ISO SPINGS, RIVERS, CANALS, LAKE5, 



stances : and the certainty of their existence has naturally followed 

 the discovery of methods of ascertaining them. Another cause 

 which has retarded the progress of science in this respect is, that 

 mineral matters dissolved in waters, are almost always hi very small 

 doses, and are also mixed together in considerable numbers, so that 

 they mutually tend to conceal or alter those properties in which 

 their distinctive characters consist. Nevertheless^ the numerous 

 experiments of the chemists before quoted, and a great number of 

 others, which we shall occasionally mention, have shown, that some 

 mineral substances are often found in waters, others scarcely ever 

 met with ; and lastly, many which are never held in solution by that 

 fluid. We shall here consider each class of these substances m 

 order, 



Siliceous earth is sometimes suspended in waters ; and as it is m 

 a state of extreme division, it remains suspender) without precipita- 

 ting , but its quantity is extremely minute. The carbonated alkalis 

 and chalk probably contribute to render siliceous earth soluble. 



Alumine likewise appears to exist in water. The extreme sub- 

 tlety of this earth, by which it is dispersed through the whole mass 

 of water, causes it to render them turbid. Argillaceous waters are 

 therefore whitish, and hare a pearl or opal colour; they are like- 

 wise smooth, or greasy to the touch, and have been called sapona- 

 ceous waters. Carbonic ackl seems favourable to the suspension 

 and solution of alurnine in wnter. 



Lime, magnesia, and barytes, are never found pure in waters; 

 iliev are always combined with acids. 



v v 



Fixed alkalis are never met with in a state of purity in waters. 

 Jut frequently combined with acids, in the form of neutral salts. 



The same observation applies to ammoniac, and most acids, ex* 

 cept the carbonic acid, which is often free, and in possession of alt 

 its properties in waters. It constitutes a peculiar class of mineral 

 waters, known by the name of gaseoits > spirituous, or acidulous 

 waters. 



Among the neutral salts, with basis of fixed alkalis, scarcely any 

 are met with but sulphut of aoda or Glauber's sult^ the muriate 

 of soda, and of potash, and carbonat of soda, which are frequently 

 dissolved in ntificral waters; uitrat and carbonat of potash are 

 mfly found, 



Sulphat of lime, calcareous mnriat, chalk, sulphat of magnesia*. 



