Juniata sentinel. [volume] (Mifflintown, Pa.) 1846-1873, 1873-09-03
Scientific.

BLACK NARNISH FOR LlNC. = Diach
paint or varnish may be prepared with
the following simple ingredients: Equal
parts of cblorate of potash and blue
yitriol are dissolved in &c times as much
warm water, and the solution left to
cool. If the sulphate of copper used
contains iron, it is precipitated as
hydrated oxide and can be removed 10y
decantation or filtration. The zinc
castings are then immersed for few
seconds in the solution until quite
black, rinsed off with water, and dried.
Even before it is dry, the black coating
adheres to the object so that it may be
wiped dry with cloth. A more econo-
mical method, since & much smaller
quantity of the salt solution is required,
is to apply it repeatedly with sponge.
If copper colored spots appear during
the operation, the solution is applied to
them a second time, and after while
they turn black. As soon as the object
becomes equally black all over, it is
washed with water and dried. On rub
bing, the coating acquires a glittering
appearance like indigo, which disap-
pears on applying few drops of linseed
oil varnish or "wax milk, and the zinc
then has a deep black color and gloss.
The wax milk just mentioned is pre-
pared by boiling | part of yellow soap
and parts Japanese wax in 81 parts of
water, until the soap dissolves. When
cold, it has the consistency of salve, and
will keep in closed vessels as long as
desired. 1t can be used for polishing
carved wood work and for waxing ball
room floors, as it is cheaper than the
solution of wax in turpentine, and does
not stick or smell so disagreeable as the
latter. 4 permanent black ink for zinc
labels is prepared by dissolving equal
parts of chlorate of potash and sulphate
of copper in Is parts of water, and add
ing some gum arabic solution. The
black polish above described is recon-
mended as permanent and capable OF
resisting quite high temperature
Scientific american.
II the discovery that the Lakes Tan
vanyika and Albert Nyanza are one and
the same body of water-a magnificent
inland sea seven hundred miles long
be verified, it will have an important
bearing upon the civilization of Africa.
From the Mediterranean to the equator,
and from the Great Desert to the ocean,
the land is now claimed by the conquest
of Sir Samuel Baker as part of Egypt.
To hold it, access must be gained. AL
ready the Khedive is building a railroad
up the Nile. But, in the belief of Sir
Samuel Baker, long expressed, there is
a better gateway into these far regions
than by rail. 1t is the Nile. He has
brought back information that the river
above the falls" is navigable to Ujiji.
There are many falls in the Nile, be-
ginning at the first and second catar-
acts in Nubia, so that until we get more
accurate information it is impossible to
tell to what extent the river is open. If,
as is probable, Sir Samuel Baker has
found his idea of water navigation from
the Mediterranean, at least at certain
seasons of the year, feasible on the
of certain engineering diff
entities at the falls, it is the most prac-
teal discovery that has yet been made
in Africa.
ORIGIN OF PLAQUES DIR. Tholozan,
physician in chief to the Shah of Persia
recently read psper before the French
Academy of Sciences on the origin of
pestilence. 1t has been generally be-
Iieved, he said, that the plague or erup-
tive fever was exclusively engendered
in low, warm, and marshy regions. es-
pecially in the north of Africa and in
Asia Minor. This opinion is, however,
without foundation, and large number
Of facts as well as the evidence of past
prove that the disease may
originate IN any latitude, under all eli
mates and in all countries, however che
vated. 1t is not consequence of eli
mate or meteOrologic influence, nor even
the necessary concomitant of unhygi-
enic causes, however energetic. Famine,
for instance, breeds typhus fever rather
than the plague. This exclusion of all
physical origin leads to the conviction
hat the malady is due to some animal
the pest, in short, is an or
yauic fermentation.
VI. Tholozan added that he considered
he deadly forms of pestilence so COM
non in Kurdistan to be principally due
o the intimate contact of the inhabi-
ants with their sheen in unhealthy and
BADLY aired cabins.