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Control of Humidity with Potassium Hydroxide, Sulphuric Acid, or other Solutions

  • M. E. Solomon (a1)

Methods of preparing solutions of graded density for the accurate control of atmospheric relative humidity are described, and some pitfalls in their use and in the use of saturated salt solutions are indicated.

For graded solutions of potassium hydroxide and of sulphuric acid, data from the International Critical Tables or more recent sources are used as the basis of tables giving the concentrations (wt.%) and densities corresponding to relative humidities in steps of 5 per cent. R.H. Sources of similar data for calcium chloride, sodium hydroxide, sodium chloride, and glycerol solutions are given.

As an addition to the compilation of the available data on humidities in contact with various saturated salt solutions by O'Brien (1948), some more recent figures are quoted.

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British Standards Institution. No. 718. (1936). British Standard Specification for density hydrometers. 52 pp.
British Standards Institution. British Standard density-composition tables for use in conjunction with B.S. density hydrometers :—
British Standards Institution. No. 753. (1937). For aqueous solutions of sulphuric acid, 68 pp.
British Standards Institution. No. 823. (1938). For aqueous solutions of sodium chloride and of calcium chloride, 36 pp.
British Standards Institution. No. 824. (1938). For aqueous solutions of caustic soda, 47 pp.
Buxton, P. A. (1931). The measurement and control of atmospheric humidity in relation to entomological problems.—Bull. ent. Res., 22, pp. 431447.
Buxton, P. A. & Mellanby, K. (1934). The measurement and control of humidity.—Bull. ent. Res., 25, pp. 171175.
Carr, D. S. & Harris, B. L. (1949). Solutions for maintaining constant relative humidity.—Industr. Engng Chem., 41, pp. 20142015.
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Bulletin of Entomological Research
  • ISSN: 0007-4853
  • EISSN: 1475-2670
  • URL: /core/journals/bulletin-of-entomological-research
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