134 J. D. Dana— Volcanic Glass of Kilauea. 
coal-field. The newer conditions were unfavorable to animal 
life. Marine conditions, however, did not cease with the Fort 
Pierre. The sandstones of the Laramie are of marine origin, 
though perhaps only off-shore deposits. Halymenites major 
occurs profusely in the lowest sandstone wcithif the Trinidad 
field as well as at much higher horizons in the Cafion City 
field. Huge knotted fucoids were found in a sandstone above 
coal bed J, in the former field. Other sandstones, showing no 
fucoids, contain man y battered logs. Limestones, unmistakabl y 
of marine origin, occur up near to the middle of the Laramie. 
The change is not unlike that shown in the passage from the 
Lower to the Upper Carboniferous in the Appalachian coal-field. 
Art. XXII.— On some points in Lithology ; by JAMES D. Dana. 
II. On THE a OF THE CAPILLARY VOLCANIC GLASS OF 
Kinavea, Hawan, CALLED sH 
THE ya ia ‘plese glass of Kilauea collected by the 
writer at the volcano in the year 1840 was analyzed for the 
writer’s Geological Report of the Exploring prea (1849) 
by Prof. B. Silliman (B. Silliman, Jr.), and the results are pub- 
lished in it on page 200. The large Rare between the 
two analyses there reported—one of a dark and the other of a 
pale variety—and especially the difference as to soda, one being 
stated to contain 21°62 per cent, and the other none, left the 
question of composition in great doubt.* I have now to report 
two new satisfactory analyses of the glass. For these, science 
is indebted to Mr. F. J. Allen of the Sheffield Scientific School 
of Yale College, excepting the determination of the state of 
oxidation of the iron, which is by Prof. O. D. Allen. The 
results were as follows: 
i I. Mean. 
Silica .._. 50°76 50°74 50°75 
Alumina 16°68 16°39 16°54 
Iron sesquioxide -...-.... 2°15 2°05 2°10 
Iron protoxide..._...-.... 7°90 7°87 7°88 
Manganese protoxide aoe trace trace — trace 
PRUE ga ances 7°65 7°65 7°65 
BO oon ec ee 11°95 11°97 11°96 
Soda 2°11 2°16 13 
Potash 0°55 0°57 0°56 
My | Fe Ss Bae 0°35 0°35 0°35 
100°10 99°75 99°92 
* The analyses also of volcanic scoria and lava, given on the same page of m 
Report, are evidently too auedetelac $s be hinge quote; Saleay ies results a2all De 
confirmed by other analysts. 
