178 T.S. Hunt on the Chemistry of Natural Waters. 
5 
than sulphates, chlorids, or carbonates of soda, lime and mag 
nesia. In this way the mineral matters required for the growth — 
of plants, and by them removed from the soil, are again restored 
to it; and from this reaction results the small proportion of 
potash salts in the waters of ordinary springs and wells as com — 
pared with river-waters. From the waters of rivers, lakes, and 
seas, aquatic plants again take up the dissolved potash, pho} — 
phates, and silica; and the subsequent decay of these plants | 
contact with the ooze of the bottom, or on the shores, againIe 
stores these elements to the earth. See a remarkable essay by 
Forchhammer, on the composition of fucoids, and their gedlog 
nor absolute. It would appear, on the contrary, that there takes 
place a partial exchange or a partition of bases according © 
their respective affinities. Thus the normal chabazite 1m pr 
ence of a solution of chlorid of sodium one a large 
Proportions of ammonia and potash in natural waters are d 
Small, when compared with the amounts of lime 4 pet 
_ existing in the form of hydro-silicates in the soil, the rnonis 
: affinities is an almost complete elimination. of the ammr" a 
me That the replacement of one base by another ss of Di 
1g, Dehérain and others, who have observed that a sol al : 
Sypsum removes from soils a certain amount of Powe tg 
_ whieh was insoluble in : i 20 
aay’ sli aa: 1 pure water. In this way gyPs® 
pa te ae portions of sulphate of soda, and perbap 
bike of magnesia, from silicates. 
This Journal, [2] xxviii, 72. 
