[ 3^4 ] 



Section IV. 



Of the Injluence of EleElricity and Light. 



That ekElricity powerfully affifts evaporation is generally ac- 

 knowledged. Sauffure has fhewn that a card, fuperfaturcd with 

 moifture, loft, when eledrified, two grains in a quarter of an hour, 

 while another equally circumftanced, but not eledrified, loft only 

 i^ grain : but he limits its adion to water in a free and uncom- 

 bined ftate. Hygrometer: § 159 and 1 60. Briffon alfo has ob- 

 ferved, that an excited eledric raifes water above its level. 

 Mem. Par. 1767, p. 328, 8vo. But how it ads in the ope- 

 rations of nature is but imperfedly known. 



Light alfo contributes to evaporation by difengaging air from 

 water, and perhaps for other reafons as yet imperfedly known. 



Section V. 



Of the joint AS'ion of the above-mentioned Catfes. 



The only feries of bbfervations with which I am acquainted, 

 made on evaporation, in which the principal caufes that concur 

 in producing it admit of a diftind confideration, being marked 

 by accurate inftruments and precife meafures, are thofe of Mr. 



Achard 



