122 . HISTORY OF 



with soap, nor any other philosophical standard whatsoever, 

 will answer the purposes of true information. Experience 

 alone ought to determine the useful or noxious qualities of every 

 spring ; and experience assures us, that diiferent kinds of water 

 ere adapted to different constitutions. An incontestible prooi 

 of this, are the many medicinal springs throughout the vvorld, 

 whose peculiar benefits are known to the natives of their respec- 

 tive countries. These are of various kinds, according to the dif- 

 ferent minerals with which they are impregnated ; hot, saline, 

 sulphureous bituminous, and oily.* But the account of these 



♦ Mineral waters are divided into four classes, the acidulous, the sulphu- 

 reous, the chnlybeate, and the saline. 



Acidulous waters are those which contain carbonic acid in its free state, oi 

 In combination in excess Witt a base. These waters are easily disting'uished 

 by their slightly acid taste, and by their sparklinff when poured from one 

 vesse. to another ; both of which properties they lose, when exposed to the 

 air for a length of time, or by boiling. Besides carbonic acid, they almost 

 always contain muriate of soda, and some of the earthy carbonates ; it. is the 

 frea carbonic acid, however, that imparts to them their particular properties. 



Sulphureous tvaters are those which contain sulphuretted hydroijeii. Thesa 

 are very easily distinguished by their odour, and by their renderiuga solution 

 of a salt of lead black, or by causing a piece of silver, when immersed in thi'm, 

 to acquire a dark colour. Besides sulphuretted hydrogen, they in general 

 contain alkaline fgjd earthy sulphates and muriates. The sulphureous wa- 

 ters may be subdivided into two kinds ; 1st, Those which have sulphuretted 

 hydrogen in its free state ; 2d, Those in which it exists in union with an 

 alkali or an earth. 



Chali/heiite Ttaters are those which have iron as an ingredient. These are 

 known by their peculiar taste, and by their becoming black when mixed with 

 an infusion of nutgalls. The chalybeate waters are of different kinds ; some- 

 times the iron is combined with sulphuric acid, more frequently it is in union 

 with carbonic acid; this may be just in sufficient quantity to hold the iron in 

 solution, or it may be in excess, in which case, besides chalybeate, the water 

 possesses acid properties, forming what is called an acidulous chalybeate 

 water. 



Saline waters are those which contain the saline ingredients generally 

 found in mineral waters, but which have not carbonic acid in excess, and are 

 free from sulphuretted hydrogen and iron, or contain them in very trifling 

 quantity. Saline waters may be subdivided into four kinds, viz. : — Alkaline 

 waters, or those which contain alkali in its free state, or combined with car. 

 bonic acid, and which render the vegetable blues green. Hard waters, or 

 those which contain carbonate or sulphate of lime. Salt waters, or those in 

 which muriate of soda abounds. Purgative waters, or those which contaifl 

 principally sulphate of magnesia. 



Hot springs are most frequent in volcanic regions. Mo satisfactory ex- 

 planation of the temperature of these springs, and, above all, of their won. 

 derful equability in thio /aspect, for a very long series of years, has ever been 



