An apparatus for the measurement of small quantities of fluid / by J.W. Trevan.

  • Trevan, J. W. (John William)
Date:
[1922?]
Catalogue details

Licence: In copyright

Credit: An apparatus for the measurement of small quantities of fluid / by J.W. Trevan. Source: Wellcome Collection.

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    AN APPARATUS FOR THE MEASUREMENT OF SMALL QUANTITIES OF FLUID.1 By J. W. TREVAN, M.B., B.S.Lond., WELLCOME PHYSIOLOGICAL RESEARCH LABORATORIES. This apparatus for measuring volumes of fluid from 0-5 c.cm. to 0-005 c.cm., with an accuracy of 1 per cent., was designed to measure 0-02 c.cm. of diphtheria toxin into capillary tubes for the per¬ formance of the Schick test, but can be used for any titration which involves the making of high dilu¬ tions—e.g., the Wassermann or other serological reactions. It consists of a good 1 c.cm. syringe (all-glass “ tuberculin ” or record) and an engineering micro¬ meter head, clamped in line by brass clamps to a \ inch steel rod. The micrometer head is graduated in one-hundredths of a millimetre ; its motion pushes the piston of the syringe, and the fluid to be measured is delivered through a steel (preferably rustless) needle under the surface of the diluent (to avoid drop errors). The knob on the piston is either ground plane or drawn out to a rounded point. The instrument can be calibrated roughly by measuring the distance between the marks on the syringe and calculating the volume corresponding to 1/100 mm. (=1/50 of a turn of the head of the micrometer), or by weighing mercury delivered. The piston must be thoroughly wetted with the fluid to be used before setting up. The usual micro¬ meter found in most laboratories can be used if a copper trough is made and arranged so that the anvil of the micrometer fits into the hollow of the trough, one end of which clips on to the knob of the piston, and the other is closed by a flat plate on which the plunger of the micrometer works. 1 Shown at the Pathological Section of the Royal Society of Medicine, Feb. 21st, 1922.