Mineral Waters. 265 



conclude that if any water turns the infusion of 

 violets red, it certainly contains an acid of which 

 the most minute quantity tinges the infusion. 



Alkaline salts are seldom found in a separate 

 state, but often in a state of combination with 

 the muriatic acid. To discover them in their 

 unsaturated state, we may use the syrup of vio- 

 lets, which is still more delicate with regard to 

 alkalies than acids. A very small quantity of 

 alkali turns it green. If we use the syrup of 

 violets, we must take care that it contains no 

 acidity, which may be prevented by adding 

 minute quantities of alkaline salts as long as the 

 syrup will bear it without changing to a green ; 

 but the infusion of dry violets, or paper stained 

 with them, answers best. 



The infusion of turmeric, or paper stained 

 with turmeric, is also rendered brown by alka- 

 lies, or reddish-brown if the quantity is minute. 

 Paper stained with Brazil wood is rendered blue, 

 but this is also effected by the alkaline and 

 earthy carbonats. When the changes are only 

 temporary, it is generally concluded that the al- 

 kali is ammonia. 



Mineral waters sometimes contain a fixed, and 

 sometimes a volatile alkali. To determine which 

 of the two any particular water contains, we may 

 add to the water a small quantity of muriate of 

 mercury, which is precipitated by the fixed al- 

 kali in a reddish-brown powder, but is precipi- 

 tated by the volatile alkali in a white powder, 



TOL. II. N 



