Essays on the Microscope: Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.Adams, George
Science
Essays on the Microscope: Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.
Adams, George
Insects -- Early works to 1800; Microscopy -- Early works to 1800
The small ball is now to be separated from the thread of glass; this is
easily effected by the sharp edge of a piece of flint. The ball should
be placed in a groove of paper, and another piece of paper be held over
it, to prevent the ball from flying about and being lost. A quantity of
globules ought to be prepared in this manner; they are then to be
cleaned, and afterwards placed in the cavities of the tripoli, by means
of a delicate pair of nippers. The globules are now to be melted a
second time, in order to render them completely spherical; for this
purpose, bring one of the cavities near the extremity of the flame,
directing this towards the tripoli, which must be first heated; the
cavity is then to be lowered, so that the flame may touch the glass,
which, when it is red hot, will assume a perfect globular form; it must
then be removed from the flame, and laid by; when cold, it should be
cleaned, by rubbing between two pieces of white paper. Let it now be set
in a brass cap, to try whether the figure be perfect. If the object be
not well defined, the globule must be thrown away. Though, if it be
large, it may be exposed two or three times to the flame. When a large
globule is forming, it should be gently agitated by shaking the tripoli,
which will prevent its becoming flat on one side. By attending to these
directions, the greater part of the globules will be round and fit for
use. In damp weather, notwithstanding every precaution, it will often
happen, that out of forty globules, four or five only will be fit for
use.
Public-domain text, read in full here on John Shaqi.
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