The extra pharmacopoeia / by William Martindale ... and W. Wynn Westcott.

  • Martindale, William, 1840-1902.
Date:
1901
Catalogue details

Licence: In copyright

Credit: The extra pharmacopoeia / by William Martindale ... and W. Wynn Westcott. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    15/724 (page 11)
    WEIGHTS A^]) MEASURES. tot The British Pharmacopoeia has now adopted a dual system of weights and measures in all its formulae, except those employed for testing, and states that:— The alternative employment, iu the British Pharraaeopociaa ' of 1867 and 1885, of metric weights and measures in the pai a- ' graphs relating to volumetric analysis, is now extended to ' every official paragraph wliich makes reference to the usual ' Imperial weights and measures ; but the metric system alone ' is employed in all paragraphs relating to analysis, whether ' gravimetric or volumetric. ' During the period of transition from the Imperial to the ' metric system a certain amount of confusion is likely to ' occur. It has been somewhat difficult, in the course of a ' single paragraph, to embody formulte involving definite ' quantities of materials, and to give precise directions for ' their employment, in two different systems of weights and ' measures ; and those who use the Pharmacopoeia are ' requested to avoid the assumption that Imperial and metric ' quantities thus placed in juxtaposition are necessarily equivalent to one another. They are approximately equiva- leut in paragraphs on crude drugs ; they are not equivalent iu paragraphs which describe the manufacture of galenical preparations. Except for wholly insignificant fractional ' differences, a preparation made according to either system ■ will contain the same proportions of ingredients ; but, as a ' matter of course, the two systems cannot both bo used in the ' same operation. ' It is to be regretted, from a theoretical point of view, that ' the graduation, and in certain cases the employment by ' analysts, of Imperial and metric vessels for purposes of ' measurement, and the adjustment and in most cases the ' employment of vessels for determining specific gravities, are ' not conducted at one and the same temperature. But the ' practical advantage of rendering these temperatures identical ■ would be insignificant, while the resulting confusion would