Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1881-05-07
POPULAR SCIENCE.

POPULAR SCIENCE.
An OPTICAL EXPERIMENT Many read
ers may know the experiment IN which a
| lighted match or candle being moved about
near the side Of one of the eyes III dark
room, reveals the network of blood vessels
in the retina. 4 curious phenomenon OF
the same order has been lately observed by
| NJ. Charpentier. Looking at a sky UNI
| formly Illuminated with ditfuse white light,
he made the two fingers of his right hand
separate about o. to 0 2m), to pass rap
idly to and fro before his eyes, and in
about half a minute the uniform aspect of
the sky was greatly changed. Ga white
background appeared mosaic composed
| Of hexagons of violet purple color, sep
arated by white lines. Other persons. he
says, have repeated the experiment with
success. He gives reason for thinking that
the hexagonal images correspond to the
cones in the fovea and yellow spot, which
cones, pressed together, form a sort of
hexagonal mosaic The white lines proba.
bly, correspond to filaments charged with
CRYSTALS of pigment, which descend from
the chorodian cells.
CONTINENTS ALWAYS CoNTINENTs.- ro-
lessor James D. Dana of Yale, corrects in
letter to the Nature the wrong statement
OF his position on the question of the per-
manency OF continents, made by Mr.. Wall
ace in his recent work on "Island Life "
After showing where and what he has writ
ten on this subject, Professor Dana adds
The view that the continents have al
ways been continents, which have held
for forty years, is written so plainly in the
geology of North America that | am sure
it would never have been set down among
speculations, even by the most exacting OF
British biologists, had attention been fairly
gwen to American facts. If the truth is
not taught by British rocks, it is because
these represent only narrow margin of a
continent, and hence could not be expected
to illustrate general continental develop
ment, hardly more than an animals leg,
however profoundly studied, TIE embryo
logical laws OF the species.
DIsINFEcTANTs- Professor Beilstein, who
has recently studied the various sub
stances used for distinction, arrives in a
communication made to the st. Petersburg
Technical Society, at the following conclu
sions sulphuric acid would be the best
disinfectant if it did not destroy the sides of
the tanks; the use of lime and of salts of
lime ought TO be completely renounced, as
they but temporarily destroy bacteria, and
under some circumstances may contribute
to their development nor does sulphate
of iron, even in a solution of Is per cent.
ultimately destroy bacteria, as they revive
when put into q convenient medium.
Therefore Professor Beilstein recommends
sui phate of aluminium, which is used in
paper and printed cotton manufactures.
The best means for providing 1t is to make
mixture Of red clay with per cent. Of
sulphuric acid, and to. add to this mixture
some carbolic acid for destroying the smell
of the matter which is to be disinfected.
CoPYING DRAWINGS BY method pa
tented by NJ. Joltrain of Paris, it is
claimed that copies OF drawings having
nearly black strokes on white ground can
be made by the following sensitizing mix
ture: Gum, 25 grammes; chloride of So
dunn, 8 grammes; perchloride OF iron at
45 deg B., 10 cubic centimeters; sulphate
of peroxide Of iron, 5 grammes; tartaric
acid, 4 grammes; water to fill up to 100
cubic centimeters. The developing bath
may be solution of feroccyanide of potas-
STUN, red or yellow, acid or alkaline. The
printing is done in the ordinary way, and
the developing in bath of red or yellow
prussiate of potash. After washing the
proof is put into an acidulated bath, which
darkens the lines to an indigo tint, and is
again washed and dried.
SUPPLY OF Coal IN ENGLAND The
representations published some years ago
with regard to the exhaustion Of the Eng
lish codifields by the rapid increase in the
rate of consumption have not apparently
been verified. On the contrary, the econ.
omies effected, chiefly in connection with
the iron trade, have had the result of
keeping the annual consumption at fixed
figure-if anything it has declined. Since
1871, the annual saving of coal in making
pig iron, has amounted to nearly 5000, 600
tons, and as similar reductions have been
made in the steel and other trades, it is
claimed that there is, even now, In spite Of
the strikes, surplus OF coal at bank.
THE CoLDEsr KNOWN SroT Up to the
present time Yakutsk, in Northeast ST.
IBERIA, has oftes been cited as the place of
our earth where the winter is coolest,
while the minima observed during Arctic
expeditions are believed to be the lowest
known. A correspondent of Nature
disputes this, and claims that to Werk-
hojansk, In Northeast Siberia, in longitude
l34' east from Greenwich, and latitude
67i north, belongs that honor. The
lowest winter recorded at Yakutsk is II 3
Fahr. below zero, and at Werkhojausk,
81 q below zero