POWEEFUL EFFECT OF CARBONATED WATER. 75 



solving power of water might be mentioned, 

 but none so strikingly illustrate the fact as those 

 here detailed. The mechanical influence of 

 water upon our sea-coasts will receive notice in 

 another part of this work. We must pass by, 

 however, the simply mechanical and solvent 

 powers of water as concerned in the phenomena 

 of nature, to the far more important considera- 

 tion of its chemical effects. 



In this respect that is, as a chemical agent 

 water acts chiefly as a vehicle for the applica- 

 tion of another chemical body Carbonic acid. 

 This gas is capable of being largely dissolved 

 by water, and so becomes peculiarly applicable 

 to fulfil the duties of a chemical agent, since 

 such bodies always act most readily in solution. 

 It has been found that felspar, which forms a 

 great part of the hard' rocks, granite and por- 

 phyry, will withstand, almost without injury, 

 for some time, the action of cold muriatic acid, 

 which is a powerfully corrosive, fuming liquid. 

 But water, charged with carbonic acid gas, 

 affects it rapidly, causes it to decompose, and 



months. In a pond into which they are conducted, they have 

 deposited a solid mass, thirty feet thick, in the period of 

 twenty years. The mineral contents 'of the water are turned 

 to profitable account by the establishment of a manufactory 

 for medallions in basso-relievo. Moulds are exposed to the 

 spray of falling waters, and in a short time are coated over 

 with a beautifully white crust, as hard as marble. 



