[92] 
Practical Hints. 
Fixing Indian Ink.—Indian ink is composed of the finest 
ivory black and a gelatine size, and is excellent for plans and 
drawings until any colour, “ wash ”—or even a little dampness— 
comes near the lines, when they then either “blur” or “run” 
together. This may be prevented by dissolving in the water used 
for rubbing up the ink about eight grammes of bichromate of 
potassium, or six and a-half of the corresponding ammonium salt, 
per fluid ounce. 
Razor-Strop Paste.—Emery for preparing razor-paste is better 
obtained by pounding the coarse kind thoroughly in a mortar, and 
throwing it into a large jug of water, and stirring well. Immedi- 
ately the large particles have sunk, pour off into a shallow vessel, 
and let the water evaporate. This emery is better than that 
prepared at the emery mills. (1) Take of this emery, 2 parts ; 
spermaceti, r part; mix together, and rub over the strop. (2) 
Jewellers’ rouge, black lead, and suet, equal parts; mix. (3) 
Levigated oxide of tin (prepared putty powder), 1 ounce; 
powdered oxalic acid, } ounce ; powdered gum, 20 grains ; make 
into a stiff paste with water, and evenly and thinly spread it over 
the strop. With very little friction this paste gives a fine edge to 
the razor, and its efficiency is still further increased by wetting it. 
Silver-plating Fluid.—A new silver-plating fluid of great 
value is thus described in the Polytechnisches Journal :—Dissolve 
500 grains of potassium iodide in 16 ounces of distilled water, 
and to the mixture add 666 grains of silver nitrate, dissolved in a 
similar amount of distilled water. The fluid thus formed is not 
affected by light, will keep indefinitely, and requires a very weak 
amount of electricity for its decomposition. Articles silvered by 
this process should be washed in a solution of potassium iodide, 
in water (1 part of the former to 4 of the latter), before polishing 
or burnishing. 
Nutritive Solution for House Plants.—The following is said 
by the Droguisten Zeitung to be excellent :—x part each of 
potassium carbonate, potassium phosphate, magnesium carbonate, 
and sodium silicate ; 2 parts of potassium nitrate, and 3 parts of 
sulphate of iron, are dissolved in 2000 parts of water. A little of 
the solution is poured around the roots of the plants from time to 
time. This solution, or one very similar, was suggested by Liebig 
many years ago, and is highly prized by those who have used it. 
(Cleaning Brass.—It is a great mistake to clean brass with 
acid. It very soon becomes dull after such treatment. Sweet oil 
