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VIII. Proposed Improvement of the Hygrometer, 

 By J. Berzelius*. 



Ualton's admirable researches have at last decided the 

 dispute respecting the water of the atmosphere, which had 

 lasted for nearly a whole century. The least absurd of the 

 ideas advanced on the subject was, that the water became 

 dissolved by the air, much in the manner as other solid bo- 

 dies are dissolved by water, and that the aqueous meteors 

 depended on alterations in the solvent capacity of -the air, 

 whereby the water is sometimes precipitated, producing 

 clouds and rain, and at times dissolved, producing exhalations. 

 But Dalton has proved, that the water of the atmosphere 

 is independent of the air; and that if the earth were deprived 

 of the latter, it would nevertheless be surrounded by aqueous 

 vapour, the extent of which would depend upon the degree 

 of heat only ; its increase in an increase of temperature being 

 rather hindered than promoted by the air. The water con- 

 tained in the air is in a gasiform state, mixed with the at- 

 mospheric air, just as in this the oxygen is mixed with the 

 nitrogen, or as water is mixed with any other fluid. The 

 quantity of water-gas in the air (as we have said) is in pro- 

 portion to the temperature*; and if the latter were immu- 

 table, the former would also continue the same ; but per- 

 petual changes of sitifations, circumstances, and tempera- 

 ture, produce continual alterations in this gas of the air, and 

 from this alone are most of the aqueous meteors derived. 

 Dalton, by a series of experiments, has calculated the, quan- 

 tity of water capable of maintaining a gasiform state, cor- 

 respondent with every degree of the thermometer ; and in a 

 separate, table determined these quantities according to the 

 different columns of mercury they support. For instance, 

 at _ i5°f it is equivalent to a column of 0-064 inches, at 

 — 5° to 0-120, at OMo 0-183, at + 15° to 0*422, at + 50° 

 to 2*90, and at the boiling point to 25-0 inches, and this in 

 vacuo as well as in the open air. But it seldom happens 



* Translated from Berzclius's Philosophical Journal, 1808. 

 f What Thermometer does M. Berzelius use ? Edit. 



C 4 that 



