Year: 1893

page_text: Date of Application. 17th Apr., 1893
Complete Specification Left, 11th Jan., 1894-Accepted, 17th Mar., 1894
Similar letters refer to similar parts.
In the so called Geissler pumps the pump vessel or vacuum chamber forms the
head of a barometric tube and can be filled with mercury or emptied by raising or
lowering a quantity of mercury acting as pump piston.
The larger the pump vessel the larger a volume of the mercury piston is required
to displace the air contained in the
pump vessel.
It is the purpose of our invention to effect the displacement of air in the Geissler
pump by a piston of solid material surrounded and covered by a barometric
column of mercury forming an airtight liquid packing between the piston and the
walls of the pump vessel. The necessity of filling the whole volume of the vacuum
chamber of the pump with mercury will thereby be avoided, the quantity of
mercury required greatly reduced and the speed of working increased.
One way how this purpose may be attained is illustrated in the drawings. The
pump vessel marked A is open at the bottom and fastened to the frame F by
lugs 1.
The piston P is surrounded by a mantle M solidly connected to it at the
bottom, and may be moved up and down in a straight line between guide rails 2 by
pitman 3 and crank 4 connected to axle 5. The intermediate space between P
and M is supplied with mercury Q into which dips the lower end of vessel A.
The apparatus as represented by Figures 1 to 3 is intended to co-operate with an
auxiliary pump (not shown in the drawings) connecting with pump vessel A through
tube 6, said auxiliary pump being adapted to reduce the air pressure in A and a
receiver communicating therewith through tube 8 to a few millimeters or centimeters
of mercury pressure.
Between vessel A and the auxiliary pump a stop cock 9 is placed. When
piston P has the position as in Fig. 1 and the auxiliary pump is worked while stop
cock 9 is open, the mercury rises between P and A, until the highest vacuum
obtainable by that pump is reached, as indicated by the difference h of the mercury
levels in Fig. 1. The piston then is raised upwards and expels the air of the pump
vessel through tube 6 into the auxiliary pump which is kept working. The quantity
of mercury of the apparatus is so adjusted that the amount of mercury raised by
the auxiliary pump is sufficient to completely fill the space left between the piston
in its highest position (Fig. 2) and the top of the pump vessel, and to pass
through the bore of the stop cock 9. If then this stop cock is closed and the piston
lowered, a vacuum is created above the piston, into which the air is drawn from the
receiver through tube 8. By raising the piston again and opening the stop cock at
a suitable time this air is expelled to the auxiliary pump. This play of the pump
is repeated until the desired degree of exhaustion is attained.
Γ
into or

page_text: The range through which the piston is moved, the dimensions of P, A and M,
and the quantity of mercury contained in the apparatus must of course be selected
suitable for the purpose.
It will be noticed that the mercury of the apparatus has permanently a free
communication and passage between the inside and outside of A, so that the
difference or 1 of its level inside and outside of this vessel corresponds to the
difference of air pressure between the atmosphere and the vacuum inside of the pump
vessel.
The apparatus may be arranged on the same general principle if piston P is left
in a fixed position, and the pump vessel A raised and lowered suitably.
Several pumps of this kind may be worked from the same axle at the same
time.
Instead of the stop cock 9 an automatical valve of one of the well known types;
or a suitably constructed liquid seal valve may be inserted between vessel A and
tube 6.
The tube 8 connecting vessel A with the receiver may communicate with
vessel A at a higher place than indicated in the drawings, if a suitable valve or
its equivalent prevents the return of the air to the receiver during the upward
movement of the piston.
In cases where it is desirable to prevent the receiver to be evacuated from direct
communication with the mercury in vessel A, this may be effected by covering the
top of the mercury within vessel A by some oil or other suitable liquid.
Of course the arrangements for moving the piston, and many other details of the
pump described may be varied in many ways.
Dated this Sixth day of April 1893.
COMPLETE SPECIFICATION.
Improvement in Air Pumps.
We, HERMANN SCHULZE-BERGE of 97 York Street, Brooklyn, County of
Kings, State of New York, United States of America, Chemist, and FRANZ
SCHULZE-BERGE of 97 York Street, Brooklyn, County of Kings, State of New
York, United States of America, Electrician, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
Our invention refers to mercurial air pumps and is illustrated by the accom-
panying drawings in which
Fig. 1 shows one form of our apparatus in a vertical section..
Fig. 2 represents the same in a different position, while
Fig. 3 is a cross section of the apparatus in the line X Y.
Fig. 4 shows a modified form of our apparatus in a vertical section.
Fig. 5 represents the same in a different position.
One sheet of drawings, containing Figures 1 to 3, was filed with the Provisional
Specification.
Similar letters refer to similar parts.
In the so called Geissler pumps the pump vessel or vacuum chamber forms the
head of a barometric tube and can be filled with mercury or emptied by raising or
lowering a quantity of mercury acting as pump piston.
The larger the pump vessel the larger a volume of the mercury piston is required
to displace the air contained in the pump vessel:
:
It is the purpose of our invention to effect the displacement of air in the Geissler 5
pump by a piston of solid material surrounded and covered by a barometric column
of mercury forming an airtight liquid packing between the piston and the wall of
the pump vessel.

page_text: The necessity of filling the whole volume of the vacuum chamber of the pump
with mercury will thereby be avoided, the quantity of mercury required greatly
reduced and the speed of working increased.
One way how this purpose may be attained is illustrated by Figs. 1 to 3 of the
drawings. The pump vessel marked A is open at the bottom and fastened to the
frame F by lugs 1. The piston P is surrounded by a mantle M solidly connected to
it at the bottom, and may be moved up and down in a straight line between guide
rails 2 by pitman 3 and crank 4 connected to axle 5. The intermediate space
between P and M is supplied with mercury Q into which dips the lower end of
vessel A.
The apparatus is intended to co-operate with an auxiliary air pump (not shown
in the drawings) connecting with pump vessel A through tube 6, said auxiliary
pump being adapted to reduce the air pressure in A and a receiver communicating
therewith through tube 8 to a few millimeters or centimeters of mercury pressure.
Between vessel A and the auxiliary pump a stopcock 9 is placed.
When
piston P has the position as in Fig. I and the auxiliary pump is worked while
stopcock 9 is open, the mercury rises between P and A, until the highest vacuum
obtainable by that pump is reached, as indicated by the difference h of the mercury
levels in Fig. 1. The piston then is raised upwards and expels the air of the
pump vessel through tube 6 into the auxiliary pump which is kept working. The
quantity of mercury of the apparatus is so adjusted that the amount of mercury
raised by the auxiliary pump is sufficient to completely fill the space left between
the piston in its highest position (Fig. 2) and the top of the pump vessel and to
pass into or through the bore of the stopcock 9. If then this stopcock is closed
and the piston lowered, a vacuum is created above the piston into which the air is
drawn from the receiver through tube 8. By raising the piston again and opening
the stopcock at a suitable time this air is expelled to the auxiliary pump. This
play of the pump is repeated until the desired degree of exhaustion is attained. The
range through which the piston is moved, the dimensions of I, A and M, and the
quantity of mercury contained in the apparatus must of course be selected suitable
for the purpose.
It will be noticed that the mercury of the apparatus has permanently a free
communication between the inside and outside of A.
The apparatus may be arranged on the same general principle if piston P.is
left in a fixed position, and the pump vessel A raised and lowered suitably. .
On the other hand the pump may be arranged so as to work without the
co-operation of an auxiliary pump. If vessel A is so mounted that the mantle M
may be prolonged upwards beyond the height at which stopcock 9 is placed; and if
this mantle is made wide enough to comprise tube 8, it only is necessary to fill the
mantle with mercury while the piston occupies the position shown in Fig. 2, to
expel all air from vessel A through stopcock 9. By lowering and raising the
piston P a receiver may then be evacuated just as with an ordinary Geissler
pump.
Several pumps of the kind described may be worked from the same axle at the
same time.
Instead of the stopcock 9 an automatical valve of one of the well known types, or
a suitably constructed liquid seal valve may be inserted between vessel A and
tube 6.
The tube 8 connecting vessel A with the receiver may communicate with
vessel A at a higher place than indicated in the drawings, if a suitable valve or
its equivalent prevents the return of the air to the receiver during the upward
movement of the piston.
A somewhat different arrangement is represented by Figures 4 and 5. The
pump vessel or vacuum chamber is again marked A. It consists of a hollow
cylinder open at the bottom and covered with a conical roof from the center of
which starts the tube 6. An automatic air valve 9¹ of one of the well known
types is inserted into tube 6. The interior of the pump vessel also communicates

page_text: with tube 8 leading to the vessels to be exhausted. The pump vessel A is
airtightly inserted into the cover C of the larger vessel D. A forked tube T
passes through the cover and contains in its branches the stopcocks S1 and S2.
A cylindrical vessel G closed at its top is located concentrical with D. The
lower edges of G and D are connected by the rim K, an annular space being left
free between D and G.
A piston P1 (Fig. 5) is contained in the apparatus, consisting of the conical
cover L, the cylindrical wall W and the mantle M 1 connected to the lower end
of W by the rim N. The intermediate space between M 1 and W is supplied with
inercury Q. It is obvious from this description that piston P 1 can be raised from
its position in Fig. 4 until its roof approaches the roof of A, as in Fig. 5.
This apparatus is supposed to co-operate with two auxiliary air pumps (not
shown in the drawings) capable of producing a vacuum of some millimeters of
mercury pressure. One of the auxiliary pumps is permanently connected to tube 6,
while the second one connects with the branch R of the forked tube T.
After the vessels to be exhausted are connected to tube 8, the two auxiliary
pumps are worked so as to produce within vessel D, pump vessel A and the vessels
to be exhausted such a vacuum as they allow to create. If then stopcock S1 is
closed and air slowly admitted into D through stopcock S2, the mercury will sink
between M1 and the wall of A, and will rise between said wall and W. At the
same time the difference of air pressure acting upon the piston within D and A
respectively tends to raise this piston upwards, and as soon as the force exerted
reaches a certain amount easily to be calculated from the dimensions and the weight
of the piston the latter is actually lifted and moved into the position shown in
Fig. 5. The increasing air pressure within D will continue to raise the mercury
between W and A until it fills completely the intermediate space between PI
and A and just passes the valve 9¹. At this moment stopcock S2 is closed and
stopcock S1 opened in order to reduce the pressure in D by the second auxiliary
pump. The mercury then sinks between P1 and A, and after a certain reduction
of pressure, piston P1 will sink down again into its initial position, leaving above
its cover an improved vacuum into which the air is drawn from the vessels connected
to 8. It is evident how the play of the machine is to be repeated by alternately
increasing and decreasing the air pressure in D, until the desired degree of
rarefaction is reached in the vessels to be exhausted.
$6
"
The height of the barometric mercury column required to expel the air through
valve 91 may be about equal to, or less than the height corresponding to one
atmosphere according to the height of the apparatus and the range of pressure
used. What we wish to designate by the term a barometric column is a liquid
column suspended by a difference of air pressure acting on its levels, according to
a similar principle as by which the mercury is suspended in a barometer. The
quantity of mercury contained in the apparatus, the weight and dimensions of the
piston and the proportions of the different parts of the machine must of course be
selected in accordance with the purpose described. If the diameter of A is made
sufficiently large, the amount of vacuum obtained by a single stroke of the piston
can be made extremely large while still only a very moderate range for the motion
of the piston would be required.
It is of course necessary to properly guide the piston in its oscillations.
The stationary vessel G serves this purpose in the machine illustrated by the
drawings.
It is a peculiar and essential advantage of the pumps described that the interior
of the same is easily accessible for cleaning, by removing the cover C of D
together with the vessel A, while generally the cleaning of a mercury pump is
considered a troublesome task on account of the inaccessibility of the pump
vessel.
As material for the different vessels of the apparatus described preferably iron
or steel is used enameled on all parts which come into contact with mercury. Glass,
china or their equivalent would answer also, but would be more exposed to

page_text: destruction by accident, as is well known from the unpleasant breakage so
frequently occurring with the usual form of Geissler pumps.
The valve 9' (Fig. 4) may be replaced by a stopcock or a liquid seal of suitable
construction or some other equivalent device. All the stopcocks used in the
apparatus may easily be arranged so as to be moved mechanically by machinery at
the proper time.
Other liquids than mercury can be used in the pump if the dimensions of the
apparatus are selected in accordance with the specific gravity of the liquids.
concerned.
•
The air pumps described above clearly illustrate the general principle of their
construction. In practice a great variety of different constructions may be carried
out according to this principle. We do not want to limit ourselves to the special
constructions explained, but wish to cover broadly the principle of using in a
mercurial air pump a piston of solid material reaching into the vacuum chamber
and 'adapted to displace, in combination with a barometric liquid column, the air of
said vacuum chamber.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
1. In an air pump a piston of solid material reaching into the vacuum chamber
of the pump and adapted to displace, in combination with a barometric liquid
column, the air of said vacuum chamber, substantially as and for the purpose
described.
2. In a mercurial air pump a piston of solid material adapted to be covered by a
barometric column of mercury and adapted to be raised and lowered within the
vacuum chamber of the pump, substantially as and for the purpose described.
3. In a mercurial air pump a piston of solid material adapted to be covered by a
barometric column of mercury and adapted to be raised and lowered within the
vacuum chamber of the pump by a variation of the air pressure acting upon said
piston, substantially as and for the purpose described.
Dated this Third day of January 1894.
HERMANN SCHULZE-BERGE.
FRANZ SCHULZE-BERGE.