AGRICULTURAL TEXT-BOOK. 21 



of the different salts is variable ; the soluble salts, particularly 

 the chlorides, were found in this instance to diminish ; while the 

 insoluble, or difficultly soluble salts, gypsum and carbonate of 

 lime increased as the site of the spring was at a lower level. 

 The nature of the soil, likewise, alters the relative quantities of 

 the different salts. The chlorides preponderate in magnesian 

 soils, and vary from 25 to 32 per cent, while in anthracitic soil 

 they do not amount to more than 10 or 16 per cent., and in 

 calcareous soil to only between 4 and 8 per cent, of the saline 

 matter. The sulphates are found in nearly the same proportions 

 in calcareous and anthracitic soils ; in the former, they vary from 

 24 to 31, and in the latter from 18 to 37 per cent. In the 

 Nicomien, they do not amount to more than 5 or 12 per cent, 

 of the dissolved saline matter. The carbonates vary from 36 

 to 47 per cent, in granitic soils; from 48 to 71 in anthracitic, 

 and from 83 to 88 per cent, in chalk soils. Soda salts, (chlorides 

 and sulphates,) preponderate in magnesian, and particularly in 

 anthracitic soils; the total quantity of sulphates in the latter 

 soils is much greater. Magnesian salts are remarkably constant 

 in water from magnesian and anthracitic soils; their relative 

 quantity averages between 19 and 23 per cent in water from 

 granitic salts and slates; and between 11 and 23 in anthracitic 

 formations. ( Kn app.) 



64. The quantity of saline and earthy matter in spring water, 

 varies from about 20 grains to 1,800 grains in the gallon; when 

 above 100 grains per gallon, it constitutes a mineral water. The 

 average quantity in ordinaiy spring water is from 20 to 80 

 grains. The most common salts are sulphate and carbonate of 

 lime, sulphate, muriate, and carbonate of potash and soda. 



65. The presence of phosphoric acid in some waters has re 

 cently been discovered. 



66. Three-fourths of the weight of the body of man and of 

 the higher animals is composed of water ; and the lower ani 

 mals are constituted in like manner. Even the wood of trees 



