THE YOUNG 
Chrome Ink. 
The following recipe is said to have been care- 
fully tested and to have given excellent results : 
Twenty-four parts of solid commercial extract 
of logwood, one thousand parts of water, and 
two parts of yellow chromate of potash; or for 
a pint of water (a pound, or seven thousand 
grains), one hundred and sixty-eight grains of 
the logwood, and fourteen grains of the chrom- 
ate. Dissolve the logwood in boiling water, 
niter it, and when cold add the chromate. A 
little carbonate of soda (a few grains) may be 
added to prevent the decomposition, which, 
according to some authorities, is liable to take 
place in the fluid on exposure to the air. No 
gum is to be used, as it is not only unnecessary, 
but injurious. The proportions must be exactly 
followed, especially in regard to the chromate, 
any excess of which is unfavorable to the per- 
fection of the ink. 
This fluid is of a deep blue-black color when 
first used, does not corrode steel pens, adheres 
so firmly to the paper that it may be washed 
with a sponge or left for hours under water 
without being dissolved out, and is not easily 
removed by ordinary chemical agents. It is 
also one of the cheapest inks that can be made. 
Instead of the solid extract of logwood, a sat- 
urated solution of logwood may be used (made 
by boiling the wood in water), but the former, 
which may be bought of any dealer in drugs 
and dyestuffs at about twenty cents a pound, is 
much more convenient. 
A Persistent Blue-Bird. 
Ed. Young Scientist— One day last summer a 
male blue-bird came to my window and de- 
manded admission by knocking against the 
window with his bill, and, as soon as the window 
was opened, he would fly on the sill and warble 
a few notes, and then fly away, this he continued 
for two or three weeks, when he suddenly dis- 
appeared, and we saw nothing of him till two 
or three weeks ago, when lie suddenly a ppeared, 
and since that time has kept up almost a con- 
stant knocking on the windows. I cannot pos- 
sibly imagine what he wants, except to hide 
his nest from the English sparrows, which are 
very numerous here. * 
Alexander G. Gibbs. 
A Powerful Light. 
The Briish Electrical Manufacturing Com- 
pany, at Cleveland, Ohio, has recently manu- 
factured for use in the British navy, an electric 
light, which has been tested and found to have 
a 100,000-candle illuminating power— a power 50 
times greater than the ordinary electric lamp 
SCIENTIST. 67 
for street lighting. This is believed to be the 
largest and most powerful light ever made with 
human hands. It is designed to be used in 
night attacks, and to scrutinize the sea for tor- 
pedoes. A 40-horse power engine is required to 
produce the light. The carbons used are two 
inches and a half thick. The intense heat gener- 
ated between the carbon points is half a million 
degrees, one-ninetieth the estimated heat of the 
sun. It is calculated that with an ordinary re- 
flector a beam of light will be cast so powerful 
that a person 15 miles away can see to read- 
by it. 
Pearls.— Set pearls, which have become dis- 
colored by wear, may often be improved by 
placing in a covered vessel with a mixture of 
whiting, ammonia and water, and permitting 
them to remain a few hours. 
Polishing Powder.— A good powder for clean- 
ing jewelry, silver watch cases, etc., is made by 
mixing about four parts of whiting with one of 
rouge, using with alcohol or water ; this, it will be 
found, is easily brushed out of crevices, engra- 
vings, etc. 
To Solder Tortoise Shell.— Bring the edges 
of the pieces of shell to fit each other, observing 
to give the same inclination of grain to each ; 
then secTire them in a piece of paper, and place 
them in hot irons or pincers ; apply pressure, and 
let them cool. The heat must not be so great as 
to burn the shell ; therefore try it first on a white 
piece of paper. 
Liquid Cement.— Equal parts of compound 
tragacanth powder and powdered gum acacia, 
(gum arable,) moistened, according to require- 
ments at the time, with dilute acetic acid, or, if 
the color will not be of any importance, with 
ordinary vinegar. This cement is recommended 
as superior to any that can be bought ready 
made. 
India Rubber Cement.— A good cement, that 
will render india rubber in any form adherent to 
glass or metal, may be made as follows: Some 
shellac is pulverized, and then softened in ten 
times its weight of strong ammonia, whereby a 
transparent mass is obtained, which becomes 
fluid after keeping some little time, without the 
use of hot water. In three or four weeks the mix- 
ture is perfectly liquid, and, when applied, it 
will bo found to soften the rubber. The rubber 
hardens as soon as the ammonia has evaporated 
again, and thus becomes impervious both to 
gases and to liquids. For cementing the rubber 
sheet, or the material in any shape, to metal, 
glass, and other such surfaces, the cement is- 
strongly recommended. 
