IMPROVEMENTS IN APPARATUS FOR PRODUCING HIGH VACUUM
Year: 1882

page_text: LETTERS PATENT to John Jameson, of Akenside Hill in the City of Newcastle-
upon-Tyne, Consulting Engineer for an Invention of IMPROVEMENTS IN
APPARATUS FOR PRODUCING HIGH VACUUM.
PROVISIONAL SPECIFICATION left by the said John Jameson at the Office
of the Commissioners of Patents on the 1st September 1882.
JOHN JAMESON of Akenside Hill, in the City of Newcastle upon Tyne.-
Consulting Engineer IMPROVEMENTS IN APPARATUS FOR PRODUCING HIGH
VACUUM.
I employ by preference mercury or oil of vitriol or both as the lute whereby the
part of the apparatus in which the highest vacuum is produced is seperated from a
part wherein a less vacuum is maintained as is well understood, but instead of
using a fall of mercury as in the Sprengle pump to carry minute portions of air or
gas with it, and instead of repeatedly exhausting a reservoir by what is known as
the Torricillian vacuum as is also sometimes done I employ an open bottomed
vessel or vessels which may be elevated above the level of the mercury in the
highest vacuum chamber, and again depressed below the surface of this mercury so
as alternately to become filled with the highly rarified atmosphere of the nearly
vacuous chamber and with mercury, and I provide a passage or passages whereby
the portion of air so enclosed in this vessel and condensed by the immersion of the
vessel below the mercury may be pressed out of the vessel into a receptacle provided
for it whence it may be extracted by means of an air pump or otherwise and in
order to provide against entanglement of air in any film which might form on the
surface of the mercury and which might so become adherent to the sides of the
vessel I have referred to as entering the vacuum chamber I use a layer or filmn of
strong sulphuric acid over the top of the mercury in the vacuous chamber so as to
wash with absolute contact the inner surface of my receiving vessel and to saturate
any accidentally adherent film.-A part of this vitriol I pass at each stroke from
the vacuous chamber along with any contained air into the receptacle I have
described so as to make sure that all the contained air of the moving vessel is passed
[Price 6dI

page_text: out and I must then provide a means whereby a supply of vitriol is given to the
vacuous chamber or whereby what may be passed away each stroke is passed back.―
I prefer the latter alternative and provide means whereby a certain adequate portion
of vitriol is passed back periodically.
The arrangement of apparatus according to my invention may vary considerably
in detail. The vessel or vessels alternately passed into the vacuous chamber and
dipped below the mercury may be mounted upon the periphery of a wheel for
instance or they may be at one end of a rough bar and they may be actuated in
various ways. I prefer the weigh bar arrangement in carrying but which I use a
vacuous chamber or chambers of glass, platinum, or other convenient material and
a glass or platinum vessel or vessels nearly fitting to the vacuous chamber, when
elevated to its highest point.-I provide an air tight dividing plate so as to seperate
the high vacuum chamber from a chamber not so highly vacuous which plate dips
under the mercury common to the lower part of both chambers to the requisite
degree. I provide a tube or tubes leading from the top of the vessel or vessels
before referred to under the diaphragm or dividing plate so as that in all positions
of the weighbar its open end is under mercury and I provide mechanism to oscillate
the weighbar. The tube or tubes I so arrange as that any portion of air contained
within the vessel or vessels I have described shall on its attaining its lowest position
have a free passage inclining upwards at all points and ending without the
diaphragm bounding the vacuous chamber. I provide also a reserve apparatus of a
smaller size but preferably working stroke for stroke with the other on the same
weigh bar so as to return vitriol into the highly vacuous chamber so regulating the
proportion of vitriol as that in no circumstances can air be returned.
By these means I obtain extreme exhaustion with great rapidity and with an
expenditure of power approximately in proportion to the work done instead of
largely in excess as by the usual methods.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Jameson in the Great Seal Patent Office on the 27th February
1883.
JOHN JAMESON of Akenside Hill in the City of Newcastle-upon-Tyne,
Consulting Engineer.-IMPROVEMENTS IN APPARATUS FOR PRODUCING HIGH
VACUUM.
I employ by preference mercury or oil of vitriol or both as the lute whereby the
part of the apparatus in which the highest vacuum is produced is separated from a
part wherein a less vacuum is maintained as is well understood but instead of
using a fall of mercury as in the Sprengle pump to carry minute portions of air or
gas with it, and instead of repeatedly exhausting a reservoir by what is known as
the Torricillian vacuum as is also sometimes done I employ an open bottomed
vessel or vessels which may be elevated above the level of the mercury in the
bighest vacuum chamber, and again depressed below the surface of this mercury so
as alternately to become filled with the highly rarified atmosphere of the nearly
vacuous chamber and with mercury; and I provide a passage or passages whereby
the portion of air so enclosed in this vessel and condensed by the immersion of the
vessel below the mercury may be pressed out of the vessel into a receptacle
provided for it whence it may be extracted by means of an air pump or otherwise
and in order to provide against entanglement of air in any film which might form
on the surface of the mercury and which might so become adherent to the sides of
the vessel I have referred to as entering the vacuum chamber I use a layer or film
of strong sulphuric acid over the top of the mercury in the vacuous chamber so as
to wash with absolute contact the inner surface of my receiving vessel and to
saturate any accidentally adherent film.-A part of this vitriol I pass at each stroke
from the vacuous chamber along with any contained air into the receptacle I have
described so as to make sure that all the contained air of the moving vessel is
passed out and I must then provide a means whereby a supply of vitriol is given
to the vacuous chamber or whereby what may be passed away each stroke is
passed back. I prefer the latter alternative and provide means whereby a certain
adequate portion of vitriol is passed back periodically.-The arrangement of
apparatus according to my Invention may vary considerably in detail.-The vessels
or vessels alternately passed into the vacuous chamber and dipped below the
mercury may be mounted upon the periphery of a wheel for instance or they may
be at one end of a weigh bar and they may be actuated in various ways.-I prefer
the weighbar arrangement in carrying out, which I use a vacuous chamber or
chambers of glass, platinum, or other convenient material and a glass or platinum
vessel or vessels nearly fitting to the vacuous chamber when elevated to its highest
point. I provide an air tight dividing plate so as to seperate the high vacuum
chamber from a chamber not so highly vacuous which plate dips under the mercury
common to the lower part of both chambers, to the requisite degree.-I provide a
tube or tubes leading from the top of the vessel or vessels before referred to under
the diaphragm or dividing plate so as that in all positions of the weighbar its open
end is under mercury and I provide mechanism to oscillate the weighbar. The
tube or tubes I so arrange as that any portion of air contained within the
vessel or vessels I have described shall on its attaining its lowest position have a
free passage inclining upwards at all points and ending without the diaphragm
bounding the vacuous chamber.-I provide also a reverse apparatus of a smaller
size but preferably working stroke for stroke with the other on the same weigh bar
Bo as to return vitriol into the highly vacuous chamber so regulating the proportion

page_text: of vitriol as that in no circumstances can air be returned.-By these means I
obtain extreme exhaustion with great rapidity and with an expenditure of power
approximately in proportion to the work done instead of largely in excess as by the
usual methods.
Having thus described the nature of my Invention I will for greater clearness
proceed to describe a form of apparatus for operating the same reference being had
to the drawing hereto attached.
A. B. C. Fig. 1, Fig. 2, and Fig. 3 is a section of. a. vessel containing mercury.
The shape of this vessel should be made with corners rounded off and unnecessary
spaces filled up so as to economise mercury and also to diminish cushion space in
the vacuous chamber or chambers, but for the sake of clearness I have shewn the
receptacle square cornered.-The level of the mercury when under high exhaustion
is indicated by the heavily shaded lines within this vessel and the dotted
lines L. M. and the level of a supply of oil of vitriol or other convenient medium
for discharging the air, is shewn by the more lightly shaded lines within the
vessel and the dotted lines O. P.-B is the chamber of highest vacuum; A. that of
less vacuum which is in communication through the barometer tube J. dipping
into a mercury lute Q. with an air pump attached to K. capable of producing a
good vacuum.-R. is a dividing plate between the chambers A and B. so arranged
as that if any leakage should occur by the stuffing box which may be used on the
weigh bar W. it may pass into the chamber A. instead of the chamber B. In this
dividing plate there is an opening so as that on the first exhaustion of the apparatus
by means of the air pump the level of the mercury and vitriol in B. may not be
too much depressed but this opening must be in all cases below the level to which
by the working of the apparatus itself the mercury in A. may be depressed. W, is
a weigh bar carrying the vessel D and the vessel E. and placing them alternately
in the position shewn respectively in Figs. 1 and 2. The vessel D ends in the
tube d, and the vessel E in the tube e; there is however no communication
between the vessel and tube D, d, and the vessel and tube E. e, altho both are
mounted on the same weighbar and oscillate simultaneously.-I is the connecting
pipe to the vessel which it is desired to exhaust, the attachment being of any
convenient form and luted in any convenient usual way. In the working of the
apparatus the air pump is first employed and as the chamber A. becomes exhausted
the level of the mercury in the chamber B. becomes lowered until it falls to the
opening before referred to in the dividing plate.-If it be desired to economise the
work of the special exhausting arrangements, a second barometer tube may be used
in the chamber B. similar to that in the chamber A. with a similar lute Q. and the
pump may be applied to both tubes simultaneously, the effect of which would be
to carry the vacuum in the chamber B in the first instance to a higher point than
it could be carried by the more simple way of operating which for clearness I
describe, but as this is not a matter in any way affecting the principle of my
invention I have not shewn it in the drawing. When the mercury in B. is
depressed by the pressure above it to the level of the opening of the dividing plate
the vitriol will pass through into the chamber A. and thereafter air will pass until
equilibrium be established or nearly so between the chamber B. and the air pump,
the vacuum in B corresponding to that in the latter minus the pressure due to the
depth of the lutes of mercury and vitriol in A. above the orifice in the dividing
plate and in Q, above the level of the pipe bottom and the degree of pressure
necessary to operate the valves of the air pump if such valves be used and no
further vacuum can then be obtained by further pumping, but by the oscillation of
the weigh bar which may then be commenced the vessel D is alternately made to
ascend into the vacuous chamber B and descend below the mercury so as that a
portion of any gas or air contained in B may be caught in the vessel D. and being
thus retained in it as it dips below the mercury it will pass up the pipe d, and by
repeated movements further exhaustion in the vessel B. is thus produced until the
level of the mercury is raised in the chamber B above the level of that in
chamber A. representing a correspondingly higher degree of exhaustion.-In order

page_text: more effectually to sweep out the gaseous contents of the vessel D, at each
depression I prefer to have on the top of the mercury a layer of oil of vitriol or
other convenient medium a portion of which is at each stroke caught within the
vessel D, and floating on the mercury, washes the interior of that vessel as it alters
its position and finally washes the pipe d, carrying with it any contained air and
passing a portion of the vitriol at each stroke into the vessel A. The vessel E.
being a smaller vessel than D. by its oscillation catches a certain portion of the
vitriol only in A. and not the air, and returns it by the pipe, e, into the chamber B.
The level of the vitriol in A is such as that the vessel E can never rise above it
and in order to avoid the passage backwards and forwards of too much vitriol
which would involve a needless expenditure of power I make the size of the
vessel E, small relatively to the vessel D, and I may also make the position of the
vessels on the weigh bar adjustable in reference to each other.-It will be evident
that in this arrangement altho' the vessel D. may be apparently filled with the
attenuated gas or air each time it enters the chamber B. yet as it dips below the
mercury the power required to depress it will not be represented by the ratio of
the specific gravity of the vessel so apparently filled and an equal bulk of mercury
because the attenuated gas will be compressed before the mercury and mercury
will occupy a considerable portion of the space before any passage occurs to the
vessel A. so that the actual power expended will correspond very nearly with the
actual work done, and I wish also to point out that altho' it might appear as if on
the ascent of the vessel D. it would be heavily weighted by mercury as it emerged
from the bath at the level of the surface of the mercury in B. it would not be
really so weighted excepting by a film corresponding to the difference in the level
of the mercury between perfect vacuum and the vacuum in B. and the same remark
applies to the vessel E. and the vacuum in A. so that saving for the power required
to convey the small quantity of vitriol required from chamber to chamber and the
friction of the mechanism, the work of the whole apparatus corresponds nearly to
the actual work done instead of as with various other high vacuum pumps to a
very much larger amount of power; and while the rapidity of the action is
considerable the vacuum attained may be carried to the very highest point. The
stuffing box of the weighbar may be luted with mercury.
In Witness whereof I the said John Jameson, have hereunto set my hand
and seal this twenty second day of February one thousand eight hundred
and eighty three.
Witness
JOHN BOWMER
Clerk
Forest Hall
J JAMESON (L.S.)
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