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 touc