148 HISTORY OF 



Of the purity of all these waters, the lightness, 

 and not the transparency, ought to be the test. 

 Water may be extremely clear and beautiful to 

 the -eye, and yet very much impregnated with 

 mineral particles. In fact, sea water is the most 

 transparent of any, and yet is well known to con- 

 tain a large mixture of salt and bitumen. On the 

 contrary, those waters which are lightest, have 

 the fewest dissolutions floating in them ; and 

 may therefore be the most useful for all the pur- 

 poses of life. But, after all, though much has, 

 been said upon this subject, and although waters 

 have been weighed with great assiduity to deter- 

 mine their degree of salubrity, yet neither this, 

 nor their curdling with soap, nor any other phi- 

 losophical 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 

 different kinds of water are adapted to different 

 constitutions. An incontestable proof of this, are 

 the many medicinal springs throughout the world, 

 whose peculiar benefits are known to the natives 

 of their respective countries. These are of vari- 

 ous kinds, according to the different minerals with 

 which they are impregnated ; hot, saline, sulphu- 

 reous, bituminous, and oily. But the account of 

 these will come most properly under that of the 

 several minerals by which they are produced. 



After all, therefore, we must be contented with 

 but an impure mixture for our daily beverage ; and 

 yet, perhaps, this very mixture may often be more 

 serviceable to our health than that of a purer kind. 



