The Sun.
London, England, 1846-10-03 00:00:00

ACADEMY OF SCIENCES.

SITTING OF SEPT. 21.—A communication was re-
ceived from M. Walchner, an engineer of mines in the
Grand Duchy of Baden, having for title " Observations
on copper and arsenic, proving that these two metals are
to be found everywhere." M. Walchner's facts do not
establish the universal presence of copper and arsenic,
but they have an extensive range. He has found them,
he says, in all the iron mines he has visited, and in the
ferruginated waters of Griesbach, Rippoldsdau, W is-
baden, Ems, Pyrmont, &c. This must not, however,
alarm the drinkers of such waters, for the quantity of
arsenic contained in them is so very small, that it re-
quires the nicest analysis to detect it at all. The re-
sult of M. Walchner's paper is, that copper and arsenic
are also to be found in iron. If he bad merely declared
this in the title of his paper, he would have done well.
Another communication was received from M. Boussin-
gault on the process and character of digestion. Accord-
ing to M. Dumas, digestion consists of two orders of
phenomena; it resupplies the materials of the blood in-
cessantly destroyed by respiration, at the same time that
it restores or adds new principles to the organs. Thus,
therefore, digestion must supply on one hand the respi-
ratory combustion, the source of animal heat, and on
the other effect the assimilation of our food. Of the two
phenomena, M. Boussingault regards the respiration as
the most indispensable, inasmuch as the assimilation of
food would be useless without the addition of the animal
heat. The author proceeds at great length, to detail
the experiments that he has made on albumen, fibrine,
caseum, &c., to establish his opinion, but the thing itself
appears to us to be so self-evident that we cannot under-
stand why so much time should have been bestowed in
the way of exemplification. Theoretical disquisitions of
this kind are very useful when they lead to any result
or to the knowledge of any useful fact, but we would
prefer one practical proposition, by which real advantage
may be derived, to volumes of discussion on the mode of
operation in phenomena, the general nature of which is
already so well known.

A Paperwas read on the means of ascertaining, with
more certainty than hitherto, the action and intensity of
electrical currents. The author, Al. Marie Daay, ap-
pears to have taken great pains to arrive at some useful
knowledge on this subject, and as electricity is now
made an important agent in many of the useful arts, he
is entitled to the thanks of men of science and of the
public at large for the labour that he has bestowed.
M. Arago gave an account to the Academy of some
of the effects of lightning upon electrical telegraphs in
the United States of America, observing that the facts
had been communicated to him by M. Eben Mariam, of
Brookly, and entitled to entire confidence. On the 29th
April of the present year, the lightning fell on the wire
of the electric telegraph at Lancaster, without melting or
breaking it. In the room, however, where the electric
battery, by which the line is worked, is placed, a noise
was heard like that of the discharge of a pistol, and se-
veral sparks were seen. On the 18th of May a telegra-
phic wire was broken by lightning, and several of the
posts supporting the line were split. In this case there
was a report equal to the discharge of two or three
muskets. On June 3 the wire telegraph from Washington
to Baltimore was so broken that the communication be-
tween the towns was suspended for several hours.
On the following day, during another thunder-storm,
the wire was not snapped, but at every stroke of thunder
the hands of the telegraphic instrument moved as if the
battery was at work.
M. Pelouze presented to the Academy, in the name of
M. Barreswill, a paper on the liquid blue obtained by
condensing, by means of frigorific mixture, a compound
of hypoazotic acid and bioxyde acid.
M. Arago addressed some questions to" the members
composing the section of chemistry respecting the new
discovery of means for preparing a fulminating cotton,
more potent than gunpowder, of which so much has been
said iii the journals. M. Sehcenbein, the inventor, as
serts that this cotton, although more powerful than gun-
powder, does not explode with noise, and has the advan-
tage of not soiling the tube through which it is dis-
charged. M. Arago said, before he would give credit to
these assertions, he wished to know what was thought of
them by the gentlemen of the section of chemistry ?
M. Thenard observed, that if the preparation spoken
of has the force of propulsion stated by the inventor,
it is utterly impossible that the discharge can take place
without detonation.

M. Dumas said M. Scheenbein had given him several
samples of his preparation. He bad, said M. Dumas,
succeeded in making from cotton a paper clear and
transparent as glass, and flexible as ordinary paper.
The friction of this paper excites electricity in a very
high degree. When a portion of it is placed in the
dark it becomes luminous, and if it be rubbed against
common paper or cloth it adheres to it with such force
that it cannot be removed. This fact, added M. Dumas,
was beyond contestation, for he had frequently made
the experiment himself, but he knew nothing of the ful-
minating substance spoken of by the journals, and now
alluded to by M. Arago. There might, for aught he
knew to the contrary, be something of the kind, but the
statements which had been made on that subject were
probably much exaggerated.