THE YOUNG SCIENTIST. 
147 
ored grouna, use the sealing-wax varnish made 
by dissolving red sealing-wax in spirits of wine. 
Let the whole get thoroughly dry ; and if it is 
not well covered give it another coat. 
When this is dry, let the whole work be 
brushed with a bristle brush dipped in spirits of 
turpentine, and rubbed pretty hard until the 
parts covered with the white mixture are left 
bare. The designs first traced will now become 
visible, with sharp, clear outlines marked on the 
black or red ground, and will look very hand- 
some. It must then be varnished with white 
varnish, and rubbed down with pumice powder 
until very smooth. 
. 
Removal of Iron-stains from Linen.— 
"Salts of tin" are said to be better for this pur- 
pose than oxalic acid. 
Shaping- Soft Rubber with a File.— Prof. 
Morton, of the Stevens Institute, states that he 
finds the ordinary thick sheet rubber, used in 
making 'up lantern tanks, and for many similar 
purposes, may be readily dressed into an exact 
shape with a file, if only it is supported by being 
clamped between plates of wood or metal in a 
vice. The file is used dry, and in all respects as 
in working on wood or metal. 
Green Bronze.— Dissolve 2 oz. of nitrate of iron, 
and 2 oz. of hyposulphite of soda, in l pint of water. 
Immerse the articles in the bronze till of the re- 
quired tint, as almost any shade from brown to 
red can be obtained ; then well wash with water, 
dry. and brush. One part of perchloride of iron, 
and two parts of water mixed together, and the 
brass immersed in the liquid, gives a pale or deep 
olive green, according to the time of immersion. 
If nitric acid is saturated with copper, and the 
brass dipped in the liquid, and then heated, it as- 
sumes a dark green. If well brushed, it may be 
lacquered with pale gold lacquer, or else polished 
with oil. 
Waterproof Dressing- for Leather.— The 
Boston Laboratory gives as a waterproof dressing 
for boots, shoes and leather the following: Lard 
oil, 100 parts ; paraffin, 50 parts ; beeswax, 5 parts. 
Gently warm the oil and in it dissolve the paraffin 
aLd wax. If too hard, use a little less wax. Any 
disagreeable smell may be removed by a few 
drops of oil of sassafras. The wax prevents the 
crystallization of the paraffin, and the oil causes 
the whole to become a paste of the consistency of 
tallow. The dressing fills the pores of the leather, 
does not dry, but keeps the leather soft and pli- 
able. Boots and shoes to which the dressing is 
applied may be polished, using ordinary black- 
ing, which is not the case with most dressings 
containing oil or grease. 
Waterproofing Linen. —Professor Kurr gives 
the following directions for this purpose : Pass the 
linen first through a bath of one part sulphate of 
alumina in ten parts of water, then through a soap 
bath, of which the soap is prepared by boiling one 
part of light-colored resin and one of crystalized 
carbonate of soda with ten parts of water until the 
resin is dissolved. The resin soap thus formed is 
to be separated by the addition of one-third of 
common salt. In the soap bath the resin soap is 
dissolved, together with one part of soda soap, by 
boiling it in thirty parts of water. From this bath 
pass the articles finally through water, then dry, 
and calender. Made-up articles may be brushed 
with the solutions in succession, a,nd be rinsed in 
the rain. Wooden vessels may be employed. 
Working Ash.— Steam is the ordinary means 
used to soften ash, but when it is practicable, 
boiling in water is the best. The chief thing is 
to have the right kind of ash, as some kinds bend 
and others do not. One tract of land may furnish 
the best of ash, while another, lying close by and 
having just as good a soil, may produce only an 
inferior quality. The timber must be heavy and 
tough, and cut from good trunks. No matter if it 
has been cut and dried three years. A splinter of 
this quality of ash can scarcely be torn off, and 
runs the whole length of the wood before it ceases. 
Half an hour's boiling is sufficient to soften a 
piece of wood six centimeters thick. When the 
wood is taken out of the kettle, put it in the brace, 
screw and v/edge it in the desired form without 
relaxing, and let it cool a few hours. After the 
wood is thoroughly dried in the brace, unscrew 
it and take out the wedges ; it will always then 
retain its form. 
EXCHANGES. 
One Bunsen battery, extra zinc pot, chemicals 
and instruction book, cost $3.40, for sleight of hand 
tricks of similar value. Thos. A. Black, Lock 
Box 678, Scranton, Pa. 
Collection sea curiosities and shells, or book. 
Exploits of Paul Jones, for best friendly letter to 
an invalid young man ; no letters answered ex- 
cept prize ones ; scores of curious things from the 
ocean beach at Newport, Oregon, to exchange for 
almost anything of value ; state offers ; some type 
and eyeglasses wanted. Theo. Boone, Oneatta, 
Benton Co., Oregon. 
A card printer with type, pads, ink. blanks, 
tweezers, etc., also 100 best mixed cards, also a 
good dark lantern, also 1876 and 1877 of " Youths' 
Companion," also 1 pair skates, and 1874 of 
"Wood's Mag.," and 1869 of " Peterson's Mag.," 
and other things in exchange for anything of 
equal value. C. T, Conover, Esperance, N. Y. 
Photographer's car, fine, $300 ; landscapes, out- 
side, $60, or case containing collection birds and 
animals worth $1,000: will give minute description 
to persons having offers. R. B. Gronslot, Sand- 
wich, III. 
Tenney's Natural History, and 16 vols. 1850 to 
1865 of Annual Scientific Discoveries, by Wells ; 
cost $24 ; to exchange for fossils, or offer. Hugh 
W. Hanna, Wabash, Ind. 
To exchange, books, amateur papers, type, etc., 
for fossils, rocks, minerals, and Indian relics. C. 
E. Hodge, 151 22d St.. Chicago, 111. 
