466 Screntific Intelligence. 
series of thermal phenomena connected with the great volcanic 
upheavals and eruptions since the beginning of the Tertiary age.” 
The heated moisture of the Comstock lode is heated by coming 
in contact with hot rocks at a lower level than the present work- 
ings, and the hot sources thus opened are doing to-day what they 
have been doing in the past, though less actively—bringing toward 
the surface the materials taken into solution in a more highly 
heated zone below. Hot, not cold, waters are doing and have 
done the chief part of the ‘work in the formation of mineral veins. 
5. Some placeaigape of Atmospheric action on raaereseie by M. 
E. Wapsworrn. (Proc. Boston Soc. Nat. Hist., vol. xxii, Feb. 7, 
1883. ine. object of this brief paper is simply to aaa on record 
some observations made a number of years ago, and to call the 
attention of others to the subject, in the desire that similar facts 
from field observations, Sea upon sandstone and quartzites. 
As examples of the power of the ordinary atmospheric agencies 
over rocks Iw ould cite some cases observed by me in 1 1871, 72 
posed portions of the same blocks and slabs were greatly indu- 
rated, the grains almost obliterated, and the rock possessed the 
conchoidal fracture and other characteristics of a quartz 
e Potsdam sandstone east of the town likewise possaened 
similar characteristics. In this, concretions of an indurated char- 
ules, and a few Ssidlien farther of the ss auch was incoherent, 
“enaily. crumbling under the touch and showing no trace of con- 
cretionary structure. At an nother grat the oo showed 
in cavities formed by weathering a distinct lining of quartz 
crystals, while a few inches beneath the surface the rock had the 
i) 
consolidated the sands “ibe Se ee not as a seen extensively 
in that vicinity aig the surface rock left by denudation. In the 
autumn of 1872 lock of clear white Potsdam sandstone was 
found on the aoe of a hill, the protected side of which was friable, 
while the other sides, especially the one most exposed to the pre- 
vailing storms, was nearly a quartzite. This block was only 
about two feet square, ead as a test of the correctness of the 
above Senalieton the indurated surface was broken off, and a 
