ON THE ELECTRIC COLUMN. S53 



and in showers^ sudden, and somelimes violent winds ac- 

 company these, arising from the expansion of the air, by its 

 decomposition into aqueous vapour, in some place, while a 

 vacuum is produced in other parts, by the resolution of that 

 vapovT into rain. Hence it is, that the direction of these 

 wind* is rapidly changing, and that they cease with the re- 

 turn of the transparency of the air. Lastly, in a stratum 

 of air, which perhaps only half an hour before was calm and Storm* 

 transparent, in which the hygrometer did not indicate any 

 increase in the small quantity of evaporated water, and with- 

 out any indication of increase of the quantity of electric 

 Jluid, some clouds, rapidly forming, produce lightning, 

 thunder^ haih torrents of rain, and such violent winds, as 

 tear up trees and overturn cottages on mountains. 



We may be for ever ignorant of the causes of these won- 

 derful phenomena, but those who are aware that fiction, in 

 the operations of nature, may lead to great errours, will pre- 

 fer ignorance to a false science. As for me, from my first 

 observations of these operations of unconstrained nature, 

 *nd with the addition of a remark of Mr. deSaussure which 

 I shall mention, I changed very essentially my former ideas 

 on the atmospheric phenomena, as 1 have explained in my 

 works, and shall repeat hereafter. 



Art. XIII. In order to evade the general consequence, Fourcroy's hy- 



which, in my works, I have deduced from these facts, pc'thesisofa 



,,.,,, , flry solution oi 



namely, that rain and the other concomitant phenomena are ^^ter in air. 



produced by different kinds of decompositions of the atmos" 

 phericair; which consequence is certanily the subversion 

 of the new theory of chemistry; Mr. Fourcroy invented the 

 hypothesis of a dry solution of water by air; supposing, 

 that this water could no longer affect the hygrometer, v/h\ch 

 in consequence he discarded from the rank of a meteorolo" 

 gical instrument ; and having obtained the assent of many 

 chemists, who have not applied to meteorology any more 

 than himself, this instrument, so much wished for before by 

 natural philosophers, is now hardly mentioned. 



But this hypothesis, grafted on that of Le tloy^ is in the 

 first place absolutely g-ra/wifoj/*; no fact having been ad- 

 duced in bringing it forward in chemistry against the posi# 

 tive facts contained in Mr. de Saussure's works and mine : 



«nd 



