ee ee 
1885. ] Mineralogy and Petrography. _ 1095 
acquaintance with the general phenomena; it is admitted that 
local elevations occurred, and some of the widely isolated points 
thus elevated are enumerated, and other explanations of the 
phenomena are passed under review, but dismissed as either in- 
sufficient or actually confirmatory of Darwin’s theory. The 
soundings of Mr. Murray off northern Tahita, showing the rapid 
increase of depth beyond the forty fathom line until, at a mile 
from the shore, the slope of the ocean bottom was nearly that of 
the land, are shown to be exactly in accordance with the subsi- 
dence theory. The strongest evidence, derived from the writings 
of A. Agassiz and the soundings of the Blake, points to a great 
subsidence in the Florida region during the coral reef era, and 
the elongation of the coral reefs and formation of inner channels 
now going on by drifting coral sands is shown to be but a part 
of the sand-beach forming process which is in operation along 
the entire Atlantic coast of North America, from Long Island 
southward, and to in no way vitiate the evidence in favor of pre- 
vious subsidence. The abrasion-solution theory of Semper seems 
to be negatived by the absence of open channels in the lagoons of 
the smaller atolls, moreover, instead of small lagoons having 
the purest waters, it is they which are most choked by coral 
sands. Almost perfect skeletons of Rhyttna gigas have been 
recently mounted in the National Museum, Washington, and in 
the British Museum. 
MINERALOGY AND PETROGRAPHY.' 
New Minerats.—Gerhardite— Messrs. Wells and Penfield? 
have described natural crystals of a basic copper nitrate which 
‘was first identified by Professor Brush, of New Haven, on speci- 
mens of copper ore from the United Verde mines, Jerome, Ari- 
zona. The crystals, which belong to the orthorhombic system, 
are mainly made up of a large series of pyramids and the basal 
Pinacoid, Twelve forms were observed. Color dark green; 
hardness 2; specific gravity 3.426. Plane of the optic axes is 
the brachypinacoid; double refraction very strong, negative ; 
pleochroism distinct. 
An analysis gave : 
H,O CuO -o N0; 
11.26 66.38 22.25 
Named after the chemist who first determined the composition 
of the same compound made artificially. This is the only insol- 
uble nitrate known in nature. 
Hanksite—This name was suggested in May of the present 
year, by Mr. W. E. Hidden; for an anhydrous sulphato-carbonate 
1 Edited by Dr. Gro. H. WILLIAMS, of the Johns Hopkins University, Baltimore. 
* American Journal of Science, July, 1885, p. 50. 
*Ib., Aug., 1885, p. 133- 
VOL, XIX—NO. xr, 72 
