ts of boiling
water, Methyl Violet, 5 B, Hofman's Violet, 3 B, or Gentiana Violet, B.
For reddish violet dissolve in a similar quantity of water Methyl
Violet BR. A small quantity of sugar added to these inks improves their
copying qualities. If the writing when dry retains a bronzy appearance,
more water must be added.

NEW INVISIBLE INK.--C. Wideman communicates a new method of making an
invisible ink to _Die Natur_. To make the writing or drawing appear
which has been made upon paper it is sufficient to dip it in water. On
drying the traces disappear again, and reappear again at each
succeeding immersion. The ink is made by intimately mixing Linseed Oil
one part. Water of Ammonia twenty parts, Water 100 parts. The mixture
must be agitated each time before the pen is dipped into it, as a
little of the oil may separate and float on top, which would, of
course, leave an oily stain upon the paper.

BUCHER'S CARMINE INK.--Pure Carmine, twelve grains, Water of Ammonia
three ounces, dissolve, then add Powdered Gum eighteen grains. One-half
drachm of Powdered Drop Lake may be substituted for the Carmine, where
expense is an object.

BRILLIANT RED INK.--Brazil Wood two ounces, Muriate of Tin one-half
drachm, Gum Arabic one drachm. Boil down in 32 ounces water to
one-half, and strain.

WHITE INK.--Mix pure freshly precipitated Barium Sulphate, or "Flake
White," with Water containing enough Gum Arabic to prevent the
immediate settling of the substance. Starch or Magnesium Carbonate may
be used in a similar way. They must be reduced to palpable powders.

INDELIBLE INK FOR MARKING LINEN.--Add Caustic Alkali to a saturated
solution of Corpous Chloride until no further precipitate forms; allow
the precipitate to settle, draw off the supernatant liquid with a
siphon and dissolve the hydrated copper oxide in the smallest quantity
of Ammonia. It may be mixed with about 6 per cent of Gum Dextrine for
use.

TO WRITE SECRET LETTERS.--Put five cents' worth Citrate of Potassa in
an ounce vial of clear cold water. This forms an invisible fluid. Let
it dissolve and you can use on paper of any color. Use quill pen in
writing. When you wish the writing to become visible hold it to red hot
stove.

BLACK COPYING INK OR WRITING FLUID.--Take two gallons of Rain Water,
and put into it Gum Arabic one-fourth pound, Brown Sugar one pound,
clean Copperas one-fourth pound, Powdered Nutgall three-fourths pound;
mix, and shake occasionally for t