It is desirable to reduce the temperature of the substances
previously, if convenient, by placing the vessels in water, with nitre
powder thrown in occasionally.
_Microscopic Examination of the Blood_.
By the aid of Tulley's achromatic microscope, and under highly
magnifying powers, it has recently been discovered that the globules
of the blood congeal into flat circular bodies, and arrange themselves
in rows, one body being placed partly underneath another, and in like
manner as a pile of similar coins, when thrown gently down, would be
found to arrange themselves. This curious effect has been attributed
to the vitality yet remaining in the blood, during the act of
congealing. At any rate it is a most singular fact, for although we
might naturally conceive that the flattened circular plates would
place themselves in juxtaposition, yet we never could have supposed
that they would have partly slipped underneath each other. In order to
make this very curious experiment, it is necessary that the blood, as
freshly drawn, be slightly and thinly smeared over the surface of a
slip of crown, or window glass, and be covered with a very thin slip
of Bohemian plate glass; and thus some slight inequalities in the
thickness of the layer of blood between them will be produced, and
which are necessary to succeed in producing the very curious
appearances abovementioned.
Pages:
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62