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THE YOUNG SCIENTIST. 
THE 
YOUNG SCIENTIST. 
Published Monthly at 50 cents per year. 
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Care of the Microscope. 
T^HERE is scarcely any instrument that is 
J- more easily injured by rough usage than 
the microscope, and there is none that is more 
durable, provided proper care be taken of it; 
and as microscopes are as frequently injured 
from want of knowledge as from want of at- 
tention, a few hints may not be out of place. 
The great enemy of the microscopist, both in 
regard to the preparations on which he spends 
so much labor and the instrument which he 
uses for examining them, is dust. To the 
microscope itself, dust is utterly destructive. 
It not only dims the glasses and makes specks 
on them which appear to be part of the object, 
and thus cause errors, but it gets into the 
working parts, grinds them and wears them 
out rapidly, destroys the accuracy and evenness 
with which they move, and clogs them so that 
great force is needed where force should not 
be applied. Often and often we have seen 
microscopes sent to the maker for repairs, 
which only needed cleaning. 
The first thing then is to exclude dust. The 
microscope should never be exposed except 
when it is in use, and then it should be kept 
from all extra invasions of dust. When not in 
use it should be kept in its case, and as the 
taking out and putting back of the instrument 
is always more or less of a bother, the case 
should be made to receive it without any 
necessity for its being unscrewed or taken 
apart except in the case of travelling micro- 
scopes or seaside microscopes, where great 
compactness and portability are desired. Hence 
the upright case should always be chosen, and 
it should be large enough to take in the mi- 
croscope with its eye-piece attached. If it 
gives much trouble to take the microscope out 
of its case, the instrument will often lie un- 
used when great advantage might be derived 
from employing it, and this not on account of 
the laziness of the owner, but simply because 
he has not time. When it takes ten minutes 
to get the microscope ready and five minutes to 
examine the object, the examination will not 
be made if we have only ten minutes at our 
disposal. 
The case, of whatever shape, should close 
tightly, and if kept in a region where the du^t 
is plentiful and of a very grinding character, a 
thick covering of some close material, like oil- 
cloth or leather, should be thrown over it. It 
should be so loose that it shall be but a mo- 
ment's work to take it off or put it on, and it is 
best made in the form of a case or bag, the 
edges of which are firmly sewed together. 
Ordinary porous cloth allows dust to pass, and 
will not answer. 
When, in spite of all precautions, the micro- 
scope has been soiled, it should be carefully 
cleaned, and for this we will give directions in 
our next issue. 
Examination of Powders. — A New Employ- 
ment for the Microscope. 
The value of many materials that are used in the 
arts depends very much upon the degree of fineness 
to which they are reduced to powder. This is usually 
judged by the sense of feeling — a little of the powder 
being rubbed between the fingers. In some cases the 
appearance of the powder as to color and its behavior 
when laid in a little heap, and moved about with a 
knife or spatula, is a good guide. Most substances, 
when reduced to very fine powder, behave like fluids 
in some respects and like solids in others. For ex- 
ample, they can be made into a heap with a perpen- 
dicular fiice, which cannot be done with sand for 
example. (Try this with flour or with silica — sand 
very finely powdered). But the most accurate way 
of judging of the fineness of powders is by the micro- 
scope. Under a power of 100 diameters, most pow- 
ders look coarse ; 250 shows well some powders which 
