426 Scientific Intelligence. — Hydrology. 



the terrestrial strata whence the water now issues, must have 

 possessed at the time of the Romans and Carthaginians a tem- 

 perature of 100°.3 Cent , and consequently the water would have 

 appeared at the surface in the state of steam, as in the geysers of 

 Iceland^ and not in the state of hot water only. But who can 

 admit the existence of so extraordinary a phenomenon, when 

 Seneca, Pliny, Strabo, Pomponius Mela, &c. are wholly silent 

 reo^ardinff it. 



Our argument seems liable only to one kind of difficulty ; 

 solutions will not boil at a temperature of 100° Cent,, as pure 

 water does, and the difference will increase in the ratio of the 

 quantity of saline matter which is dissolved. And this is the 

 precise reason why new observations on the hot-spring in 

 the neighbourhood of Bona are indispensable. It is on this ac- 

 count necessary to add to the determination of temperature, a 

 chemical analysis of the water, an analysis which, however, can 

 easily be made at Paris, upon specimens inclosed in bottles hei- 

 metically sealed. If, at the present time, the water of the 

 spring reaches the surface very nearly saturated with the cal- 

 careous matters which it deposits, every difficulty will disap- 

 pear, and an important problem in climatology will then be 

 resolved. — Arago. 



10. Electricity near Waterfalls, — In the year 1786, Tralles 

 found, near the waterfall of the Staubbach, that the extremely 

 fine rain, which was detached from it, gave manifest signs 

 of negative electricity. The Reichenbach also presented the 

 same phenomena. Shortly after, Volta verified the accuracy 

 of the observation of Tralles, not only at the waterfall of 

 Pissevache, but also every where when a fall of water, how- 

 ever insignificant, gave occasion, by the intervention of the 

 wind, to the dispersion of the minute globules. It appeared to 

 him, as it did to Tralles, that the electricity was always nega- 

 tive. The philosopher at Berne at first attributed the electri- 

 city of the watery vapour, with which all great cascades are 

 surrounded, to the friction of the globules upon the air ; but 

 shortly afterwards he saw, along with Volta, the true cause of 

 this electricity in the evaporation which these same globules 

 experienced in the act of falling. This explanation has lately 

 been combated by Professor Belli. Without denying that 



