230 Dr. Cooper on Voleanoes 
these rocks and the basalt connected with them. Dolomieu 
remarks the same, as to the basalt and greenstone of 
gypt: some very important observations to the same pur- 
pose have lately been made by Dr. M’Culloch in his paper 
on the granite of Aberdeenshire. The vulcanists say, these 
are not different formations, but one connected and con- 
tinued series of ejections, under different degrees of heat 
operating on them; and they apply this reasoning to the 
sienitic granite of Christiana, observe u 
and Haussman : Cellular, or vesicular basalt, often incloses 
in its cells, peridot, carbonat of lime, Zeolytes of various 
kinds, prehnites, green earth, &c. In the large cells of 
Geodes (as at Oberstein) we find Agate, Chalcedony, 
Quartz. The cells are sometimes round, and sometimes 
elongated in one direction 
Until lately, on the suggestion of M. Cordier, the pres- 
ence of Augit has not been particularly noticed in basalts ; 
which are sometimes augitic, and sometimes amphibolic ; 
ie: within my own experience more commonly indetermi- 
. Observers with good eyes anda good microscope, 
bresksg the basalt into minute fragments, but not into dust, 
may often determine this very important point. 
Analysis of basalt. Bergman. Klapr. Kennedy. 
Silex - - 50 - 44 50 - 46 
Alumina - 15 - 16 75 - 16 
Lime - 8 - 9 50 - 4 
Magnesia - 2 . 2 25 ~ 0 
rh of iron - 25 - 20 - 16 
Sod - - 2 60 ~ 4 
Ox. ‘Mitceside - - 12 - 
Mur. acid - - - 5  - i 
Water - - 2 - 5 
$ - - rh ~ eee 3 
100 100 100 
The varieties thus analyzed appear to be of the Fletz 
trap formation. 
