180 Miscellanies. 
6. Heat produced by the compression of gas.—In the June No. of 
the Ann. de Chimie et de Phys. Baron Thénard publishes some ob- 
servations on the light which is emitted from air and from oxygen by 
compression.. Common air, oxygen and chlorine, are the only gases 
which are known to emit light when compressed. Hydrogen, azote 
and carbonic acid, afford no such phenomena. Thénard, presuming 
that this difference might arise from the combustion of the oil or 
grease with which the piston of the compressing machine is impreg- 
nated, performed the experiment so as to avoid this source of error, 
by using a piston of potter’s felt, well moistened with water, after 
having washed the tube well with potash to remove the grease. 
There was then no light, how forcible soever the compression of oxy- 
en gas; but at the same time, if a piece of paper or dry wood, were 
attached to the end of the piston, there was a vivid inflammation in 
the same gas. Chlorine presented the same results. Thus no gas 
becomes luminous by simple compression in the pneumatic fire 
pumps. It was ascertained that a fragment of pine wood would not 
inflame in oxygen gas at the temperature of 350° cent. under atmos 
pheric pressure. It only became of a deep brown color, but it inflam- 
ed at 252° under a pressure of 260 centimetres. 
To determine the temperature to which compression would elevate 
other gases, M. Thénard used fulminating powders which exploded 
at different temperatures. He thus ascertained that a gas compressed 
as strongly as possible by hand in a glass tube, rises much beyond 
205° centigrade (or 401° F.) Powders which decompose at 208° 
cent. explode in azote, hydrogen and carbonic acid by sudden and . 
strong compression.—Jbid. 
7%. The seat of taste.—By covering the tongue with parchmenle 
sometimes in whole, and sometimes in different parts, it has been de- 
termined by two experimenters in Paris, M. M. Guyot and Admy- 
raula, that the end and sides of the tongue, and a small space at the 
root of it, together with a small surface at the anterior and superioF 
part of the roof of the palate, are the only portions of surface in the 
cavity of the mouth and throat, that can distinguish taste or sapidity 
from mere touch. A portion of extract-of aloes, placed on any other 
part, gives no sensation but that of touch, until the saliva carries ® 
solution of the sapid matters to those parts of the cavity.—Ibi . 
8. Currents in the ocean, by Charles Rumker, Esq.—* The we 
ters of the Pacific being supposed higher than those of the Atlantic, I 
expected an easterly current on approaching Cape Horn, but I could 
discover none. Near the northern coasts of the Brazils and G@uien® 
