28 
THE YOUNG SCIENTIST. 
it cool. When hard, mark your name through 
the wax with a graver and apply aqua-fortis 
(nitric acid) ; after a few moments, wash off the 
acid thoroughly with water, warm the metal 
enough to melt the wax, and wipe it off with a 
soft rag. The letters will be found etched into 
the steel. 
Transferring- Pictures to Glass.— Coat the 
glass with a varnish of balsam of flrin turpentine, 
then press the engraving on smoothly and evenly, 
being careful to remove all air-bubbles. Let it 
stand for twenty-four hours, then dampen the 
back sufficiently to allow the paper to be rubbed 
off by the forefinger, rubbing it till a mere 
film is left on the glass, then varnish again. 
Cementing- G-lass to Metal.— A great deal of 
difficulty is experienced in cementing metal to 
glass. The Faerher Zeitung says that a mixture 
of two parts finely ground litharge and one part 
white lead, and working it up to a stiff paste with 
three parts boiled oil and one part copal varnish, 
adding more litharge and white lead as required, 
is the best material for joining the two sub- 
stances. 
Phosphorescent Powders.— A powder which 
after being exposed to strong sun-light, con- 
tinues to emit light in the dark and so serves to 
render barometers, compasses, etc., luminous, is 
formed thus: Grind and ignite a mixture of 100 
parts carbonate and phosphate of lime (obtained 
by the ignition of shells, especially Tridama and 
Sepia) with 100 parts quick-lime, 25 parts of cal- 
cined salt, and 25 to 50 per cent of the whole mass 
of sulphur. Then add 6 to 7 per cent, of a color- 
ing matter— a sulphide of calcium, strontium, 
barium, magnesium, aluminum, etc. This pow- 
der is particularly phosphorescent under the in- 
fluence of an electric current. 
To Prevent Rusting".— l. Boiled linseed-oil 
will keep polished tools from rusting if it is al- 
lowed to dry on them. Common sperm oil will 
prevent them from rusting for a short period. A 
coat of copal varnish is frequently applied to 
polished tools exposed to the weather. Woolen 
materials are the best for wrappers for metals. 
2. Iron and steel goods of all descriptions are 
kept free from rust by the following:— Dissolve 
>2 oz. of camphor in 1 lb. of hog's lard, take off the 
scum, and mix as much black lead as will give 
the mixture an iron color. Iron and steel and 
machinery of all kinds, rubbed over with this 
mixture, and left with it on for 24 hours, and 
then rubbed with a linen cloth, will keep clean 
for months. If the machinery is for exportation 
it should be kept thickly coated with this during 
the voyage. 
To Make Badly-fitting Blinds and Doors 
Shut Tig-htly.— When' blinds and doors do not 
close snugly, but leave cracks through which 
drafts enter, the simplest remedy, recommended 
by Mr. Schuetse, building commissioner in Dres- 
den, Germany, is this: Place a strip of putty all 
along the jambs, cover the edge of the blind or 
door with chalk, and shut it. The putty will then 
fill all spaces which would remain open and be 
pressed out where it is not needed,when the excess 
is removed with a knife. The chalk rubbed on 
the edges prevents the adhesion of the putty to 
the blind or door, which can then be opened 
without adhesion, and the putty is left in place, 
where it soon dries and leaves a perfectly fitting 
jamb. Any smart boy can do this. 
EXCHANGES. 
Wanted, a cornet ; must be in excellent order, 
state what is wanted in exchange. James B. 
Athearn, New Bedford, Mass. 
Wanted, Archaeological relics and fossils, for 
butterfiies, beetles, spiders, etc. Correspondence 
invited. A. W. Baily, Box 195, Pottstown, Penn. 
Idaho cabinet minerals, books, revolver, stencil 
outfit, an electrizer, for well-bound books of 
travel, biography, history, science, masonry and 
others of an instructive nature. J. P. Clough, 
Junction P. O., Lemhi Co.. Idaho, 
Telegraph instruments with 400 feet of wire and 
battery, it cost $12 ; will exchange for scroll saw, 
or offers. F. Gushing, Wattsburg, Erie Co., Penn. 
An improved camera lucida for drawing, etc. ; 
also, a printing press, chase x 3K, for offers. 
L. De Veau, 87 E. lOth St., New York. 
What offers for a magnificent black walnut min- 
eral cabinet, 5 ft. x 4 ft., desk form, and double, 
has 4 glass doors, 12 drawers, veneered panels, 
with drop handles, massive carved legs, and is 
lined in blue, cost $80 cash. W. L. Farnum, 
Owosso, Mich. 
Postage stamps, spectograph, drawing cards 
in case, sketch blocks, size 12x20 and 9x12 in., one 
book, "No Alternative," for minerals, coins, 
birds eggs, Indian relics or offers. Frank F. 
Fletcher, St. Johnsbury. Vt. 
To exchange: well-mounted slides of hair and 
fur, for other well-mounted slides of same, lists 
exchanged. Address, W. Hoskins, 208 S. Hal- 
stead St., Chicago, III. 
Bare insects, minerals, and shells, in exchange 
for scientific books. P. W. Lee, 310 Marlborough 
St., Boston, Mass. 
A set of carving tools worth 75c. ; card stamp and 
type worth $3.00. State offers, magic lantern pre- 
ferred. Address Frank H. Libby, Saco, Maine. 
A first class sewing machine will be exchanged 
for books or offers. Address, Lock Box, 22 Scho- 
harie, New York. 
Gaskel's compendium, and Virgil's works trans- 
lated by Dryden. State offers. G. Osgood, Jr., 
Abington, Mass. 
Cocoons of attacus cecropia or mounted speci- 
mens of Lepidoptera to exchange for the follow- 
ing cocoons : "A. Luna. " "'A. Prometheus." " Sat- 
urnia Io,"a "Ceratomia quadricornus." E. Perry, 
50 E. Washington St., Indianapolis, Ind. 
Wanted, in exchange for one vol. of " The Boys 
of New York," or the " Young American," a two 
line card printer with type and everything com- 
plete. Address, W. H. Pretty. Bellville, Ont., 
Canada. 
Wanted, to exchange. Lake Superior copper 
specimens for type. T. J. Prince, Houghton, 
Mich. 
For exchange, a small lathe, (foot power). 2 
sewing machines, l Wheeler & Wilson, l Smger 
medium, in good order, but little used; wanted 
cabinet makers tools, tent, or scroll saw. B. P. 
Wakeman. Southport. Conn. 
