WATER SOLVENT ACTION OF WATER, ETC. 47 



soil is well supplied with decaying organic matter. It is 

 probable that the carbonic acid in the soil solution is the 

 most effective means for dissolving tricalcium phosphate, 

 thus making it available as a plant food. 



Table II shows the difference between the solvent action 



FIG. 13. The shallow barnyard well, with privy vault and manure 

 heaps near by. The water is likely to receive fluid from these 

 any time. (From Smith's " Sewage Disposal on the Farm," 

 Farmers' Bulletin, No. 43, U. S. Department of Agriculture.) 



of water charged with carbon dioxide and of distilled 

 water. The marked increase in the solvent power of 

 water when carbonated is clearly indicated. 



During the process of decomposition of organic matter, 

 the nitrogen is changed in form. The organic compounds 

 of nitrogen are changed by the ammonifying bacteria into 



