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

  • Donald, R.
Date:
[1913]
Catalogue details

Licence: In copyright

Credit: An apparatus for liquid measurement by drops and applications in counting bacteria and other cells and in serology, etc. / by R. Donald. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    tube, may be fitted on by a ferrule of washed rubber tubing or of good cork. A dropping-point to give watery drops of \ c.c. may be formed of tubing 14| mm. external diameter. The dropper is held in a stand at a height convenient to allow a rack of test-tubes to be slid under the dropping- point. The drop-rate may be regulated as desii'ed by fitting inside the dropping- tube, and within forceps-reach of the orifice, a throttle made of suitably drawn out capillary tube. The author has found the apparatus efficient in the following applications:— (1) Comparison of surface-tension of liquids, in quantity as little as \ c.c., e.y. in testing the value of the meiostagmin reaction in syphilis. (2) As the drop yielded by one pipette differs by not more than a fraction of 1 per cent, from the drop similarly yielded by another pipette similarly gauged in the same hole, the method may be used, with successive fresh pipettes, for rapidly and accurately measuring off small quantities of any liquid, from 0'25 c.c. to, say, 0 004 c.c, of watery liquids of high surface tension, or even smaller quantities of liquids of low surface tension, for instance, in:— (а) Measurements of various small quantities, in e.g. Wassermann reaction, micro-Wassermann re- action, and other complement-fixation tests; Widal reaction; alkalimetry, acidimetry, and other volu- metric tests ; testing cultures and disinfectants ; and Fig. 2. in pharmacy. (1) Direct estimation of cells, numerically, and roughly qualitatively, in small drops of cerebro-spinal fluid, dried on a slide. (c) Blood-count, red cells and white cells, from drops of diluted blood, similarly dried. {d) Direct counting of bacteria in small dried drops of diluted vaccines, distilled water, domestic water, sewage effluent, diluted milk. (б) , (c), and {d) yield permanent preparations. Harrison and Sons, Printers in Ordinary to His Majesty, St. Martin’s Lane.