An apparatus for liquid measurement by drops and applications in counting bacteria and other cells and in serology, etc

Abstract

To promote drop-measuring in serological and bacteriological work, etc., the writer has devised a simple system of producing uniform pipettes, clean and sterile, which deliver uniform drops of any required size from ¼ c. c. down to 1/200 c. c. or less, and has devised also simple forms of constant-pressure apparatus for use with the pipettes. The fundamental principle of his method rests on the fact that the size of a drop of a given liquid yielded by a clean pipette is determined by the outer circumference of the pipette at the level where the contact-edge of the drop clings round the glass—due allowance being made for the rate at which the drop is detached and the temperature.