188 R. Pumpelly—The Paragenesis of Copper 
face oil.” Most of the petroleum, as now obtained from wells in 
apap Shoes yields by the first distillation, either by steam- 
heat or otherwise, about fifteen per cent of nen naphtha, such 
as is miaseiolse called gasolene, benzine, &c., which is entirely 
free from any greasy or oily constituent ; ae this light naphtha, 
by distillation at comparatively low temperatures as describ 
above, yields about ten per cent of its volume of heavy parafiine 
oil, a new substance produced by heating the vapors sas the 
boiling points of the naphtha, and not simply an educt. 
Art. XXVIL—The Paragenesis and Derivation of Copper and 
its associates on Lake Superior ; by RAPHAEL PUMPELLY. 
BELIEVING that we can arrive at a knowledge of the laws 
1 rough @ 
IL The e paragenesis, etc., of the mineral associates of coppel 
tL Conclusions from the facts observed. 
The second part is the result of a careful study of several 
thousand specimens. No series was admitted to the list whet 
there was any doubt as to the succession, except where 
doubt is indicated by an interrogation point. 
I. Lithology of the Trappean Series. 
In the immediate neighborhood of Portage Lake, the a 
com the “Mineral Range” have a uniform trend of J 
e eas rm : 
ie and aay vertical ie of demarkation betwee! — 
the nes y inclined cupriferous series of rocks and the sand- 
