The Sun.
London, England, 1858-11-24 00:00:00

FRENCH ACADEMY OF SCIENCES.

At the last sitting M. Pouillet announced that
the committee appointed at the request of the
Minister of Agriculture, Commerce, and Public
Works, to examine certain important questions re-
lating to the laws on weights and measures, has found
it'imposSible to reply to them, without undertaking a
series of experiments which will require much time.
M. Pouillet, therefore, requested the Academy to
inform the Minister of this inevitable delay. M.
Despretz communicated a long account of a series
of experiments he had been carrying on since May,
1857, in order to ascertain whether the chemical
substances hitherto looked upon as elements or
simple bodies were really such or not. Chemists,
accustomed to the almost daily occurrence of the
most unlooked-for and surprising decompositions,
were generally imbued with a kind of scepticisfn
as regarded the undecomposable nature of certain
bodies. , In 1807 Sir Humphrey Davy expressed
an opinion that metals and other simple bodies
were mere compounds of an unknown base and of
a substance forming a constituent of hydrogen ;
Gay-Lussac and Thenard regarded potassium and
sodium as a combir ation of their alkalies with

hydrogen. In 1847, Gerhardt declared that the.
simple nature of the elements was not matheraa-,
tically demonstrated, and that science might some
day succeed in decomposing sulphur, carbon, and
the. metals. In 1857, M. Dumas, in a paper
addressed to the Academy, admitted the existence'
of two conflicting opinions, one regarding the' sub-
stance called elements of simple bodies, the other,
on the contrary, considering them as resulting
from a single. substance ; hydrogen, fcr instance,
condensed to a degree varying according to the
nature of the different substances. The latter hype-
thesis originated with Dr. Prout, who supposes a
metal, for example, to be neither more nor less
than hydrogen, or a still lighter gas, reduced to a
solid state by, condensation. In order to test these
strange opinions, M. Despretz has subjected cop-
per, lead, zinc, &c., to very high temperatures,
and decomposed their salts in various ways, always
obtaining the said metals in their natural state,
whence he concludes that they are real elements,
having different properties, and not produced by
the condensation of any gas. M. Encke sent
in a long communication on the comet 'which
bears his name, with numerous tables tending to
show the diminution of time observable in its
periodical reappearance. Mr. Encke first observed
it in 1819, but M. Gibers. had since shown that it'
had been accidentally observed twice in 1786 by
.MM. Mechain and Messier, and that the eamet of
1795 41.scr was no other than M, nuke's. Taking
all these facts together, and calculating the periods
of reappearance, M. Encke now shows that the
time of the .comet's revolution, which *as 1,212.63
days in 1786-95, has fallen to 1,210.57 days in .
1855-58, being a loss 0f2.06. days in the course .
73 years. This diminution M. Eneke explains by
a new hypothesis,' viz., the resistance of a medium
diffused throughout space. Dr. Bouchet presented,
a statistical table from which he deduces that fr9iT4
1826 to 1840 the deaths by crony wpro
and from 1840 to 1856 they amounted to 5,927;
and that out of 388 operations of tracheotomy
there were only 42 cures, showing a mortality of
90 'per cent, Dr. Dufraysse communicated a case
of aspityot la a nevii7-born infant, the life cif
which he saved by inti3odneirtg a tube into the
larynx after Dr. Bouchet's method,