80 
THE YOUNG SCIENTIST. 
us has three eggs attached to her in this j 
way. They are large oval bodies, with a 
firm shell. These creatures differ very 
much in appearance, according to the di- 
rection in which they are seen, and a side 
view makes them look so different from 
a full front or back aspect, that it would 
be easy to suppose another animal was 
under observation. The extent to which 
the ciliary apparatus is protruded, and 
the pattern it forms likewise differs con- 
tinually ; and hence no drawing, however 
correct, is sure to resemble the arrange- 
ment that may be presented to the ob- 
server's eye. But however our little 
" Pitcher " may be viewed, it is sure to 
prove a spectacle of interest and de- 
light. 
Burnishing. 
BY burnishing, the roughness of an ob- 
ject is flattened down until the sur- 
face is smooth and polished like a look- 
ing-glass. Burnishing is an important 
operation for electro-deposits, which con- 
sist of a multitude of small crystals, with 
intervals between them, and with facets 
reflecting the light in every direction. 
The deposited metal is hardened and 
forced into the pores of the underlying 
metal, and the durability is thus increased 
to such an extent that, with the same 
amount of silver, a burnished article will 
last twice as long as one which has not 
been so treated. The instruments em- 
l^loyed for burnishing are made of differ- 
ent'materials, and must be of great hard- 
ness and a perfect polish— such as hard- 
ened cast steel, agate, flint, and blood- 
stone. For metallic electro-deposits steel 
and bloodstone are especially employed. 
There are several qualities of bloodstone ; 
its grain should be close, hard, and with- 
out seams or veins ; it should leave no 
white lines on the burnished parts, nor 
take off any metal, and its color should 
be of an intense black red. The steel 
must be fine and close grained, and per- 
fectly ]^olished. Should the polish of any 
burnishing tool alter by use, it is restored 
by friction upon a skin or leather attached 
to a wooden block, which is fixed to the 
bench. The leather is covered with pol- 
ishing rouge in impalpable powder, or, 
l)referably, with pure alumina, obtained 
by calcining ammonia alum in a forge 
fire. Venetian tripoli, rottenstone, tin 
putty, emery, or many other hard sub- 
stances finely powdered, may be em- 
ployed. The burnishing tools are of 
various shapes, such as a lance, a tooth, 
a knife, a half sphere, or a dog's tongue, 
and a considerable stock is necessary. 
The burnishing is divided into two dis- 
tinct operations. The first consists in 
roughing, and the second in finishing. 
The toois for the first have a sharp edge, 
j while for the second operation they have 
a rounded surface. The tools for the 
hand or the lathe are fixed by copper fer- 
rules into short round wooden handles, 
so that the hand is not influenced by their 
weight. The tools for the arm or vise are 
fastened to wooden handles sufficiently 
long to rest their slender part upon the 
arm or shoulder. The stouter lower por- 
tion is grasped by the hand. The burn- 
ishing tools and the objects must be fre- 
quently wetted by certain solutions, some 
of which facilitate the sliding of the in- 
strument, or with others which have a 
chemical action upon the shade of the 
burnished articles. Of the first are pure 
water, solutions of soap, decoctions of lin- 
seed, and infusions of the roots of marsh 
mallow or licorice. The second includes 
wine-lees, cream of tartar, vinegar, alum 
in water. When burnishing gold applied 
upon electro-deposits of copper, as in 
gilding with a dead lustre by that method, 
use pure water, for fear of producing a 
disagreeable red shade. A solution of 
green soap is sometimes preferred by 
operators, although when old it imparts 
an unpleasant tinge, owing to the sul- 
phides of the liquor. When the burnish- 
ing is completed, the surface is wiped longi- 
tudinally with a soft and old calico rag. 
The polish obtained by burnishing is 
called black when it refiects the rays like 
a mirror ; and should the presence of mer- 
cury or a bad deposit prevent the tool 
from producing a bright surface, the, ob- 
ject is said to be greasy. Articles which 
have been previously polished, and which 
generally receive a very trifling deposit, 
are not burnished, but rubbed with cha- 
mois leather and the best polishing rouge. 
Too thick or too rapid electro-deposits 
cannot be burnished, but must be polished 
by rubbing with a leather and a mixture 
of oil and powdered pumice-stone, tripoli 
or tin putty. Coarse powders are used at 
the beginning, and impalpable ones at 
the end of the operation. Polished silver 
deposits are more agreeable to the eye 
than burnished ones, but the hardening 
of the latter renders them more durable. 
—Metal Worker. 
Cleansing Soiled Chamois. 
SOILED chamois is often thrown aside 
and wasted for the want of knowing 
how to clean it. Make a solution of weak 
soda and warm water, rub plenty of soap 
into the leather and allow it to remain in 
soak for two hours, then rub it well until 
it is quite clean. Afterward rinse it well 
in a weak solution composed of warm 
water, soda, and yellow soap. It must 
not be rinsed in water only, for then it 
would be so hard, when dry, as to be un- 
fit for use. It is the small quantity of 
