THE YOUNG SCIENTIST. 
75 
of the work being rounded off at the ends, sides, 
'and anything but flat. No matter; all the ex- 
pressions of regret at this result, occurring so 
many times without any improvement, will 
not alter matters. Patience and practice are 
all that the tyro at the vice requires, and after a 
certain time he will find, probably to his sur- 
prise, that the piece he is filing is inclined to 
favor him by becoming something approaching 
flat. This is encouraging, and fresh vigor is 
instilled into the man, file, and apparently ma- 
terial, as a certain amount of improvement is 
evident at each successive trial. And I think 
that if, after a few months, for it will not be 
properly instilled into any one in less time, 
whoever tries can then feel certain of perform- 
ing this feat of filing a flat surface, he will be 
well repaid for the time and study he has de- 
voted to it. 
To he Continued. 
Labelling Bottles. 
A writer in the English Mechanic says: 
" There is no plan so good as one I use. Affix a 
common paper label and let it dry; then heat 
the label (by a Bunsen burner or very small 
flame) till it will just melt paraffine rubbed on 
it. The label is absolutely protected, and looks 
as if it were enameled on the glass. If the neck 
and lip of the bottle and the stopper are simi- 
larly treated, a perfect air-tight jomt is secured 
and the stopper never sets, while liquids can be 
poured out without running down the sides." 
Case-Hardening-.— If a surface case-hardened 
with prussiate of potash appears of a dirty black, 
it is because it has not been properly done, for a 
prussiate of potash, weU-hardened job, is white, 
without a single shade of black anywhere, and is 
Quite as hard as any case-hardening. 
Again, any form of hardening that leaves the 
surface otherwise than wliite, does not thoroughly 
harden, or, in other words, the fancy colors on 
such work evidence that it is only partly hard- 
ened, and, as a rule, can be cut by tlie edge of a 
sharp smooth file, if well-pressed to the work. 
These are facts none too well known, and just 
the points that your paper ean do a world of good 
in bringing out— Blacksmith and Wheelwright. 
Cleaningr Brass.— The following directions 
have been given by a correspondent of the Artizan 
(London):— Make a mixture of one part common 
nitric acid and one-half part sulphuric acid in 
a stone jar; then place ready a pail of fresh water 
and a box of sawdust. Dip the articles to be 
cleaned in the acid, then remove them into the 
water, after which rub them with sawdust. This j 
immediately changes them to a brilliant color. If 
the brass is greasy, it must be first dipped in a. 
strong solution of potash and soda in warm water. 
This cuts the grease so that the acid has the 
power to act. This is a government recipe used 
in the arsenals. We will add to the above recipe 
that first washing in clean water, and second in 
water in which aqua ammonia has been placed to 
neutralize all trace of the remaining acid upon the 
surface of the brass, is an improvement upon the 
above process, which is in all other respects, a 
good one. After dipping in the ammonia water 
and cleaning in the sawdust, if a good quality of 
lacquer be used, the effect is very fine. This pro- 
cess is excellent in preparing brass labels stamped 
from thin sheets. 
Flower-pots in the Liaboratory.— A flower- 
pot makes an excellent lamp screen, for steady- 
ing and concentrating the flame under evaporat- 
ing basins, etc. ; of course a sufficient interval 
must be kept between the pot and the basin, else 
the light will be extinguished. 
A small flower-pot with wire gauze tied over the 
top is a very effective low temperature lamp when 
the gas is lighted below the gauze. If the gas is 
lighted above the gauze we have a capital argand 
lamp giving a large, clear blue flame. In the lat- 
ter case a common burner can be used, a con- 
sideration when Bunsen's are all temporarily 
occupied or not available. After a time the pots 
become cracked from the heat, but as they are 
easily replaced this does not matter, and even 
when cracked they will often hold out for a con- 
siderable time. Fireclay flower-pots made rather 
thick would, however, afford a really good and 
cheap portable furnace. 
By placing the flower-pot inside another just 
large enough to encase it. loss of heat by radia- 
tion would be effectually checked. 
To Pulverize Shellac— Any one who has 
tried to pound up shellac in a mortar knows that 
the attempt is more favorable to perspiration and 
profanity than to the pulverization of the slippery 
stuff. A correspondent of the Druggists' Circular 
has devised the following method: " Enclose the 
shellac in a strong, closely-woven piece of cloth, 
at first compressing the folds rather tightly, but 
gradually relaxingthem. Then, after placing the 
bunch, which must be held in position with the 
hand, upon a solid block or smooth coimter, the 
strokes of a heavy iron pestle are applied, gently at 
first, while the bunch is kept mov ng from side to 
side, so as to expose every part to the strokes of the 
pestle. After the large, sharp pieces are broken, 
the strokes are increased in velocity and power, 
with wonderful effect upon the resin, and but lit- 
tle injury to the cloth. In this way shellac may 
beredu(^ed to agranular form sufficiently fine for 
pyrotechnic purposes at very short notice, and to 
an almost impalpable powder in a comparatively- 
short space of time. To produce this result, how- 
ever, it is necessary to wield the pestle forcibly, 
and then from time to time separate the finer 
I particles from the coarser by sifting." 
