128 ACTION OF SALTS. 



equal to 240 lbs. of potash. The quantity of a carbonate of 

 alkali which may be used, will be stated more fully here- 

 after. It is not the object of this work to state quantities to 

 be used, so much as to point out the principles on which 

 salts act. The quantities used must be determined by 

 experiment, and perhaps when the largest amount, which has 

 been stated, is taken for a new starting point, the ultimate 

 quantity will be found limited only by the geine in the soil, 

 or applied in conjunction with the salt. 



170. If we now turn to the other division of salts (158), 

 the poisons, that is, those whose acid forms but a small por- 

 tion of the elements of plants, we find there two classes : 

 First, sulphates, as plaster, copperas, Glauber's salts, all of 

 which, in small quantities, are beneficial. 



Secondly, muriates or chlorides, as they are strictly call- 

 ed, as common salt, muriate of lime, bittern, spent lye from 

 soap-works. An explanation, which attributes the action of 

 sulphate of lime or plaster, to its power of decomposing and 

 fixing in soil, carbonate of ammonia ought to show, 1st, the 

 actual presence of that salt in air ; 2d, that sulphate of am- 

 monia is not decomposed by the resulting carbonate of lime 

 m the cold ; 3d, that common salt would, in equivalent 

 quantity with plaster, produce equally good effects. It 

 never has, and therefore this explanation is not correct. 

 Common salt has been found beneficial when applied at the 

 rate of 30 bushels per acre ; and at 14 bushels per acre, was 

 found to produce effect, next best to 53 bushels of ashes per 

 acre, but quicklime at 26 bushels per acre on the same land, 

 produced no good result. 



171. In all this action of salts, it is seen that the presence 

 of life seems almost essential. Whatever the vital princi- 

 ple may be, it may be best represented as analogous to elec- 

 tricity and galvanism. In this point of view, the salts pre- 



