IMPROVEMENTS IN MERCURIAL AIR-PUMPS
Year: 1883

page_text: LETTERS PATENT to Jerry Barrett of 15, Avenue Road, Regent's Park,
London, N.W. in the county of Middlesex, Artist for an Invention of
IMPROVEMENTS IN MERCURIAL AIR-PUMPS
.
PROVISIONAL SPECIFICATION left by the said Jerry Barrett at the Office
of the Commissioners of Patents on the 19th April 1883.
JERRY BARRETT of 15, Avenue Road, Regent's Park London, N.W. in the
county of Middlesex, Artist. IMPROVEMENTS IN MERCURIAL AIR-PUMPS
My improvements relate to mercurial air-pumps constructed on Poggendorff's
principle. The said principle involves the raising of a mass of mercury within a
closable system of vessels, and then the letting fall the said mass of mercury and
so as to leave in the vessels above it a vacuum.
My improvements consist partly in supplying mercurial air-pumps with valves the
parts of which do not retain particles of air or of gas or of vapour that should have free
passage through the said valves; and partly in so arranging the parts of a Mercurial
air-pump that an ordinary air-pump may be connected with it and may be used
when so connected and when desirable and before the mercurial air-pump has been
set in action to partially exhaust of air or of gas or of vapour a vessel that has
been suitably attached to the mercurial air-pump for exhaustion; and partially in
so forming and connecting and arranging certain of the vessels and tubes and
valves of a mercurial air-pump that they may when desirable be flooded with
sulphuric acid and may be used when so flooded with sulphuric acid for the
purposes for which they are formed and adapted as parts of a mercurial air-pump;
and partly in so constructing and adjusting a float-rod that a valve which is partly
formed by the said float-rod is opened and closed by the falling and by the rising
of mercury only when the chamber within which the said float-rod is partly situated
and within which a mass of falling mercury leaves a vacuum is quite empty of
mercury and thus ensuring that the said chamber shall only have connection
through the said valve with certain parts of the mercurial air-pump that are
situated above the said chamber when the said chamber is quite empty of mercury
and thus in the fullest possible manner attaining the special advantages yielded by
the use of a mass of mercury in an air-pump constructed on Poggendorff's

page_text: principle; and partly in so forming and arranging and connecting certain of the
vessels and tubes of a mercurial air-pump that the mercury and sulphuric acid
that are used in the mercurial air-pump are enclosed within the said vessels and
tubes during use and so that the said mercury and sulphuric acid are protected
from being contaminated by contact with atmospheric impurities and so that the
pump operators are not exposed to the deleterious action of mercurial vapours; and
partly in so forming and arranging and connecting the parts of a mercurial air-
pump constructed on Poggendorff's principle that the said mercurial air-pump may
be operated automatically by the reciprocal turning of a stopcock that is fitted at
the junction of three tubes that communicate respectively and through the said
stopcock with the mercury reservoir of the said mercurial air-pump and with an
ordinary air-pump that is being worked and with the atmosphere and so that the
reciprocal turning of the said stopcock shall make open connection between the
said mercury reservoir and an ordinary air-pump that is being worked and between
the said mercury reservoir and the atmosphere alternately; and partly in the con-
struction of apparatus by the use of which high vacua may be easily and rapidly
obtained in vessels such as are used for incandescent electric lamps and for other
purposes.
My improvements in mercurial air-pumps may be severally applied in the con-
struction of a mercurial air-pump as hereinafter described and as illustrated in the
drawing annexed hereto. Certain parts of the mercurial air-pump are severally
indicated by like letters of reference in the description and in the drawing.
There is a reservoir vessel A of the shape of an upright cylinder having closed ends
and having a capacity proportionate to the quantity of mercury that is designed to
be used in the mercurial air-pump. A tube P is connected with the upper part of the
vessel A and is fitted with an ordinary stop-cock W and is fitted with a stopcock e
that is constructed so as to permit open connection to be made between the
vessel A and an ordinary air-pump and alternately so as to permit open connection,
through an orifice in the stopcock e that is adjustable in size, to be made between
the vessel A and the atmosphere. There is an upright cylindrical vessel that
has a capacity slightly less than that of the vessel A and that has different
parts of different diameters and that has a vertical height of about thirty-two
inches. The lower part of the cylindrical vessel has the form of a tube R and
is placed inside the vessel A so that the lower end of the tube R is situated
about one eighth of an inch above the bottom of the vessel A. The tube R
and the vessel A are sealed hermetically together at their upper parts O. The
tube R has its lower end open and has such an internal diameter as will permit of
the free vertical motion of a float-rod K F Q Q₁ that is placed partly within it.
The upper part of the cylindrical vessel is divided, at a point that is preferably
about 26 inches above the lower end of the cylindrical vessel, into a small upper
chamber C and a larger lower chamber B by a constriction that forms an
internal annular shoulder M of such a diameter as to admit the passage of
the float-rod KF Q Q. The cylindrical vessel has a removable top T to
which it is sealed hermetically. A cup-funnel I that contains an hermetical
packing and forms a stuffing-box passes through and is sealed hermetically
to the top T of the cylindrical vessel. A tube J that has its upper end sealed
hermetically to the vessel E that is to be exhausted passes through the stuffing-
box I and has its lower end exposed openly within the upper part of the
chamber B. The stuffing-box I is so arranged that the tube J may have slight
movement vertically. The tube J is fitted near its lower end with a hollow
bulb G of regular form and of a diameter larger than that of the internal annular
shoulder M. The lower part of the tube J should have an internal diameter large
enough to ensure that drops of mercury and drops or films of sulphuric acid shall
not be upheld within it by capillary or contact attraction. The tube J near its
upper end has external connection with an adjustable spiral spring L that subjects
the tube J to slight vertical downwards pressure. A lever H is fitted so as to
have connection with the spring L. The The bulb G rests upon the internal

page_text: annular shoulder M. The shoulder M, the bulb G, the tube J, the hermetical'
packing inside the stuffing-box I and the spring L, in conjunction form a spring-
valve of special character that may be and is actuated by the pressure upwards
against the bulb G of mercury of acid or of air rising in the cylindrical vessel and
by pressing the handle of the lever H. Within the cylindrical vessel is placed a
float-rod K FQQ' of such length as to extend from the bottom of the vessel A
to about half an inch below the lower end of the tube J. The float-rod is formed
with two guides QQ¹ upon its lower part designed to keep it vertical in position
and is fitted with a float-bulb F near its middle and with an upright cup K at its
upper end. The inside part of the cup K and the lower end of the tube J are
fitted to one another so that when they are pressed together they form a closed
valve. The cup K may have any suitable cup form. Preferably the cup K has
interiorly in vertical section either a V-form or a W-form. In each case the lower
end of the tube J is correspondingly formed and fitted to the cup K. The lower
end of the tube J and the float-rod K F Q Q' and the cup K together form a valve
of special charater that may be and is actuated by the rising and by the falling
of mercury and of acid within the cylindrical vessel. The float-rod K F Q Q¹ is
adjusted by the size and relative height-position of its float-bulb and so as to float
upon and in the mercury and acid and so as to press upwards against the lower
end of the tube J so long as and no longer than mercury and acid remain in the
chamber B. A tube b one end of which is open in the upper part of chamber C
passes through and is sealed hermetically to the top T of the cylindrical vessel and
has connection through a stopcock a with a vessel D and through a chamber N
that is formed to hold air-drying and air-filtering substances such as anhydrous
phosphoric acid and cotton wool and through a stopcock Z with an ordinary air-
pump. A tube d one end of which is open in chamber C passes through and is
sealed hermetically to the top T of the cylindrical vessel, and is fitted with a
stopcock X and terminates in a funnel Y. When the vessel E that is to be
exhausted has to be kept stationary during the process of exhaustion the tube J
may and is to be bent at its upper part into a U or other shape (as at N) that
will permit the lower end of the tube J to have slight vertical movement whilst
the upper end of the tube J remains fixed. The tubes P and b after passing
the stopcocks Z and e unite and the union tube is connected with an ordinary
air-pump.
In the mercurial air-pump hereinbefore described all the vessels and the tubes
that connect them with one another are preferably to be made of glass; and the
tubes that connect the mercurial air-pump with an ordinary air-pump and the
stop cocks that are fitted on the said tubes may be made of non-corrodible metal;
and the float-rod may be made of platinum. The apparatus herein before described
having all its parts duly arranged and in working order and the vessel A having
been charged with a quantity of mercury sufficient to rather more than fill the
cylindrical vessel and with about one ounce of pure sulphuric acid and the
cylindrical vessel having been charged through the funnel Y with about one ounce
of pure sulphuric acid and a vessel E that is to be exhausted of air or of gas or of
vapour being suitably attached to the tube J and the stopcock X being closed and
the stopcocks Z and a and W being open and the stopcock e being turned so as to
make open connection between vessel A and the ordinary air-pump the said
apparatus may and is to be operated as follows.
First. The handle of the lever H is to be pressed and is to be retained under
pressure while the ordinary air-pump is being worked. A vacuum of the quality
best obtainable by means of the ordinary air-pump used having been produced in
vessels N and D and in chambers C and B and in vessel E and in the tubes
connecting them, the ordinary air-pump is to be disconnected with the mercurial
air-pump by closing the stopcocks Z and s and W and the handle of the lever H
is to be released from pressure. A vacuum of suitable quality is to be maintained
in vessels D and N and in chamber C and in the tubes connecting them during'
the time the apparatus is being used for the purpose of exhausting vessels. The

page_text: said permanent vacuum may be improved in quality when desirable and whilst
the spring valve is hermetically closed, by opening the stopcock Z whilst the
stopcock e is closed and by working the ordinary air-pump whilst it is so connected
with the permanent vacuum vessels.
Second. The stop cock W is to be opened and the stopcock e is to be turned so
as to make open connection between the vessel A and the atmosphere. The
atmosphere acting through the tube P and pressing upon the mercury in the
vessel A will cause the said mercury if it be not checked to rise in the cylindrical
vessel until the said mercury having risen past the bulb G reaches nearly to the
barometric height that obtains at the time and place of the operation. The actual
height that the column of mercury attains in the cylindrical vessel will partly
depend on the quality of the permanent vacuum that exists in chamber C and in
the parts of the apparatus that have open connection with chamber C. The mercury
and acid whilst rising in the cylindrical vessel uplift the float-rod K FQ Q₁ of
which action more hereinafter.
Third. The adjustable spring L may require adjustment and is to be adjusted to
the tension that will be suitable to the occasion and so that the said spring will
not act unduly as a check to the rising mercury or to any air or gas or vapour or
acid that the rising mercury may drive before it. The mercury and acid that rise
above the bulb G become trapped thereby and are prevented from falling by the
automatic action of the spring valve. The mercury and the sulphuric acid that the
action of the spring-valve traps above the bulb G act as an hermetical seal to the
said spring-valve. When desirable and when the permanent vacuum is of good
quality any portion or the whole of the mercury and of the sulphuric acid that have
become trapped above the bulb G may be released by pressing the handle of the
lever H and raising the bulb G slightly.
Fourth. The stopcock e is to be turned so as to make open connection between
the vessel A and the ordinary air-pump. The ordinary air-pump is now to be
worked. The action of the ordinary air-pump produces a vacuum in the vessel A
and the mercury in the cylindrical vessel falls by reason of its own weight and
flows from the cylindrical vessel into the vessel A. The mercury that falls in the
cylindrical vessel leaves behind and above itself and in the chamber B and below
the hermetically sealed spring-valve, a vacuum. Soon after the chamber B has
become empty of mercury and of sulphuric acid the float-rod K F Q Q¹ drops untill
the cup K. falls clear away from the lower end of the tube J. This opening of the
float-valve makes open connection through the tube J between the chamber B and
the vessel E that is to be exhausted. Within a minutes' time after the opening of
the float-valve the residual air and gas and vapour that the vessel E and the tube J
contain diffuse into the chamber B.
Fifth. The stopcock e is now to be turned so as to make open connection between
the vessel A and the atmosphere. The atmosphere acting through the tube P and
pressing upon the mercury and acid that are in the vessel A will cause them to
rise in the cylindrical vessel. The mercury and acid whilst rising in the cylindrical
vessel and before entering the chamber B lift the float-rod K F QQ' and cause the
cup K to close up against the lower end of the tube J. The portion of mercury
and acid that during the herein before described fourth stage of working the
apparatus was left in the cup K and that continues to be upheld by the cup K
seals hermetically the float-valve directly the cup K closes up against the lower
end of the tube J. By the closure of the float-valve the residual air and gas and
vapour that passed from the vessel E and the tube J into the chamber B during
the hereinbefore described fourth stage of working the apparatus becomes trapped
in the chamber B. The mercury and acid whilst rising gradually in the chamber B
drive the therein trapped air and gas and vapour upwards and past the bulb G
into chamber C. From chamber C the ejected air and gas and vapour diffuse in
the vessels D and N and in their connecting tubes and deteriorate slightly the
quality of the permanent vacuum therein contained.
When the herein before described first and second and third stages of working.
1.

page_text: the apparatus have duly been carried out the hereinbefore described fourth and
fifth stages of working the apparatus are to be repeated alternately as many times
as may be necessary to obtain a vacuum in the vessel E of the quality desired.
When the cylindrical vessel is to be flooded with sulphuric acid the acid is to be
poured through the tube d. The acid may be withdrawn by suction from the
chamber C through the tube d and into a Woulff's bottle that has been connected
with the tube d.
The rapidity with which the apparatus herein before described may be made to
exhaust of air or of gas or of vapour any vessel E largely depends on the relative
capacities of the vessel E and of the chamber B. The larger the chamber B is
relatively to the vessel E the greater will be the rapidity with which the vessel E
may be exhausted. For general purposes chamber B may have a capacity two
hundred times greater than the capacity of the vessel E. For special purposes
chamber B may have a capacity as many times greater than the capacity of the
vessel E as especial circumstances may indicate to be desirable.
In the event of several mercurial air-pumps constructed as hereinbefore described
being used in circuit and in connection with an ordinary air-pump and in connection
with an ordinary motor engine the stopcock W may be used to disconnect any one
mercurial air-pump with the said circuit without affecting the action of the
other mercurial air-pumps that are in the said circuit and without the motor engine
being stopped.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent bied by
the said Jerry Barrett in the Great Seal Patent Office on the 11th October
1883.
JERRY BARRETT of 15 Avenue Road Regents Park London N.W. in the
County of Middlesex Artist "IMPROVEMENTS IN MERCURIAL AIR-PUMPS "
My improvements relate to mercurial air-pumps constructed on Poggendorff's
principle. The said principle involves the raising of a mass of mercury within a
closable system of vessels and then the letting fall the said mass of mercury and so
as to leave in the vessels above it a vacuum. My improvements consist partly in
supplying mercurial air-pumps with valves the parts of which do not retain particles
of air or of gas or of vapour that should have free passage through the said valves;
and partly in so arranging the parts of a mercurial air-pump that an ordinary air-
pump may be connected with it and may be used when so connected and when
desirable and before the mercurial air-pump has been set in action to partially
exhaust of air or of gas or of vapour a vessel that has been suitably attached to
the mercurial air-pump for exhaustion; and partly in so forming and connecting
and arranging certain of the vessels and tubes and valves of a mercurial air-punip
that they may when desirable be flooded with sulphuric acid and may be used
when so flooded for the purposes for which they are formed and adapted as parts
of a mercurial air-pump; and partly in so constructing and adjusting a float-rod
that a valve which is partly formed by the said float-road is opened and closed by
the falling and by the rising of mercury only when the chamber within which the
said float-rod is partly situated and within which a mass of falling mercury leaves
a vacuum is quite empty of mercury and thus ensuring that the said chamber shall
only have connection through the said valve with certain parts of the mercurial
air-pump that are situated above the said Chamber when the said chamber is quite
empty of mercury and thus in the fullest possible manner attaining the special
advantages yielded by the use of a mass of mercury in an air-pump constructed
on Poggendorff's principle; and partly in so forming and arranging and connecting
certain of the vessels and tubes of a mercurial air-pump that the mercury and
sulphuric acid that are used in the said mercurial air-pump are enclosed within the
said vessels and tubes during use and so that the said mercury and sulphuric acid
are protected from being contaminated by contact with atmospheric impurities and
so that the pump operators are not exposed to the deleterious action of mercurial
vapour; and partly in so forming and arranging and connecting the parts of a
mercurial air pump constructed on Poggendorff's principle that the said mercurial
air-pump may be operated automatically by the reciprocal turning of a stop-cock
that is fitted at the junction of three tubes that communicate respectively and
through the said stop-cock with the mercury reservoir of the said mercurial air-
pump, and with an ordinary air-pump that is being worked and with the
atmosphere and so that the reciprocal turning of the said stop cock shall make
open communication between the said mercury reservoir and an ordinary air pump
that is being worked, and between the said mercury reservoir and the atmosphere,
alternately; and partly in the construction of apparatus by the use of which vacua
may be rapidly obtained in vessels such as are used for incandescent electric lamps
and for other purposes.
My improvements in mercurial air-pumps may be severally applied in the
construction of a mercurial air-pump as hereinafter described and as illustrated in
the drawing annexed hereto. Certain parts of the mercurial air-pump are
severally indicated by like letters of reference in the description and in the
drawing

page_text: There is a reservoir vessel A of the shape of an upright cylinder having closed
ends and having a capacity proportionate to the quantity of mercury that is
designed to be used in the mercurial air pump. A tube P is connected with the
upper part of vessel A and is fitted with an ordinary stop-cock W and is fitted
with a stop-cock e that is constructed so as to permit open communication to be
made between vessel A and an ordinary air-pump and alternatively so as to permit
open communication through an orifice in stop-cock e that is adjustable in size, to
be made between vessel A and the atmosphere. There is an upright cylindrical
vessel that has a capacity slightly less than that of vessel A and that has different
parts of different diameters and that has a vertical height of about thirty two
inches. The lower part of the cylindrical vessel has the form of a tube R and is
placed inside vessel A so that the lower end of tube R is situated about one
eighth of an inch above the bottom of vessel A.
The tube R and vessel A are sealed hermetically together at their upper parts O.
The tube R has its lower end open and has such an internal diameter as will permit
of the free vertical motion of a float-rod K. F. Q. Q¹ that is placed partly within it.
The upper part of the cylindrical vessel is divided at a point that is preferably about
twenty six inches above the lower end of the cylindrical vessel into a small upper
chamber C and a larger lower chamber B by a constriction that forms an internal
annular shoulder M of such a diameter as to admit the passage of the float-rod
K. F. QQ. The cylindrical vessel has a removable top T to which it is sealed
hermetically. A cup-funnel I that contains an hermetical packing and forms a
stuffing-box passes through and is sealed hermetically to the top T of the cylindrical
vessel. A tube J has its upper end sealed hermetically, to the vessel E that is to be
exhausted and passes through the stuffing-box I and has its lower end exposed
openly in the upper part of the chamber B. The stuffing-box I is so arranged that
tube J may have slight movement vertically. The tube J is fitted near its lower
end with a hollow bulb G of regular form and of a diameter larger than that of
the internal annular shoulder M. The hollow bulb G and the lower part of the
tube J should have internal diameters large enough to ensure that drops of mercury
and drops or films of sulphuric acid shall not be upheld within them by capillary or
contact attraction. The tube J near its upper end has external connection with an
adjustable spiral spring L that subjects tube J to slight vertical downwards
pressure. A lever H is fitted so as to have connection with the spring L. The
bulb G rests upon the internal annular shoulder M. The shoulder M, the bulb G,
the tube J, the hermetical packing inside the stuffing-box I, and the spring L
constitute and form a spring valve of special character that may be and is actuated
by the pressure upwards against the bulb G of mercury or of acid, or of air
rising in the cylindrical vessel and by pressing the handle of the lever H.
Within the cylindrical vessel is placed a float-rod K. F. Q. Q of such length
as to extend from the bottom of vessel A to about half an inch below the lower end
of tube J. The float rod is formed with two guides Q Q' upon its lower part designed
to keep it vertical in position and is fitted with a float-bulb F near its middle and
with an upright cup K at its upper end. The inside part of the cup K and the
lower end of tube J are fitted to one another so that when they are pressed together
they form a closed valve. The cup K may have any suitable cup form. Preferably
the cup K has interiorly in vertical section either a V form or a W form.
In each case the lower end of the tube J is correspondingly formed and
fitted to the cup K. The lower end of tube J and the float-rod K. F. Q. Q¹ and
the cup K constitute and form a valve of special character that may be and is
actuated by the rising and by the falling of mercury and of acid in the cylindrical
vessel. The float rod K. F. Q. Q' is adjusted by the size and relative height-position
of its float-bulb and so as to float upon and in the mercury and acid and so as to
press upwards firmly against the lower end of tube J so long as and no longer than
mercury and acid remain in chamber B. A tube 6 passes from the upper part of
chamber Cand has connection through a stop-cock a with a vessel D and through a
chamber N that is formed to hold air-drying and air-filtering substances such as

page_text: anhydrous phosphoric acid and cotton-wool and through a stop-cock Z with an
ordinary air-pump. A tube d one end of which is open in chamber C passes
through and is sealed hermetically to the top T of the cylindrical vessel and is
fitted with a stop-cock X and terminates in a funnel Y. When the vessel E that
has to be exhausted has to be kept stationary during the process of exhaustion
tube J may and is to be bent at its upper part into a U or other shape (as at N¹)
that will permit the lower end of the tube J to have slight vertical movement
whilst the upper end of tube J remains fixed. The tubes P and b after passing
the stop-cocks Z and e unite and the union tube g is connected with an ordinary
air pump. In the mercurial air-pump herein before described all the vessels and
the tubes that connect them with one another are preferably to be made of glass
and the tubes that connect the mercurial air-pump with an ordinary air-pump and
the stop-cocks that are fitted on the said tubes may be made of non-corrodible
metal and the float-rod may be made partly of platinum and partly of glass.
The apparatus herein before described having all its parts duly arranged and in
working order and vessel A having been charged with a quantity of mercury
sufficient to rather more than fill the cylindrical vessel and with about one
ounce of pure sulphuric acid and the cylindrical vessel having been charged
through funnel Y with about one ounce of pure sulphuric acid and a vessel E that
is to be exhausted of air or of gas or of vapour being suitably attached to
tube J and stop-cock X being closed and stop-cocks Z and a and W being
open and stop-cock e being turned so as to make open communication between
vessel A and the ordinary air pump, the said apparatus may and is to be operated
as follows:
First. The handle of the lever H is to be pressed and is to be retained under
pressure while the ordinary air-pump is being worked. A vacuum of the quality
best obtainable by means of the ordinary air-pump used having been produced in
vessels N and D and in chambers C and B and in vessel E and in the tubes
connecting them, the ordinary air-pump is to be disconnected with the mercurial
air-pump by closing stop-cocks Z and e and W and the handle of the lever H is to
be released from pressure. A vacuum of suitable quality is to be maintained
in vessels D and N and in chamber C and in the tubes connecting them during
the time the apparatus is being used for the purpose of exhausting vessels.
The said permanent vacuum may be improved in quality when desirable and whilst
the spring valve is hermetically closed by opening stop-cock Z whilst stop-cock e is
closed and by working the ordinary air-pump whilst it is so connected with the
permanent vacuum vessels.
Second. The stop-cock W is to be opened and stop-cock e is to be turned so as
to make open communication between vessel A and the atmosphere. The
atmosphere acting through tube P and pressing upon the mercury in vessel A will
cause the said mercury, if it be not checked, to rise in the cylindrical vessel until
the said mercury having risen past the bulb G reaches nearly to the barometric
height that obtains at the time and place of the operation. The actual height
that the column of mercury attains in the cylindrical vessel will partly depend on
the quality of the permanent vacuum that exists in chamber C and in the parts of
the apparatus that have open communication with chamber C The mercury and
acid whilst rising in the cylindrical vessel uplift the float-rod K. F. Q. Q¹, of which
action more hereinafter.
Third. The adjustable spring may require adjustment and is to be adjusted to
the tension that will be suitable to the occasion and so that the said spring will
not act unduly as a check to the rising mercury or to any air or gas or vapour or
acid that the rising mercury may drive before it. The mercury and acid that rise
above bulb G become trapped thereby and are prevented from falling by the
automatic action of the spring valve. The mercury and the acid that the action
of the spring valve traps above the bulb G act as an hermetical seal to the said
spring valve. When desirable and when the permanent vacuum is of good quality
any portion or the whole of the mercury and of the acid that have become trapped

page_text: above the bulb G may be released by pressing the handle of lever H and so raising
bulb G slightly.
Fourth. The stop-cock e is to be turned so as to make open communication
between vessel A and the ordinary air-pump. The ordinary air-pump is now to
be worked. The action of the ordinary air-pump produces a vacuum in vessel A
and the mercury in the cylindrical vessel falls by reason of its own weight and
flows from the cylindrical vessel into vessel A. The mercury that falls in the
cylindrical vessel leaves behind and above itself and in the chamber B and below
the hermetically sealed spring valve, a vacuum. Soon after chamber B has become
empty of mercury and of acid the float rod K. F. Q. Q. drops until the cup K falls
clear away from the lower end of tube J. This opening of the float-valve makes
open communication through tube J between chamber B and the vessel E that is
to be exhausted. Within a minutes' time after the opening of the float valve the
residual air and gas and vapour that vessel E and tube J contain diffuse into
chamber. B.
Fifth. The stop-cock e is now to be turned so as to make open communication
between vessel A and the atmosphere. The atmosphere acting through tube P
and pressing on the mercury and acid that are in vessel A will cause them to rise
in the cylindrical vessel. The mercury and acid whilst rising in the cylindrical
vessel and before entering chamber B lift the float-rod K. F. Q. Q and cause the
cup K to close up against the lower end of tube J. The portion of mercury and
acid that during the herein before described fourth stage of working the apparatus
was left in the cup K and that continues to be upheld by the cup K seals
hermetically the float valve, directly the cup K closes up against the lower end of
tube J. By the closure of the float valve the residual air and gas and vapour that
passed from vessel E and tube J into chamber B during the hereinbefore described
fourth stage of working the apparatus become trapped in chamber B. The mercury,
and acid whilst rising gradually in chamber B drive the therein trapped air and
gas and vapour upwards and past bulb G into chamber C. From chamber C the
ejected air and gas and vapour diffuse into vessels D and N and into their
connecting tubes and deteriorate slightly the quality of the permanent vacuum
therein contained.
When the hereinbefore described first and second and third stages of working
the apparatus have duly been carried out, the hereinbefore described fourth and
fifth stages of working the apparatus are to be repeated alternately, as many
times as may be necessary to obtain a vacuum in vessel E of the quality
desired.
When the cylindrical vessel is to be flooded with sulphuric acid the acid is to
be poured through tube d. The acid may be withdrawn by suction from
chamber C through tube d and into a Woulff's bottle that has been connected with
tube d.
The rapidity with which the apparatus hereinbefore described may be made to
exhaust of air or of gas or of vapour any vessel E largely depends on the relative
capacities of vessel E and of chamber B. The larger chamber B is relatively to
vessel E the greater will be the rapidity with which vessel E may be exhausted.
For maximum economy of materials in construction chamber B should have a
capicity ten times greater than that of vessel E For special purposes chamber B
may have a capacity as many times greater than that of vessel E as special
circumstances may indicate to be desirable.
In the event of several mercurial air-pumps constructed as herein before described
being used in circuit and in connection with a motor engine, the stop-cock W may
be used to disconnect any one mercurial air-pump with the said circuit without
affecting the action of the other mercurial air pumps that are in the said circuit
and without the motor engine being stopped
Having hereinbefore particularly described and ascertained the nature of my
said Invention and in what manner the same is to be performed.

page_text: I claim as the invention that is secured to me by the hereinbefore in part recited
Letters Patent.-
First. Apparatus formed and arranged substantially as hereinbefore described
and as illustrated in the drawing annexed hereto and constituting a mercurial air
pump.
Second. An adjustable spring valve that is constructed with and has as chief
parts a tube placed vertically and an adjustable spring that has connection
externally with the said tube near its upper end and a stuffing-box through which
the said tube passes and may have motion and an hermetical packing inside the
said stuffing-box and a bulb that is fitted symmetrically around and upon the said
tube near its lower end and a vessel that has an internal annular shoulder upon
which the said bulb rests and formed and arranged substantially as hereinbefore
described and as illustrated in the drawing annexed hereto.
Third. A valve that is constructed with a tube placed vertically and having its
lower end open and with a rod that has fitted to it near its mid-length-point a
float and at its upper end an upright cup the inside of which is fitted to close
tightly up against the end of the said open tube and formed and arranged
substantially as herein before described and as illustrated in the drawing annexed
hereto.
Fourth. In mercurial air-pumps the formation and arrangement of parts sub-
stantially as hereinbefore described and as illustrated in the drawing annexed
hereto that enables the diffusion chamber B to have a capacity many times larger
than that of the vessels in which high vacua are usually required.
Fifth In mercurial air-pumps the formation and arrangement of parts sub-
stantially as hereinbefore described and as illustrated in the drawing annexed
hereto that enables the vessel that has to be exhausted of air, &, after it has been
duly connected with the mercurial air pump to be to a certain degree exhausted
of air, &, through the mercurial air pump by the action of an ordinary air pump
that has been duly connected with the mercurial air-pump.
Sixth-In mercurial air pumps the formation and arrangement of parts sub-
stantially as herein before described and as illustrated in the drawing annexed
hereto that enables the mercurial air pump when it is duly connected with an
ordinary air pump to be operated by the action of a motor engine that has been
duly connected with the mercurial air-pump and with the said ordinary air-pump.
Seventh. In mercurial air pumps the formation and arrangement of parts sub-
stantially as hereinbefore described and as illustrated in the drawing annexed
hereto that enables certain parts of the mercurial air pump to be flooded with
sulphuric acid and to be used when so flooded for the purposes for which they have
been formed and adapted as parts of a mercurial air-pump and without the said
acid having self vitiating contact with the outer air
In witness whereof I the said Jerry Barrett have hereunto set my hand and
seal this ninth day of October One thousand eight hundred and eighty three.