A New or Improved Pipette for Taking Up any Desired Quantity of Liquid.
Year: 1898

page_text: Date of Application, 1st July, 1898-Accepted, 3rd Sept., 1898
COMPLETE SPECIFICATION
A New or Improved Pipette for Taking Up any Desired Quantity of
Liquid.
I, PAUL WEISSGERBER, of Lanterbach, Upper Hesse, Germany, Government
Medical Officer, 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:-
A glass or metal tube, pointed at one end, but otherwise of equal diameter
throughout, (see drawing p), carries on the other end an india-rubber ball abc.
In this tube is a valve, the upper part of which, a stopper f, lies against the sides
of the tube so as to form an air-tight closing, and is perforated in the middle,
in the direction of the longitudinal axis. The lower part of the valve, a float h,
is composed of a pin-shaped part 9, which only partially fills the perforation in f,
in order that air may pass at the side, and carries a cross pin e which prevents
the float from dropping down. The lower part of the float h is hollow, and
formed of a material of very small specific gravity.
If the india-rubber ball be squeezed, the air will be forced through the perfora-
tion of the stopper f and press the float h so far under that ee will lie on ff. If
the ball be allowed to expand again, after pp has been submerged in a liquid,
the latter will rise only until the float h rises and rests closely against the under
surface of ff. The pipette when so filled, can be carried about, without any of
the liquid running out, and be emptied by one (a single) pressing of the ball.
If it be desired to discharge a large quantity of liquid, the stopper is drawn up
at dd, if a small quantity only, the stopper is pressed down lower.
In order to make the air-tight closing of the stopper opening through the float
more perfect, the contact surfaces can be formed as in Figs. 2, 3, and 4, and
covered with an india-rubber plate or leather.
The float must, in every direction, be so far apart from the sides of the pipette,
that more than a capillary space is left, as otherwise it may remain suspended
(hanging) a consequence of which would be a delay in the closing of the stopper,
or would prevent the closing of the stopper opening, and a rising of the liquid
above the stopper.
In order that the float may not more nearly approach the one side of the tube
than the other, it is furnished on the periphery with spacing or distance pins o,
in at least three places. In this way, is prevented from getting obliquely
placed in the perforation, whereby the friction would be increased and the rising
of the float made more difficult.
The pipette makes it possible to draw off and discharge a determined quantity
of liquid quickly and certainly, and allows of a better control of the same which
has hitherto not been possible in the apparatus used, in laboratories, and for the
oiling of bicycle wheels and other appliances.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
A pipette with a suction or pressure (air-ball) mounted thereon the characteristic

page_text: feature of which is a float valve g moveable in the pipette and furnished with
a piston f, that can be adjusted for a determined quantity of liquid to be taken
up by the pipette.
Dated this 1st day of July 1898.
HUGHES & YOUNG,
55 & 56, Chancery Lane, London, W.C., Agents for Applicant.