Bresser NATIONAL GEOGRAPHIC 40X-1024X Mode D'emploi page 15

DANGER!
Be exremely carfeful when dealing with hot wax, as there is a danger
of being burned.
Then, dip the specimen several times in the liquid wax. Allow the wax that encases
the specimen to harden. Use a MicroCut (19) or other small knife or scalpel to
make very thin slices of the object in its wax casing.
DANGER!
Be extremely careful when using the MicroCut, knife or scalpel.
These instruments are very sharp and pose a risk of injury.
Place the slices on a glass slide and cover them with another slide before attempt-
ing to view them with the microscope.
6�3� Creation of your own preparation
Put the object to be observed on a glass slide and cover the object with a drop of
distilled water (No. 3) using the pipette (No. 3, 17a).
Set a cover glass (available at a well-stocked hobby shop) perpendicular to the
edge of the water drop, so that the water runs along the edge of the cover glass
(No. 4). Now lower now the cover glass slowly over the water drop.
TiP:
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The gum medium (20b) supplied is used to make permanent slide
cultures. Add it instead of distilled water.
The gum medium hardens so that the specimen is permanently
affixed to its slide.
7� Experiments
Now that you're familiar with your microscope's functions and how to prepare
slides, you can complete the following experiments and observe the results under
your microscope.
7�1� Newspaper print
Objects:
1. A small piece of paper from a newspaper with parts of a picture and some
letters
2. A similar piece of paper from an illustrated magazine:
Use your microscope at the lowest magnification and make a slide preparation
from each object. Place the slide with the newspaper on the microscope table and
observe the slide. The letters in the newspaper appear broken because the news-
paper is printed on raw, inferior paper. Now observe the slide with the magazine
preparation. Letters of the magazine appear smoother and more complete. The
picture from the newspaper consists of many small points, which appear somewhat
dirty. The pixels (raster points) of the magazine image appear sharper.
7�2� Textile fibres
Objects and accessories:
1. Threads of different textiles: Cotton, linen, wool, silk, Celanese, nylon and
any others you can find.
2. Two needles:
Put each thread on a glass slide and fray each with the help of the two needles. Put
a drop of water over each thread with the pipette and cover each with a cover glass.
Adjust the microscope to a low magnification. Cotton fibres are of plant origin and
look, under the microscope, like a flat, twisted band. The fibres are thicker and
rounder at the edges than in the centre. Cotton fibres consist primarily of long, col-
lapsed tubes. Linen fibres are also of plant origin; they are round and run in straight
lines. The fibres shine like silk and exhibit numerous swellings along the shaft of
the fibre. Silk is of animal origin and consists of solid fibres of smaller diameter than
the hollow vegetable fibres. Each silk fibre is smooth and even and has the appear-
ance of a small glass rod. Wool fibres are also of animal origin; the surface consists
of overlapping scales, which appear broken and wavy. If possible, compare wool
fibres from different weaving mills, and note the differences in the appearance of
the fibres. Experts can determine the country of origin of wool based on its appear-
ance under a microscope. Celanese is artificially manufactured by a long chemical
process. All Celanese fibres show hard, dark lines on a smooth, shining surface.
EN
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