REMOVAL OF INK FROM HECTOGRAPH.--It is recommended in Südd. Ap. Ztg.
to pour crude hydrochloric acid upon the hectograph, rub with a wad of
cotton, then wash off by holding under cold running water and drying
with a cloth. The hectograph may be used again immediately.
TO CLEAN WALL PAPER.--Four ounces of pumice stone in fine powder are
thoroughly mixed with 1 quart of flour and the mass is kneaded with
water enough to form a thick dough. This dough is formed into rolls
about 2 inches in diameter and 6 or 8 inches long; each one is sewed
up in a piece of cotton cloth and then boiled in water for from 40 to
50 minutes--long enough to render the dough firm. After cooling and
allowing the rolls to stand for several hours, the outer portion is
peeled off and they are then ready for use, the paper being rubbed
with them as in the bread process.--Druggist's Circular.
INSULATING COMPOUND.--Prof. Fessenden recommends for armature work a
compound made by boiling pure linseed oil at about 200 degrees with
1/2 per cent. of borate of manganese, the boiling being continued for
several hours, or until the oil begins to thicken. An advantage of
this borated oil is that it always retains a slight stickiness, and so
gives a good joint when wrapped around wires, etc. Many substances so
used are not sticky and let moisture in through the joints. Where a
smooth surface is required, it is readily obtained by dusting on a
little talc. It can also be given a coat of japan on the
outside.--American Electrician.
HOW TO CLEAN DIATOMS.--As a general rule, we may say that every
specimen of diatomaceous earth or rock needs a special treatment. The
following, however, may serve as a basic treatment, from which such
departure may be taken in each case as the nature of the specimen
would indicate: Boil the material in hydrochloric acid, in a test
tube, from two to five minutes. Let settle, pour off the hydrochloric
acid, substitute nitric acid in its place, and boil again for two or
three minutes. Pour into a beaker of water, stir a moment with a glass
rod and let settle. After the material has fallen to the bottom,
decant the liquid, and fill with fresh water. Repeat the operation
until the water no longer shows an acid reaction. A portion of the
deposit may now be examined, and if not clean, boil the deposit with
tincture of soap and water in equal parts, decant, wash, first with
water, then with stronger ammonia water, and finally, with distilled
water. This usually leaves the frustules bright and sharp.--National
Druggist.
RED INDELIBLE INK.--It is said that by proceeding according to the
following formula, an intense purple red color may be produced on
fabrics, which is indelible in the customary sense of the word.
No. 1.
Sodium carbonate 3 drs.
Gum arabic 3 "
Water 12 "
No. 2.
Platinic chloride 1 dr.
Distilled water 2 oz.
No. 3.
Stannous chloride 1 dr.
Distilled water 4 "
Moisten the place to be written upon with No. 1 and rub a warm iron
over it until dry; then write with No. 2, and, when dry, moisten with
No. 3. An intense and beautiful purple-red color is produced in this
way. The following simpler and less expensive method of obtaining an
indelible red mark on linen has been proposed by Wegler: Dilute egg
albumen with an equal weight of water, rapidly stir with a glass rod
until it foams, and then filter through linen. Mix the filtrate with a
sufficient quantity of finely levigated vermilion until a rather thick
liquid is obtained. Write with a quill, or gold pen, and then touch
the reverse side of the fabric with a hot iron, coagulating the
albumen. It is claimed that marks so made are affected by neither
soaps, acids nor alkalies. This ink, or rather paint, is said to keep
moderately well in securely stoppered bottles, but we should not rely
on it as a "stock" article. A white paint for marking dark colored
articles might be made by substituting zinc white for the red pigment
in the foregoing formula.--Druggist's Circular.
BROWN OR BLACK DISCOLORATION OF SILVERED MIRRORS.--Generally these
spots are due to faulty manipulation, too great dilution of the silver
solution, or touching the plates with the fingers after they have been
cleaned. Sometimes, however, they are due to chemical defects in the
glass itself. In these cases, as a general thing, the discolorations
occur only after several days--a faultless mirror having been made at
first, and the browning subsequently developing slowly. The writer was
a student in the laboratory of Baron Liebig during the time that
distinguished chemist was carrying out the series of experiments which
resulted in devising a method of making silver mirrors commercially.
One of the greatest troubles with which he had to contend was this
browning--the cause for which was never fully cleared up by him. Some
years ago, the writer, having in his possession two mirrors made by
Liebig, and which had gradually become brown throughout, undertook an
examination of the deposit (which had been thoroughly protected from
extraneous influences by a strong film of varnish), and was surprised
to find that it consisted of a layer of silver sulphide. Without going
into detail, the source of the change was later found to lie within
the glass itself. In making glass to be used for mirrors, a
considerable portion of sodium sulphate is used, and in annealing,
this is partly reduced to sodium sulphide, which effloresces on the
surface of the glass. This efflorescence is, of course, removed on
cleaning the glass before silvering; but it is found that, in many
instances, on exposure of the mirror to the light for some time, a
further efflorescence occurs, and it is this which produces the
discoloration in cases such as we have cited. It has been suggested
that the tendency to subsequent efflorescence may be corrected by
boiling the plates, intended for silvering, for a couple of minutes,
in a 10 per cent. solution of sodium carbonate or bicarbonate. We have
no experience with the process, however.--National Druggist.
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