_ retical vapor density is below that found by experiment. 
older than the Carboniferous,—not a trace of any Silurian or De- 
264 Scientific Intelligence. 
analyses to settle this question. Then to determine the probable 
formula o y l ely 
elouze and Cahours gave to their body boiling at 216°-218°, 
the formula €,,H, ., the theoretical vapor density of which, by my 
9. 
calculation, is 6°365; their determination of the same was 6°569. 
BS : 
> * 
contain full details 
hydrocarbons that I have separated from Pennsylvania petroleum, 
and I will send the article soon after, for i action in 4 Ameri- 
can Journal of Science. 
He I rl a 
Il. MINERALOGY AND GEOLOGY. 
1. The Carboniferous age of a portion of the Gold-bearing Rocks. 
¥, California ; by Wutiam P, Buaxr.—In a former No. of this’ 
ournal™ Prof. W. H. Brewer, in noticing the reports of the Geo-. 
logical Survey of California, observes as follows: “ We are now led 
naturally to consider the question of the age of the rocks of the 
auriferous series in California. They have been regarded as older . 
statement from Prof. Whitney;+ “We have not a particle of 
eupenos to sustain the theory which has so often been brought 
orward that all, or even a portion, of the auriferous rocks are 
vonian fossil ever oe been discovered in California or indeed 
the west of the 1 meridian,” 
* Volume xii, No. 123, May, 1866 , 
May, , P. 361, a 
+ Report of the Geo! Survey of California, vol. i, Paleontology, Preface. 
