514 Chemical lefts for Mineral Waters. [Book VII. 



trary, the precipitated matter is fmall in quantity, and 

 fubfides very (lowly ; if it does not effervefce, and af- 

 fords with the vitriolic acid a ftyptic fait, it may be 

 concluded that it is alum, and that the mineral water 

 contained clay: If a bitter and very foluble fait is 

 formed on the addition of the vitriolic acid, it is the 

 Epfom fait, and the water contained the earth of 

 magnefia. If the addition of vitriolic acid to the pre- 

 cipitate produces fal martis, the water held iron in 

 folution. 



The addition of cauftic volatile alkali will aft like 

 lime water, except that k will not produce a precipi- 

 tation from the prefence of uncombined carbonic acid 

 in the water -, the compound formed by volatile alkali 

 with that acid not being infoluble, like the chalk 

 formed by the union of carbonic acid with lime. But 

 befides the aluminous, the magnefian, and the metal- 

 lic falts, the cauftic volatile alkali will decompofe 

 thole which have lime for their bafis, and thus we 

 advance one ftep further in the analyfis of the water. 

 The Pruflian alkali precipitates the combinations of 

 carbonic and vitriolic acid with chalk. The nitrous 

 folutions cf filver and mercury decompofe all the mu- 

 riatic and vitriolic falts, which may be various both in 

 quantity and in kind. In thcfe cafes the muriatic or 

 vitriolic acid contained in the mineral water, feizes the 

 filver or the mercury, and forming with it an infolu- 

 ble compound, falls to the bottom in a thick cloud, 

 while the nitrous acid unites with the bafis which is 

 deierted by one or both of the other acids. It is not 

 neceflary in this place to enter into a minute detail of 

 the methods of diftinguifhing the difference of the pre- 

 cipitates, according as the muriatic or vitriolic acid 

 was concerned in their production, but I fhall refer 

 * the 



