14 
THE YOUNG SCIENTIST. 
ters ! Some years ago we tested this very care- 
fully, and found that while a thermometer, 
screened from the rays of the sun, showed but 
S° above zero, a similar thermometer, with the 
toulb blackened and screened from draughts of 
air, showed 165° ! ! 
A Lubricator for Whetstones. 
A French journal suggests, as a substitute for 
oil in sharpening tools, a mixture of glycerine 
and alcohol. The proportions of the mixture 
vary according to the instrument operated on. 
An article with a large surface, a razor, for in- 
stance, sharpens best with a limpid liquid, as 
three parts of glycerine to one part of alcohol. 
'For a graving tool, the cutting surface of which 
is yei'y small, and the pressure exercised on the 
stone in sharpening very great, it is necessary to 
•employ glyc(Hine almost pure, with but two or 
three drops of alcohol. 

A Brilliant Coating* for Ornaments. 
The appearance of articles manufactured by 
amateurs, and intended for mantel-piece and 
other ornaments, may often be greatly im- 
proved by coating them with the following 
preparation : Plates of mica are first rendered 
perfectly clean and white, either by boiling in 
muriatic acid or by igniting them; they are 
then washed, dried, and ground to a fine powder, 
which is thoroughly sifted and mixed with very 
thin collodion. In this condition it is applied, 
like paint or varnish, with a soft pencil, two or 
three more coats being given to the article until 
the desired thickness is obtained, which is de- 
termined, of course, by the taste and judgment 
of the workman. The objects thus coated have 
a silvery appearance, and possess the valuable 
advantage o\er those in which the ordinary 
metallic bronze is employed, of not being at all 
affected by sulphurous vapors ; neither are they 
injured by dust or dirt, and are readily cleaned 
Toy washing in water. Collodion adheres firmly 
to glass, porcelain, wood, metal, and pasteboard ; 
and as mica is capable of taking any desired 
•color, at the same time retaining completely the 
lustrous appearance distinguishing it, it fur- 
nishes by this process an exquisite covering for 
a large variety of articles. 
Doing Much.. 
Many persons seem always to be in a hurry, 
and yet never accomplish much; others never 
to be hurried, and yet do a great deal. If you 
have fifty letters to answer, don't waste time in 
looking over and pondering which one you will 
answer first; arrange them without much 
thought in the order of their importance, and 
then go through the whole pile. Some begin a 
thing, aad have it partially completed, and 
hurry off to something else. A better plan is to 
complete whatever you undertake before you 
leave it, and be thorough in everything ; it is the 
going back from one thing to another that 
wastes valuable time. Deliberate workers are 
those who accomplish the most work in a given 
time, and are less tired at the end of the day 
than many who have not accomplished half as 
much ; the hurried worker has often to do his 
work twice over, and even then it is seldom done 
in the best manner, either as to the neatness or 
durability. It is the deliberate and measured 
expenditure of strength which invigorates the 
constitution and builds up the health; multi- 
tudes of firemen have found an early death, 
while the plow boy lives healthily and lives 
long, going down to his grave beyond three 
score and ten. 
French Polishing. 
This operation requires practice to ensure 
success, but is easily acquired. The surface of 
the wood should be thoroughly smooth, and the 
grain well filled. Rub down with finest sand- 
paper until of a uniform greyish tint, without 
scratches, and remove dust with a dry warm 
cloth. Make a wad of flannel or wadding ; satu- 
rate this with French polish, and wrap in an old 
piece of printed cotton or soft rag. Touch the 
rag with two or three drops of raw linseed oil, 
and rub the work in a circular direction. Do not 
allow the rubber to stick. AVhen the surface is 
well bodied in, finish off in the same manner, 
but with two-thirds polish to one-third alcohol. 
In other words, thin the polish in the rubber 
every time it is saturated, until the wood is as 
bright as plate glass. Twenty-four hours should 
elapse before the finishing process is com- 
menced. 
Working" Hard Metals. 
Metal workers know that some alloys are i 
very hard to drill or turn in the lathe. So are 
phosphor bronzes, the aluminum bronzes, and ; 
even the alloy of 7 parts zinc, 4 of copper, and 1 \ 
of tin, with which a Paris mechanic lately ex- | 
perienced much difficulty. He remembered,/ 
however, that even hard glass may be cut with ! 
a good steel drill when it is lubricated with tur- ; 
pentine, and so he tried this on hard bronze 
Avith good success. The best material he found • 
to be petroleum, mixed with turpentine spirits, [ 
witli the help of which the tools, which other- ; 
wise soon became blunt, retained their cutting 
edges. He found that even hard steel, only 
slightly tempered to a straw-yellow, could be | 
easily cut in this way with good chisels and [ 
drills made rather harder than usual. 
I 
