Twaddell scale
The Twaddell scale is a hydrometer scale used for measuring the specific gravity of liquids relative to water. On this scale, a specific gravity of 1.000 is reported as 0, and a specific gravity of 2.000 is reported as 200.[1] For example, concentrated sulfuric acid with a specific gravity of 1.8 has a Twaddell scale measurement of 160, reflecting the linear relationship between readings and specific gravity. The Twaddell scale is used exclusively for liquids with specific gravity greater than that of water.
This scale was historically employed in the British dye and bleach manufacturing industries. While the Baumé scale was widely adopted across England, the Twaddell scale remained in use in both England and Scotland.[2]
The scale is named after William Twaddell, a scientific instrument manufacturer from Glasgow, who first developed hydrometers using this scale at the beginning of the 19th century.
Converting between Twaddell scale and specific gravity
[edit]let a = any degree of Twaddell's Hydrometer, x = specific gravity in relation to water taken at 1.000
References
[edit]- ^ C.R.A. Wright, On the valuation of solutions for technical purposes by means of the hydrometer in Practical Magazine, Volume 1 Simpkin, Marshall & Co., 1873, page 239
- ^ Griffin, John Joseph (1873). Scientific Handicraft: A Descriptive, Illustrated, and Priced Catalogue of Apparatus, Suitable for the Performance of Elementary Experiments in Physics. Glasgow: J. J. Griffin and Sons. p. 77.
- ^ Griffin, John Joseph (1877). Chemical Handicraft: A Classified and Descriptive Catalogue of Chemical Apparatus, Suitable for the Performance of Class Experiments, for Every Process of Chemical Research and for Chemical Testing in the Arts. Accompanied by Copious Notes, Explanatory of the Construction and Use of the Apparatus. Glasgow: J. J. Griffin and Sons. p. 51.