284 
POPULAR SCIENCE REVIEW. 
or Grove’s battery through a solution of terchloride of antimony, 
by means of an anode of antimony and a cathode of platinum, a bright 
black amorphous metallic coating is deposited on the cathode ; and if 
this deposit be scratched by a needle, it rises several hundred degrees 
(Fahrenheit) in temperature, sometimes with an explosion, and gives off a 
small quantity of acid fumes. The same phenomenon, but in a lesser 
degree, occurs when either the teriodide or terbromide is employed. But 
if the fluoride be used, the metallic coating is devoid of the heating pro- 
perty. The inner and outer strata of the deposit are in unequal degrees of 
cohesion. The cause of this very peculiar phenomenon still requires some 
explanation. 
Laplace's Correction for the Velocity of Sound . — The accuracy of 
Laplace’s discovery is supposed by Professor Tyndall to have been rather 
the result of accident than of proper and legitimate calculation. It 
depends upon a peculiarity of air unproved in his day, but which distin- 
guishes it from most other elastic fluids. From Professor Tyndall’s own 
researches he is led to conclude that air possesses no sensible power of 
absorption or radiation. But though air is neutral, other gases, as 
ammonia and olefiant gas, are capable of absorbing from eighty to ninety 
per cent, of the entire radiation from an obscure source, and they possess 
a proportionate absorptive power. From this and other conditions it 
follows that, “ from the moment any molecule receives by the act of con- 
densation an accession to its calorific motion, that motion is in part 
wasted upon the aether in which the molecule swings.” Hence the con- 
clusion, that the correction of Laplace is no longer applicable under such 
circumstances. The writer remarks, “ Apart from other important 
consequences, it would certainly be an interesting and beautiful result, if, 
from a thing apparently so remote as the velocity of sound, we could deduce, 
d priori , the fact which has been now illustrated by nearly five years’ 
experiments — that the elementary gases have no sensible radiative power, 
while the compound gases are endowed with this power in very different 
degrees.” — philosophical Magazine ,” November. 
Change of Form in heated Wrought Iron when cooled in Water. — In a 
paper read before the Royal Society, by Lieut.-Colonel Clerk, some very 
interesting results are recorded. It is found that when an iron cylinder heated 
red-hot is plunged to half its depth in cold water, a peculiar contraction or 
constriction takes place, according to the thickness of the metal, either at 
the water level, or at a point about an inch above it. The constriction is sup- 
posed to result from the opposite motions of two portions of the cylinder, 
the under part tending to pull in the upper, and the upper to pull out the 
under. The under, contracting more powerfully, has the advantage, and 
so, pulling in a part of the upper, produces the peculiar contraction. 
ZOOLOGY AND COMPARATIVE ANATOMY. 
Reproductive Phenomena of Amoebae. — In reply to Mr. Carter’s last 
communication on this subject we have another paper from Dr. Wallich. 
He expresses his opinion that the so-called reproductive bodies described 
