The most ancient of such instruments is certainly the syringe. The
Egyptians, says Herodotus (ii., 87), employed the latter in the
embalming of common people, for filling the belly with oil of cedar,
through injections made _per ano_, without opening the body and
extracting the intestines. Heron, in his "Pneumatics," describes an
instrument of this kind, called _Pyulgue_, which was designed for
sucking pus out of wounds.
The following apparatus, also described by Heron, is the first step
that was taken toward the production of the pneumatic apparatus
properly so called
"_Construction of a cupping glass that sucks without the aid of fire_."
Let _ΑΒΓ_ (Fig. 1) be a cupping glass (like that which is usually
applied to the skin), divided by a partition, _ΔΕ_. Through the bottom
let there be passed two tubes that slide one within the other by
friction--_ΖΗ_ being the external and _ΘΚ_ the internal one. In these
two tubes, external to the glass, there are two apertures, _ΛΜ_, that
face each other. The extremities of the tubes situated within the
apparatus should be open, and the external extremity of _ΘΚ_ should
be closed and provided with a key. Beneath the partition, _ΔΕ_, there
is another cock, _ΝΞ_, like the one just described, save that the
corresponding apertures are within the cupping-glass, and are in
communication with an aperture in the partition, _ΔΕ_.
"Things being arranged thus, the keys of the cock are revolved in such
a way that the apertures of the one at the bottom of the instrument are
in a line with each other, while the cock above the partition remains
closed, inasmuch as its apertures do not correspond. The chamber, _ΔΓ_,
being full of air, if we apply the mouth to the orifices, _ΛΜ_, and
suck out a portion of the air, and turn the key of the cock without
removing the mouth from the tube, we shall be able to thus keep up a
rarefaction of the air in the chamber, _ΓΔ_. The oftener we perform
this operation, the more air we shall remove. Let us now apply the
cupping-glass to the skin in the usual way, and open the cock, _ΝΞ_, by
turning the key. A portion of the air contained in _ΑΔΕ_ will pass into
_ΓΔ_, and we shall then see the skin, as well as the subjacent matters
that pass through its interstices, that we call unexplored spaces,
drawn into the space in which the air is rarefied."
As for the pressure fountain, this had reached perfection as long ago
as the Alexandrine epoch. The following description of it is borrowed
from the "Pneumatics:"
"_To construct a hollow sphere, or any other vessel, in which, if a
liquid be poured, the latter may be made to rise spontaneously with
great force so as to empty the vessel, although such motion be contrary
to nature_."
"The construction is as follows: Let there be a sphere of a capacity
of about six cotyles (about 2¾ pints) made of some metal tough enough
to withstand the pressure of the air that is to be produced. Let us
place this sphere, _ΑΒ_, upon any base whatever, _Γ_. Through an aperture
in its upper part we introduce a tube which runs down to that part of
the sphere which is diametrically opposite the aperture, but which
leaves sufficient space there for the water to pass. This tube projects
slightly above the sphere, to whose aperture it is soldered, and
divides into two branches, _Η_ and _Ζ_, to which are affixed two bent
tubes, _ΖΜΝΞ_ and _ΗΘΚΛ_, that communicate internally with _Η_ and _Ζ_.
Finally, in these tubes, _ΗΘΚΛ_ and _ΖΜΝΞ_, and in communication with
them, there is adapted another tube, _ΠΟ_, from which issues at right
angles a small tube, _ΡΣ_, that communicates with it and terminates at
_Σ_ in a fine orifice.
If, taking the tube, _ΡΣ_, in hand, we revolve the tube, _ΠΟ_, the two
apertures that face each other can no longer establish a communication,
and the liquid that rises will no longer find an outlet. Then, through
another aperture in the sphere, we insert another tube, _ΤτΦ_, whose
lower orifice, _Φ_, is closed, but which has upon the side, toward the
bottom, at _Χ_, a round hole to which is adapted a small valve of the
sort called by the Romans _assarium_. Into the tube, _τΦΤ_, we insert
another and closely fitting tube, _ΨΩ_. Let us now remove the tube,
_ΨΩ_, and pour liquid into the tube, _τΦΤ_. This liquid will enter the
cavity of the sphere, through the aperture, _Χ_. The valve will open in
the interior, and the air will escape through the apertures in the
tube, _ΟΠ_, of which we have already spoken, and which have been so
arranged as to communicate with the tubes, _ΗΘΚΛ_ and _ΖΜΝΞ_. When once
the sphere is half full of liquid, we incline the small tube, _ΡΣ_, so
as to shut off all communication between the corresponding apertures,
and then push down the tube, _ΨΩ_, and drive into the interior of
the sphere the air contained in _ΤτΦ_. This requires some force, as
the sphere itself is full of liquid and air, but the introduction is
rendered possible through the compression of the air, which shrinks
into the empty spaces that it contains within itself. Let us now take
out the tube, _ΨΩ_, again so as to fill the tube, _ΤτΦ_, with air, and
let us push down the tube, _ΨΦ_, again and force this air into the
sphere. On repeating this operation several times in succession we
shall finally have in the sphere a large quantity of compressed air.
It is clear, in fact, that the air introduced by force cannot escape
when the piston-rod is raised, since the valve, pressed by the internal
air, remains closed. If then, replacing the tube, _ΡΣ_, in a vertical
position, we set up a communication again between the corresponding
apertures, the liquid will be driven to the exterior through the
compressed air, and the latter will assume its normal volume again,
and press in the liquid beneath it. If the quantity of compressed air
is considerable, there will occur an expulsion, not only of the entire
liquid, but also of the excess of air.
[Illustration: Fig. 1.--HERON'S CUPPING GLASS.]
The valve of which I have spoken is constructed as follows (Fig. 2, 1
_bis_ and 1 _ter_): Take two pieces of brass about one inch square, and
about as thick as a carpenter's rule, and rub their surfaces against
each other with emery, that is to say, polish them so that neither air
nor liquid can pass between them. In the middle of one of the pieces
bore a circular aperture about 4/10 an inch in diameter. Then fitting
the two plates together by one of their edges, unite them by a hinge so
that the polished surfaces shall coincide with each other. When this
valve is to be made use of, the part containing the aperture is adapted
to the aperture that is designed for the introduction of the liquid or
air that is to be compressed. The pressure causes the other part of the
valve (which moves easily on its hinge) to open and allow the liquid
or air to enter the tight vessel, wherein it is afterward confined and
presses against the unperforated part of the valve and thus closes the
aperture through which the air entered."--_A. de Rochas, in La Nature_.
[Illustration: Fig. 2.--HERON'S FOUNTAIN.]
* * * * *
PROFESSOR ADOLF MEYER has been experimenting upon the relative
digestibility of natural and artificial butter. The experiments were
made on a man of 39, and a boy of 9 years. He found that there was
but little difference, but in these individuals the natural butter
seemed to be more easily digested. While natural butter was all
digested, at least 98 per cent. of the artificial butter was also
digested.--_Chemiker Zeit_.
* * * * *