this series, for 

 an elementary difference of C 3 H 2 , is 30°, instead of 22° and a fraction, as alleged 

 by Church. 



4. That the body obtained from coal-tar naphtha, boiling at 140°, is not identical 

 with cumole from cuminic acid, as assumed by Mansfield, nor even isomeric with it ; 



* Philosophical Magazine, 1857, 4th Series, XIII. 415. 



