STATE POMOLOGICAL SOCIETY. 73 



day ; in the poisonous fumes from burning charcoal, in the fire 

 extinguisher, and in the sprightly taste of spring water. In a 

 solid state it forms 44 per cent, of all the limestone in the world. 



Now there must be a use for this substance somewhere in the 

 economy of nature ; and with the hope of meeting the approval of 

 the Society, I will endeavor to explain somewhat fully its action, 

 I hold in my hand a coarse, granite rock. You notice on the side 

 which has been exposed to the weather, that it has a white, 

 chalky appearance. Now the carbonic acid in a state of solution 

 in water has the power of attacking a granite rock and setting 

 free the potash. This carbonic acid is the principal agent in 

 decomposing every rock you see crumbling to pieces. The mo- 

 ment it sets at liberty a particle of potash it combines with it and 

 makes it soluble in water. Whenever the carbonic acid in the 

 soil is in large quantities, or as chemists say, in excess, it forms 

 bicarbonate of potash, soda, magnesia and lime. All these new 

 compounds are ver\' soluble in water. The carbonic acid will not 

 touch a particle of the sand or clay in the rock, and these two 

 substances are simply set at liberty. Every intelligent farmer has 

 been taught, that if one proportion of phosphoric acid is combined 

 with one of lime, it forms a phosphate of lime, but it is not readily 

 soluble in water and is almost useless as a manure ; but when two 

 parts of the phosphoric acid unite with one of the lime he then 

 has a biphosphate of lime, or what is sometimes called superphos- 

 phate of lime, which, in this condition, is very soluble in water, 

 and a ready food for plants. 



Let us go back to our carbonic acid. When it is in excess in 

 water, it combines in the proportion of two parts of the acid to 

 one of the potash, soda, magnesia and lime, and forms bicarbonates 

 of these substances which are all very soluble in water. These 

 salts become entangled in the soil and are the mineral food of 

 your plants and trees. If these salts find their way into the 

 brooks, the salts of potash, soda and magnesia, are swept into the 

 ocean to keep up the supply of salts there, while most of the lime 

 will, on exposure to the air, lose one part of its carbonic acid, and 

 be precipitated to the bottom of the stream in the form of a white 

 powder, and if made solid it would become limestone or marble. 

 Iron will precipitate to the bottom of running streams in the same 

 way, and form beds of iron ore. 



Now, gentlemen, this is just what is constantly going on right 

 before your face whenever you cultivate the soil. This carbonic 



