A method of titrating physiological fluids / by G.S. Walpole.

  • Walpole, George Stanley.
Date:
1910
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: A method of titrating physiological fluids / by G.S. Walpole. 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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    Journal Physiology ^)rol. XL. [From the Proceedings of the Physiologicto,? Society, March lfy' 1910.] A method of titrating physiological fluids. By G. S. Walpole. In the process of titration the “end-point” is, theoretically speaking, a certain definite H- or OH' ionic concentration. In practice an indicator is used to visualise this. When dealing with colourless solutions of well-dissociated acids and bases the change of H- ionic concentration as the neutralising solutions are mixed is rapid and the use of an indicator presents no difficulty. Physiologists, however, are frequently called upon to titrate fluids which are coloured and contain feebly dissociated materials. A method of doing this is given by S. P. L. Sorensen1 in his excellent survey of this problem. He has gone into the subject thoroughly and has prepared a number of standard mixtures the H‘ ionic concentration, and therefore also the OH' ionic concentration, of which he has carefully measured by use of a hydrogen electrode. He recommends for general use, the comparison of the solution to be titrated with one of his standard mixtures, using the same indicator in each case and compensating for the colour of the fluid investigated by means of certain neutral dyes. The modification of this method here proposed necessitates the use of a homely apparatus hut does away with the tedium of matching the colours of the untitrated fluids and with the use of neutral dyes altogether. A second sample of the same fluid compensates for the colour of the solution to he titrated. The “ end-point ” of the titration is, as before, that correponding to the H' concentration of a suitable mixture taken from Sorensen’s tables. Two similar glass cells are each surmounted by a Nesslerising tube and illuminated from beneath by reflection from a dull white surface. The room may be darkened. The tubes are filled as indicated in the diagram. To the tube B standard acid or alkali is added till the colours seen looking down the two tubes match. When they do so, the contents of B have the same ionic concentration as the chosen Sorensen mixture.