* 
520 Scientific Intelligence. 
mined the specific gravity at 2°79. The rock is very compact and 
I awa; 
takes a high polish, and will doubtless prove to be a valuable 
material for ornamental architecture. 
e deep 
chians has caused the covering of most of these mountain slopes 
d 
crops; and the dimensions of the bodies of unakyte are therefore 
as yet unknown. Apparently forming part of the same series, 
there are heavy beds of specular iron-ore; and the whole series is 
referred with little doubt to the Archean age. 
nalysis of “ Novaculite,” or “ Ouachita Whetstone,” from 
Hot Springs, Arkansas ; by Mr. C. E. Warr.—A ve ure, 
snowy-white specimen of this beautiful material, which has been 
7 ; “ce S e 
fairly described by Dr. D. D. Owen in his ond Geological 
Report on the State of Arkansas,” as “equal in whiteness, close- 
ness of texture, and subdued waxy luster, to the most compac 
forms and white varieties of Carrara marble,” of sp. gr. 2°649, 
proved to consist of : Silica 99°635 (by diff. ), alumina0-1 13, magnesia 
0-087, sodium oxide 07165, potassium oxide, trace; iron, trace 
0 ; i 
thirty minutes’ boiling only led to 3:56 per cent bein taken up. 
—From Notes of work by Students of Practical Chemistry, in the 
Laboratory of the University of Virginia, Chemical News, 
Nov. 29, 1873. 
13. Note on Pickeringite from Missouri, (in a letter to one of 
the editors, from G. C. BroapuxEap, State Geologist of Missouri, 
dated St. Louis, Mo., March 3, 1874.)—The Pickeringite occurs in 
efflorescences on sandstone of the Lower Coal-measures in Barton 
County, Mo. An analysis by the chemist of the Geological Sur- 
h : 
ve hauvenet, gives the following for its composition: 
Sulphuric acid 33-77, alumina 16°58 magnesia 2°92, water 44°64—= 
99°91. This nearly corresponds with the composition given for 
and Harbour’s, Bell’s, Hayden’s, Brandegee’s, Porter’s, Coulter's, 
te.; but omits Dr. Vasey, whose collection was among the largest 
