310 M. Dutrochet's Observations on the Fontaine Ronde. 



the spring flows uninterruptedly and abundantly while the level 

 sinks ; but as the swelling begins, air bubbles rise every where 

 from the water, and even from that part of the spring which is 

 the seat of the constant flow. This observation proves that the 

 carbonic acid is not constantly mixed with the water in the sub- 

 terranean canals, but only reaches them periodically; hence, pro- 

 bably, this periodic flow of the gas into the subterranean canals 

 is the cause of the rising of the spring. There is an opening, 

 partially filled with stones, at the foot of the hill, about fifteen 

 feet from the spring, by which the spring, in the winter, when it is 

 very powerful, pours out its superfluous water, but which is dry 

 during the rest of the year. When we apply our ear to this 

 opening we hear, as long as the rising of the spring continues, 

 a pretty loud bubbling noise ; but during the ebb or decrease 

 of the spring, no noise is to be heard. This subterranean 

 bubbling arises, in all probability, from a very considerable 

 evolution of gas. This proves, again, that the gas which occa- 

 sions the rising of the spring, is not entirely carried off" by the 

 water, but that a greater part is developed under the surface of 

 the earth, and escapes by means of other canals, very probably 

 by the opening just mentioned. 



We shall not enter into any hypothesis as to the cause of 

 this periodic evolution of gas, but rest satisfied by pointing out 

 its occurrence at the same time with the periodic rising of the 

 spring*. 



In the Jura there are other periodic springs, as in the town 

 of Siam in the Canton of Champagnole. Its flux or rise con- 

 tinues seven minutes, its ebb six minutes ; its period, therefore, 

 is thirteen minutes. But I did not observe any evolution of gas 

 in this spring. — Annul de Chim. et Phys. t. xxxix., p. 230. 



• Vide Manchester Memoirs, for an ingenious paper by Mr Gooch on this 

 subject— Editor. 



