RESEARCHES ON THE VOLATILE HYDROCARBONS. 141 
remain as to the relations of these bodies to one another, yet their composition has 
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-tar,- 
except benzole, had ever been published. As already indicated by the title of his 
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 CO, H,, 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. 
