On that form of chemical hygrometer in which sulphuric acid has been used as the absorbent : the Johnson memorial prize essay for 1891 / by M.S. Pembrey.

  • Pembrey, M. S. (Marcus Seymour), 1868-1934.
Date:
[1891]
Catalogue details

Licence: Public Domain Mark

Credit: On that form of chemical hygrometer in which sulphuric acid has been used as the absorbent : the Johnson memorial prize essay for 1891 / by M.S. Pembrey. 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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    satiated^ in the moistest weather; it afterward retains or looses its acquired weight as the Air proves more or less moist.” Although Gould’s method was by far the most accurate of the other forms of hygroscope used at that time, yet it is evident that it could never give exact and comparable indications. Its chief defects were that the air during a series of observations was not brought into equal relation- ship with the absorbing liquid, that no precaution was taken to entirely deprive the air of moisture, and that the absorbing surface was soon rendered defective by the ab- sorption of water. No other form of sulphuric acid hygrometer was intro- duced until about 130 years after the publication of Gould’s paper, when, according to Symons the arrangement pro- posed by Gould was re-introduced by Guyton de Morveau in 1808. This apparently is a mistake, for in the paper by Guyton de Morveau ^ chloride of calcium only is de- scribed as the absorbent, and both Schmid ^ and Brunner when speaking of the hygrometer of Guyton Morveau, only name chloride of calcium. In 1819 John Livingstoneof Canton, published an “ Account of an Improved Hygrometer,” which was indeed only the re-introduction of the method employed by Gould. The apparatus described by Livingstone consisted of a watch glass, which contained 2*1 grains of pure sulphuric acid and 2-9 of water, and was placed in a balance. The arc described by the balance was graduated, so that it was possible from the readings to calculate the amount of moisture absorbed. The instrument was enclosed in a glass cover, sufficiently open below to admit the air freely. This hygrometer had all the defects of Gould’s apparatus. Again in 1824 Gould’s apparatus was re-introduced by Kastner. This statement is made on the authority of ^ “A Contribution to the History of Hygrometers,” Meteorol. Soc. Quart Joiirn., vol. vii. p. 171. ^ Annales de Chimie, t, Ixviii. p. 5. ^ Lehrhuch der Meteorologie, Schmid, p. 604. * Aronden der Physit and Cheririe, Poggendorff, Band xx. p. 274. ^ Edinhunjh p]tiIosopl/icaI Jountat vol. i. 1810.