202 COSMOS. 



waters without access of air ; indeed the Kaiserquelle alonfl 

 contains 0.31 per cent, of sulphuretted hydrogen in gas 

 bubbles which rise spontaneously from the springs. 56 



A thermal spring which gives rise to an entire river of 

 water acidified by sulphur, the Vinegar river (Rio Vinagre), 

 called Pusambio by the aborigines, is a remarkable pheno- 

 menon to which I first called attention. The Rio Vinagre 

 rises at an elevation of about 10,660 feet on the north- 

 western declivity of the volcano of Purace, at the foot of which 

 the city of Popayan is situated. It forms three picturesque 

 cascades. 57 of one of which I have given a representation, 

 falling over a steep trachytic wall probably 3.20 feet in per- 



Eendicular height. From the point where the small river 

 Jls into the Cauca, this great river for a distance of 2 3 

 miles (from 8 to 12 English miles) downwards, as far as the 

 junctions of the Pindamon and Palace, contains no fish ; 

 which must be a great inconvenience to the inhabitants of 

 Popayan, who are strict observers of fasts ! According to 

 Boussingault's subsequent analysis, the waters of the Pusam- 

 bio contain a great quantity of sulphuretted hydrogen and 

 carbonic ac.d, with some sulphate of soda. Near the source, 

 Boussingault found the temperature to be 163. The upper 

 part of the Pusambio runs underground. Degenhardt (of 

 Clausthal in the Harz), whose early death has caused a 

 great loss to Geognosy, discovered a hot spring in 1846 in 

 the Paramo de RVJ'Z, on the declivity of the volcano of the 

 same name, at the sources of the Rio Guali, and at an alti- 

 tude of 12,150 feet, in the water of which Boussingault 

 found three times as much sulphuric acid as in the Rio 

 Vinagre. 



The equability of the temperature and chemical constitu- 



56 Liebig and Bunseu, Untersuchung der Aachener Scheivefelquetten, in 

 the Annalen der Ckemie und Pharmacie, Bd. Ixxix (1851), s. 101. In 

 the chemical analyses of mineral waters which contain sulphuret of 

 sodium, carbonate of soda and sulphuretted hydrogen are often stated 

 to occur from an excess of cai-bonic acid being present in those waters. 



5 ~ One of these cascades is represented in my Vues des Cordilleres, 

 pi. xxx. On the analysis of the water of the Eio Vinagre, see Boussin- 

 gault. in the .Annales de Ckimie et de Physique, 2e, s6rie, t. lii, 1833, 

 p. 397. and Dumas., 3e serie, t. xviii, 1846, p. 503; on the spring in the 

 Paramo do Ruiz, see Joaquin Acosba, Viajes Cientificos d los Andet 

 Ecuatoriales, 1849, p. 89. 



