40 THE YOUNG 
Boil, with stirring, for five minutes, or until the 
licLuid becomes clear, and when cold stir in well 
375 grains of alcohol and five or six drops of pure 
carbolic acid. Keep in well-closed vessels, and 
before using it work up a portion with a brush in 
a dish. 
Lark Food.— The following mixture forms a 
-very excellent food for soft billed birds, such as 
larks: Hemp seed, 3 parts; Zwieback (toasted 
wheat bread) 2 parts ; Maw-seed, 1 part ; Ox-heart, 
1 part. 
Boil the ox-heart well in water, then cut it small, 
and dry it in an oven till perfectly crisp. All the 
ingredients must then be thoroughly mixed and 
ground to a course powder in a mill. This is sold 
by dealers, as food for mocking birds, larks, and 
others. 
For Painting, Graining and Varnishing 
Pine Wood.— Boil 1 lb. of logwood in two quarts 
of water two hours, brush this decoction well 
over the box— this is mahogany color. Kosewood 
serve the same way, but next well streak the sur- 
face, to imitate the grain of rosewood, with the 
following mixture: K oz. green copperas in 
water; apply with a hard brush or fine comb; 
when dry, paper gently to avoid rubbing out the 
color, then varnish it with brown hard varnish, 
using a camel hair brush. If care be taken and 
neatly done, it will have a good effect. 
To Remove Nitrate of Silver Stains.— Dr. 
Kraetzer, of Leipzig, proposes, as a substitute for 
potassium cyanide in removing stains made by 
nitrate of silver, the following: Ammonium 
chloride, 10 grams ; corrosive sublimate, 10 grams ; 
distilled water, 100 grams. Preserve in a glass- 
stoppered bottle. He says that with this solution 
the black stains may be removed from linen, 
cotton, and woolen goods, without injury of the 
fabric. It will also remove these stains from the 
skin, but although it is less poisonous than the 
cyanide, it is a corrosive poison. 
The Metric System in Coins.— It may not be 
generally known that we have, in the nickel five- 
cent piece of our coinage, a key to the tables of 
the linear measures and weights of the metric 
system. The diameter of this coin is 2 centi- 
metres, and its weight is 5 grams. Five of them 
placed in a row will, of course, give the length of 
the decimetre; and two of them will weigh a 
dekagram. As the litre is a cubic decimetre, the 
key to the measure of length is also the key to 
measures of capacity. Any person, therefore, 
who is fortunate enough to own a five-cent nickel 
may be said to carry in his pocket the entire 
metric system of weights and measures. 
Magic Polishing Cloths.— For some time 
past there have been sold in Europe, as polishing 
cloths, square pieces of calico, with which me- 
tallic articles could be polished and cleaned 
without the intervention of other substances. 
They were simply impregnated with a mixture of 
soap and tripoli, and tinted with coralline or 
rouge. For a piece of fabric 30 inches long and 4 
SCIENTIST. 
inches wide, the following quantities are suf- 
ficient: Tripoli, 2 grams (SOgrs.); castile soap, 
4 grams (60 grs.) ; water, 20 grams (300 grs.) The i 
soap is dissolved in the water, the tripoli added, [i 
and a little solution of coralline added to impart 
a rose color. The fabric is then thoroughly im- 
pregnated with the mixture and dried. 
Lnbricators.— The efficiency of lathes, scroll i 
saws, sewing machines, and even watches, often I 
depends upon the judgment and care used in se- ! 
lecting a lubricator, and this choice is frequently 
ill made. Common kerosene oil is too often in- 
judiciously used in place of a thicker or more 
bland oil, because the heat produced by friction 
rapidly vaporizes the oil and leaves the journal 
dry. Crude petroleum for the same reason is 
fitted only for very slowly-revolving journals, 
such as water wheels. For very heavy machinery, 
or for gearing, tallow and black lead rubbed up 
together is the best lubricant, and is also the best 
for wagon and carriage axles during the hot 
weather. For light-running machinery sperm 
oil is the best ; good olive oil that has not become 
rancid and acid, is perhaps the second best, and 
for winter use lard oil is excellent, but is rather 
too drying to be a first-class lubricant. Castor 
oil is better for axles in the winter, and black lead 
with it is a help at any time. 
EXCHANGES. 
To exchange, $5 pair of telephones for mounted 
microscopic specimens, good objective, lathe 
chuck, watch, type and cases, or offers ; describe 
offers. Wm. R. Brooks, Phelps, N. Y. 
What offers for Roger Scroll Saw, 55 large pat- 
terns. J. Brower. 3,150 Frankford Road, Phila- 
delphia, Pa. 
Revolver, microscope, microphone, 4 magnets, 
skates, skate sharpener, copying pad, books, 
magazines, $7 worth of rosettes, and lots of other 
things to exchange ; I will give you a better trade 
than anyone else can. Chas. T. Conover, Esper- 
ance, Scho. Co., N. Y. 
Photographs of ten of the most influential In- 
dians of Spotted Tail Agency, including Spotted 
Tail and family and four oil chromos, very beau- 
tiful, for printing press, scroll saw, or offers. 
Luther Emerson, Creighton, Knox Co., Neb. 
"Appleton's Picturesque America," never been 
read or handled, value $24; "Dana's Miner- 
alogy," $10, and coins, to exchange for a breech- 
loading shot gun, Winchester or Evan's rifle, or 
offers. D. M. Fuller, Box 115, Camden, Maine. 
Scroll sawing outfit, $6 ; microscope, $3 : pocket 
telescope, $1 ; Gaskel's Compendium, $1 ; Williams' 
Complete Painters' Guide, $2. What offers for all 
or part ; printing outfit preferred, F. W. McNair, 
Box 46, Fennimore, Wis. 
$7 worth of books or papers, to exchange for a 
Household microscope or offers. Jonas D. Rice, 
221 Academy St., Mercer Co., N. J. 
One pair best steel climbing irons, handsome 
seven shot, 22 calibre revolver, full nickel plate, 
ten dollars worth of boys' papers, ,and magazines, 
for works on natural sciences or offers. W. M. 
Stribling, Circleville. Pickaway Co., Ohio. 
Will exchange phantom leaves or fern roots 
(maiden hair included), for sea mosses, shells or 
petrifactions. E. M., New Boston, Mercer Co., 
111. 
