fl5 ON THE ELECTRIC COLUMN, 



commouly assumed ; air has no share in it. The iuamedit-te 

 product of evaporation in all its stages, from the formation 

 of steam by boiling water, down to the evaporation of ice in 

 winter, is constantly and uniformly an expansible Jiuid, 

 composed of water and Jire, namely the aqueous vapour. 

 This Jluid, in whatever temperature it is produced, acts by 

 pressure, in the same manner as the aeriform Jiuids, and in 

 particular pu the manometer, from the instant of its produc- 

 tion, as long as it subsists ; and the quantity of its produc- 

 tion, attended with a proportional pressure, is the same in 

 vacuo as in air» at its different majrima correspondent to each 

 ^e^ve& of temperature ; a direct proof that air has not the 

 smallest share in evaporation. Lastly, as Ipng as this fiuid 

 uubsists without any change in its natur^ it never ceases to 

 act upon the hygrometer, and its quantity is exactly mea- 

 sured by this instrument, with the addition of the tkermor 

 Vieter. I have proved these assertions by the union of Mr. 

 de Saussure's experiments and mine, in some papers pub- 

 lished in the Phil. Trans, of 1793. It is evident, that, if 

 these be xq^A facts, the resource of the new theory of che- 

 mistry for explaining rain is overturned (as will be seen here- 

 after), and with it the theory itself; what then is the reason, 

 that those, who still maintain it, remain silent on these^ec?*.^ 

 On this however rests (and will continue to rest till the con- 

 trary be proved by direct experiments) the whole of meteo- 

 rology. 

 'Jhem^xi- Art. II. Both Mr. de Saussure an4 myself have deter- 



mum of aque- njined, by direct experiments reUted in our respective works, 

 ous vapour at » , ,, • , , i o i . . 



every tempefa- »» A shall more particularly express herearter, the quantities 



■,tu a fixed of ^t"fl;)Ora^eri «?a/ffr contained in one cubjc foot of flir cor- 

 • respondent to every degree of our hygrometers, at every tern* 



perature; and we have proved, that the maximum of this 

 water, a quantity fixed for every temperature, cannot be ex- 

 ceeded, either by the increase of water in the same space, 

 or by the diminution of heat with the same quaptity of this 

 water, without sonoe of the aqueous vapour being decom- 

 posed, and «;«/er making its appearance by precipitation: 

 und by my expeviments it is moreover demonstrated, that 

 no length of time, alter the production of th\»fluid, can pre- 

 sent either its effect pn the hygrometer, or its remaining 



submitted 



