REPORT ON MINERAL AND THIiRSIAL WATERS. 3 



Nitric acid, indeed, seems to be spontaneously generated from 

 its elements under certain circumstances as yet but i)iiperfectly 

 understood, as during the decomposition of water by ^•oltaic 

 electricity*, and in the case of the formation of nitre on walls. 

 We need not, therefore, be astonished to find it sometimes pre- 

 sent in atmospheric water. Common salt is also taken up in 

 small quantities by aqueous vapour, and the same is the case 

 with many other alkaline and earthy compounds. 



But the existence of metallic bodies in the atmosphere re- 

 quires further confirmation, although I am not disposed to reject 

 the statements of Zimmermann on this point as altogether un- 

 worthy of examination. Fax-aday indeed has shown f, that such 

 matters cannot be suspended there by the mere repulsive force 

 of heat, since every substance, according to his experiments, 

 possesses a certain fixed point, below which no spontaneous vo- 

 latilization of its particles takes place, and the limit of volati- 

 lity in these metals greatly surpasses the highest temperature 

 which the atmosphere ever attains. 



Still, however, it becomes a distinct question, whether such 

 bodies may not exist there bj^ virtue of their affinity for others ; 

 and experiments recently made in Italy seem to show, that in 

 some manner or otlier they are so suspended. Thus, FusinieriJ 

 has stated, that electrical light carries with it metallic bodies in 

 a state of incandescence, and that ordinary lightning deposits 

 upon the substances with which it comes into contact, sulphur, 

 and iron, in a metallic, as well as in an oxidized, condition. 

 Hence according to him arises the smell which always accom- 

 panies thunder, and hence the pulverulent m.atter deposited 

 round the fractures occasioned in those solid bodies which the 

 lightning traverses. 



The connexion of these researches with the origin of meteoric 

 stones is too obvious to require our ij3sisting on ; and hence it 

 becomes of the more importance that some fresh experiments 

 and observations should be set on foot, in order that the ques- 

 tion may be finally determined. 



To conclude my account of the foreign bodies met with in 

 meteoric water, I may mention, that the fact of carbui-etted hy- 

 drogen having been detected in the water of rain, snow, aiid 

 hail, is the more credible, inasmuch as Boussingault§ has found 

 this same gas in the atmosphere surrounding large cities. 



With respect to sea-water, the next modification of this fluid 2ndiv. Wa- 

 ter of Seas. 

 * See Davy's Experiments, 1S07, Philosophical Transactions, 

 f Plvhsophical Tfansactions, vol. cxvi. p. 2. 

 X Becquerel, Traite d' Ekciricite, vol. iii. p. 157. 

 § Annales de CkimiP. 



B 2 



