ECONOMICAL PROCESS FOR EVAPORATIOJJ. 373 



plctcst theory. I will, therefore, trespass no farther on 

 the limited space of your valuable Journal. By giving a 

 place in it to the above observations, you will render an im. 

 portant service to the cause of chemistry ; as they must 

 cither draw from the ingenuity of Mr. Davy a reconciliation 

 of the differences, and thus confirm, by undeniable and 

 irresistible evidence, the justness of his ideas; or they 

 must inevitably confirm the insufficiency of his ingenious hy- 

 pothesis. For I am certain, that no one can for an instant 

 doubt the justness of the principle. upon which they are 

 founded, viz. that in the case where two compound bodies 

 are submitted to mutual decomposition, the elements of 

 these bodies must either be totally absorbed, and (if I may 

 "be allowed the term) neutraHzed by a fresh combination ; 

 or they must appear in their own peculiar form, and with 

 their own distinguishing characters. 

 I remain, Sir, 

 Your most obedient servant, and constant reader, 

 13M oj Jpril, 1811. F. D. 



VII. 



J)escnption of an ecenomical Process for Evaporation^^ in^ 

 vented by the late Mr. Joseph Montgolfier ; by Messrs* 

 Desormes cz??d Clement *. 



Vy* ONSIDERING the great effect of spontaneous evapo^ Spontaneous 



ration, that takes place from the simple contact of air with ^y.^P^ration ap. 



' '^ ^ plied to econo- 



huraid substances, or with water itself, Mr. Montgolfier micalpurposrn 



imagined, that the same means might be employed for dry- 

 ing without the assistance of fire a great number of matters, 

 which are liable to be injured by its application. The 

 instances of natural salt-pits, and graduation houses, oc- 

 curred to him, in which evaporation is conducted very «co- 

 nomically : but the former are adapted only to hot climates, 

 and the latter depend too much on the state of the at. 

 mosphere, to be applicable to the principal object he had in 

 view, the desiccation of alimentary substances ; an opera- 

 tion of which the object was to preserve them a long time 

 * Abridged ftova the Amiales de Chimie, vol. ixxvi, p. 34. . 



without 



