An Improvement in Mercury Vacuum Pumps.
Year: 1890

page_text: Date of Application, 12 h Dec., 1890
Complete Specification Left, 26th Aug., 1891-Accepted, 26th Sept., 1891
PROVISIONAL SPECIFICATION.
An Improvement in Mercury Vacuum Pumps.
I, EDWARD CHARLES CYRIL BALY of the Bank of England, in the County of
London, Chemical Student, do hereby declare the nature of this invention to be as
follows:-
My invention relates to vacuum pumps of the kind wherein a body of mercury is
lowered so as to exhaust into a vacuous chamber, and raised so as to displace
from that chamber such air as may have been drawn into it. The chief object of
my invention is to simplify the construction and action of such pumps and
particularly to avoid the use of valves which are expensive to make and trouble-
some to maintain working.
The accompanying drawing is a diagrammatic section of a mercury vacuum
pump according to my invention all the parts being of glass hermetically worked
together. The tube V connected to the vessel or vessels that are to be exhausted
leads to the tube C which extends downwards more than 30 inches and is connected
at its lower end by a flexible tube to a mercury vessel which is raised and lowered
in the usual way.
G is the main vacuum chamber above which are two subsidiary
chambers A and B. Of these, the chamber A is connected to G by a short tube D
terminating a little above the bottom of A, in a short siphon bend of small bore.
The chamber B is connected to A by a tube E which also terminates in a siphon
bend of small bore. From the chamber B above the mouth of the siphon bend a
tube H, which may be of small bore leads down more than 30 inches to drain off
any mercury that may pass through E down to a well K from which it can over-
flow to any convenient receptacle. The chamber B is connected through a pipe
and stopcock F to an air exhausting pump worked by hand or otherwise so as to
maintain a partial vacuum throughout the apparatus which operates as follows.
The air pump connected at F so far rarefies the contents of B, that, if there should
be an absolute vacuum in A there is not sufficient excess of pressure in B to
overcome the column of mercury in the downward limb of E which consequently
acts as a seal.
The external mercury vessel is raised so that the mercury charges G and A and
just overflows into B. The vessel is then lowered and the mercury descends from A
and G leaving a torricellian vacuum in A and also in G until rarefied air from V
passes into G. When the mercury is again raised, the air is driven from G into A
and thence into B, and thus by alternately raising and lowering the mercury, the
contents of the vessels connected to V are more and more rarefied.
Dated this 12th day of December 1890.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improvement in Mercury Vacuum Pumps.
I, EDWARD CHARLES CYRIL BALY, of the Bank of England, in the County of
London, Chemical Student, 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:-
My invention relates to vacuum pumps of the kind wherein a body of mercury is
lowered so as to exhaust into a vacuous chamber, and raised so as to displace from
that chamber such air as may have been drawn into it.

page_text: The chief object of my invention is to simplify the construction and action of
such pumps and particularly to avoid the use of valves which are expensive to
make and troublesome to maintain working.
The drawing accompanying my Provisional Specification is a diagrammatic
section of a mercury vacuum pump according to my invention all the parts being of
glass hermetically worked together.
The tube V connected to the vessel or vessels that are to be exhausted leads to
the tube C which extends downwards more than 30 inches and is connected at its
lower end by a flexible tube to a mercury vessel which is raised and lowered in the
usual way.
G is the main vacuum chamber above which are two subsidiary
chambers A and B. Of these, the chamber A is connected to G by a short tube Ď
terminating a little above the bottom of A, in a short siphon bend of so small a
bore as to permit of the mercury going over in a solid body. The chamber Bis
connected to A by a tube E which also terminates in a siphon bend of so small a
bore as to permit of the mercury going over in a solid body.
From the chamber B above the mouth of the siphon bend a tube H, which may
be of small bore leads down more than 30 inches to drain off any mercury that may
pass through E down to a well K from which it can overflow to any convenient
receptacle. The chamber B is connected through a pipe and stopcock F to an air
exhausting pump worked by hand or otherwise so as to maintain a partial vacuum
throughout the apparatus which operates as follows.
The air pump connected at F so far rarefies the contents of B, that, if there
should be an absolute vacuum in A there is not sufficient excess of pressure in B to
overcome the column of mercury in the downward limb of E which consequently
acts as a seal.
The external mercury vessel is raised so that the mercury charges G and A and
just overflows into B. The vessel is then lowered and the mercury descends
from A and G leaving a torricellian vacuum in A and also in G until rarefied air
from V passes in G. When the mercury is again raised, the air is driven from G
into A and thence into B, and thus by alternately raising and lowering the mercury,
the contents of the vessels connected to V are more and more rarefied.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is :--
In a mercury vacuum pump, in combination with an exhausting pump and the
vacuum chamber G, the subsidiary chambers A and B and the siphon bends therein
arranged to operate instead of valves, substantially as described.
Dated this 26th day of August 1891.
ABEL & IMRAY,
Agents for the Applicant.