Organic Matter found in Sulphureous Springs. 597 



found at Vichy*, and in several other warm springs, that liberate 

 carbonic acid, but are destitute of sulphuretted hydrogen*, and 

 notwithstanding the similarity of external appearance belonging 

 to the specimens of this substance which are taken from different 

 localities, I am inclined to doubt whether they possess anything 

 in common, except the earthy and ferruginous matter with which 

 they are respectively charged. 



In support of this opinion, I might appeal to a drawing exe- 

 cuted by M. Heuland, to whom I am also indebted for that of 

 the Oscillatoria from Greoulx, which represents the appearances 

 exhibited under the microscope by a portion of the red coria- 

 ceous-looking substance, already alluded to as having been 

 found at Bagneres de Bigorre. 



From this it would appear, that the medium, by which the 

 earthy and ferruginous matters disengaged from the water were 

 in that instance held together, consisted of nothing more than 

 the parenchyma of decayed leaves, some of the stomata of which 

 were still visible. 



Without meaning indeed to deny, that Conferva are met 

 with in thermal waters of all descriptions, I am inclined to 

 believe, that they are peculiarly abundant in sulphureous ones ; 

 for it has never occurred to me to witness, in any of the nume- 

 rous mineral springs I have visited in different parts of Europe, 

 an accumulation of organic matter at all comparable to that, 

 which takes place in some of the sulphureous ones of the Py- 

 renees already alluded to ; and, whereas there are many of the 

 purer kinds of hot springs, such as that of Buxton, which do not 

 appear to contain, or to deposit, any organic matter whatsoever, 

 I scarcely know one containing sulphuretted hydrogen, that does 

 not exhibit more or less of it. 



* As that of Campagne in Roussillon, on the road from Carcassone to Perpignan. 



XXXIII. On 



