Academy of Sciences, Paris. 147 
by gas on the Continent, accompanied by some remarks on the 
lighting of London; with suggestions for the improvement and 
extension of this valuable branch of discovery. ; 
Feb. 4. A paper was read, communicated by the President from 
Mr. William Scoresby jun. on the Anomaly of the Variation, oF 
the Magnetic Needle on board ship. Mr. Scoresbystates, as the re- 
sult of a long series of personal observations, what When the com- 
pass is placed in one particular part of a ship, there is no varia- 
tion, as between north and south; and that when placed in an- 
other position, there is no variation, as hetween east and west. He 
accordingly suggests, that a medium point between these two 
lines may probably be found, where the compass will act free from 
all variation, either as to north or south, or as to east and west. 
A paper by Mr. Bain on the same subject was also read at 
this meeting, showing by a number of examples the great extent 
of the variations of reckoning occasioned by the local attraction 
of ships. 
Feb. 12. A paper was read, communicated by Dr. Leach, from 
Mr. Thomas Say of Philadelphia, containing a scientific descrip- 
tion of a new species of the genus Ocythoe discovered on the 
American coasts. 
ACADEMY OF SCIENCES, PARIS, 
At the sitting of 5th of October last, was read by M. Thenard 
a Series of observations on the Oxygenized Acids and Oxides = 
which, the author observed, embrace facts so singular that they 
will excite some surprise. ‘T hey are as follows : 
“I. The oxygenized nitric and muriatic acids dissolve the hy- 
drate of the deutoxide of mercury without effervescence ; but if 
an excess of alkali be afterwards poured into the solution, a con- 
siderable disengagement of oxygen ensues, and the oxide of mer- 
cury, which at first re-appears of a yellow colour, is quickly re- 
duced. 
‘II. When this hydrate is brought in contact with the oxy- 
genized nitrate or muriate of potash, it is reduced with equal fa- 
cility. It passes from yellow to gray, giving off at the same time 
much oxygen. 
“TIL, Oxide of gold, obtained from the muriate by means of 
barytes, and containing such a small portion of the base as gave 
it a greenish hue, being put, while in a gelatinous state, into oxy- 
genized muriatic acid, a strong effervescence instantly followed, 
occasioned by a disengagement of oxygen. The oxide assumed 
a purple tint, and was, soon after, completely reduced. 
“IV. Oxygenized sulphuric, nitric and phosphoric acids, like 
_  * See M. Thevard’s paper in our Number for January ; also his paper on 
the acids and oxides in the present Number, p. 109. 
K 2 
