54 PHOSPHORIC ACID IN WATER. 



76. The quantity of saline and earthy matter in 

 spring-water varies from about 20 grains to 1800 

 grains in the gallon ; when above 100 grains per gal- 

 lon, it constitutes a mineral water. The average 

 quantity in ordinary spring-water is from 20 to 80 

 grains. The most common salts are Sulphate and 

 Carbonate of Lime (230), Sulphate, Muriate, and 

 Carbonate of Potash and Soda. 



77. Thames-water contains usually from seventeen 

 to twenty-four grains of earthy and saline matter per 

 gallon, and of this at least fifteen grains consist of 

 carbonate of lime. The same quantity of New River 

 water contains about nineteen grains of solid matter, 

 and that of the River Lea nearly twenty-four grains. 

 The chief constitutent in both these waters is also 

 carbonate of lime. 



78. The proportion of solid matter is almost al- 

 ways greater in well-water than in that of rivers. 

 A great number of other substances besides those just 

 mentioned are occasionally found in mineral springs; 

 amongst these are silica, alumina, oxides of iron, and 

 manganese, salts of baryta, strontia, magnesia, am- 

 monia, &c. 



79. The presence of phosphoric acid in some \7aters 

 has recently been discovered (194). The following 

 analysis of the deep well-water from below the Lon- 

 don clay, shows the presence of a considerable quan- 

 tity of phosphoric acid. Ten gallons of the water 

 contained five hundred and sixty-four grains of saline 

 matter, consisting of 



