Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1875-09-02
MECHANICAL AND SCIENTIFIC.

WI
The best and most durable insulation
for electric wires is TO thin them and COW
cr with pure rubber.-Sctenttfc american.
"A Frcnchman named Georges has
been for many years experimenting on me
preservation of fish. At length he has in
lv what is desired. Various kinds Of fish
we're placed in bath OF the solution for
two hours then put in cellar, and after
six DAYS were found in state of perfect
preservation Both flavor and color were
perfect. This invention is believed to be
of great value.
The following is o simple mode Of
rendering water almost as cold as ice
without the use of ice: Let the jar, pitch
er or vessel used for water be surrounded
with one or more folds Of coarse cotton
kept constantly wet. The evaporation Of
the water will carry off the heat from the
inside and reduce it to freezing point
In India and other tropical regions where
ice cannot be produced this method OF
proceeding is common.
M. Malassez has contrived an in
strument which is said to be superior to
those previously used for ascertaining the
number of red corpuscles in given
amount of blood It consists of capillary
tube, into which artificial serum is in
. troduced, and which is graduated so
that the contents of a given length are
known. The mean number of red cor
pusclcs in human blood IS discovered
TO be 1000, 900 in each cubic milimctrc
A greater number is found in smaller ar
tefies, and most in the veins that have lost
part of their serum by exosmose. They
are fewer in cases of cancer and tubeGu-
lose. Lead poisoning also lessons their
number.
According to M. Sonstadt, the sea
water Of the British coasts contains in So
luton, besides silver, an appreciate
quantity Of estimated at about one
grain to ton of water This is scparable
by the addition of chloride Of barium, APP
parcntly as an aurate of baryta adhering
to the precipitated sulphatc, which yields,
by assay, an alloy of about six parts Of
gold 10 four of copper. Other methods
have also been devised by chemical inge-
nuity for separating the metals in question
from their solution in sea water, but not,
of course, in manner or to an extent
rendering il practical object. The agent
which keeps the gold of the sea in a sol.
ublc and oxidized condition is, according
to M. Sonsiadt, simply the iodine liber-
atcd under certain conditions.
That glass is practically non con.
Iuctor of heat as well rs Of electricity has
been demonstrated by various ingenious
experiments. A familiar example in
foint is the use of glass as an insulator, a
non conductor for Geographic purposes.
1t is difficult to draw the line of non-con-
duction, but had conductors of heat are
practically assumed AS non conductors.
The question of conduction is simply one
of degree. Thus, let two rods of equal
size and lcngth-but one of copper and
the other of glass-be brought together,
and have ut their extremity u small weight
or marble attached by wax; then apply IA
spirit lamp to their ends touching each
other 50 that the hea, be equally applied
Now, in the copper, owing to its being "A
good conductor, the wax will rapidly
melt and let the weight drop; while in
the case Of the glass, owing to its being 3
very bad conductor, \ long time must
eapse before such n result can cnsuc.
The fact that timed surfaces often
contain lead rs an adulteration in sutii-
ccnt quantities to act injuriously upon
acid solutions OF vegetables. fruit, etc,
which are brought IN contact with them
is well known, and certain wise counselors
do not hesitate TO protest agans, the gen
eral use of these canned fruits, which are
put up in tin instead of glass cans. Since,
however. nothing less than an astounding
Wholesale catastrophe is likely to induce
apublc abandonment of this class of lux
urics. il may be OF service 10 name sim
pie method by which the presence of acid
can be detected, and thus the manufactures
he compelled to furnish u purcr material.
Having cleaned the suspected surface
thoroughly place upon it a drop or thin
coating ofntric acid, Through the chem.
ical reaction thus induced stannic oxide
is formed and nitrate of lead, If this metal
be present After few moments the acid
should be expelled by means OF gentle
heating, the pulyerulent spot produced by
the acid should then be treated with So
luton composed of five parts of iodide OF
potassium in 100 parts OF water, Should
lead hc present this treatment will result
in the formation of yellow iodidc of lead
which may he readily detected by its char
actcriS'ic color, since the iodidc has no ac-
ton upon The pure oxide OF n.-Er-
change