398 Miscellanies. 
ed with volcanic operations, and changed by volcanic heat, Pyrobiolitic ; 
and tufas containing infusoria he calls Pyrobiolite. When the infusoria 
are of fresh-water origin, the deposit is described as Hydrozoolitic, and 
when marine, Halizoolitic.* It may be doubted whether the science 
stands in need of these terms.—Proceedings of the Berlin Academy, 
April, 1845, 
25. On the Kunker, a Tufaceous Deposit in India; by Capt. New- 
spoLp.—The kunker is a more or less compact tufaceous deposit of car- 
bonate of lime or silica. Capt. Newbold brings evidence to prove that 
they were produced from springs of water, remains of which may in some 
instances be detected. ‘The vast kunker deposits in the plains and val- 
leys of India are sometimes upwards of seventy feet deep, overspreading 
places where they could not have been formed from rivers or rivulets, 
Along the edges of trap dykes mounds of kunker are occasionally ob- 
served, like those around the mouths of kunker-depositing springs. In 
the Kurnool territory, there is a warm spring from which deposits of a 
calcareous mud are forming. But around it and below there is a bed of 
kunker partly siliceous, in some portions of which fresh-water shells— 
Melaniz, some Planorbes, and others, and impressions of leaves, are con- 
tained. The shells afford instructive examples of the various stages of 
fossilization. Some of their coats have been completely converted into 
sparry carbonate of lime; others have been filled and remain as casts 
when the exterior shell is inekon off. Others again are lined with drusy 
-erystals of . quartz; in some, this siliceous crystallization i is just beginning 
to roughen the surface of the interior, and is hardly perceptible without 
the aid of a lens, thus exhibiting interesting examples of the processes 
by which fissures in rocks are lined and filled up with minerals which we 
look in vain for in the enclosing walls. Some of the kunker is so firm 
as to resemble the siliceous tufa deposited by the hot springs of Iceland. 
Capt. Newbold states that the siliceous deposits are apparently of older 
date than the calcareous, and were probably formed when the waters of 
the it Si springs had a somewhat more elevated temperature—Phil. 
26. On some of the Substances which reduce Oxide of Silver and pre- 
cipitate it on Glass in ihe form of a Metallic Mirror ; by Joun Sren- 
noust, Ph. D.—It has long been known that aldehyde, when heated in a 
tube with: ammonio-nitrate of silver, reduces the oxide to the metallic 
state, and forms a brilliant coating on the inner surface of the tube. 
* The above names are derived as follows :—stechiolitic, from oorxe10v, an ele- 
ment ; es drobiolitic, from vag, water, and Biov, life, and Ar1Sos, stone ; pyrobiolitic, 
from mv, fire, and the same as the last; hydrozoolitic, from vdug and (wo, animal ; 
halizoolitic, from aas, the sea, and {wov, animal. 
