238 BOARD OF AGRICULTURE. 



that both of these elements can be left out almost entirely, 

 without making any difference in tlie products. Yet common 

 salt acts as a fertilizer, not by feeding the plant, but by its 

 action upon the soil. 



Some years ago, two chemists, one in Germany (Baron Lie- 

 big), and another in France, made some observations, inde- 

 pendently, which throw light on this question. The French 

 chemist procured samples of different soils, some of which 

 were benefited by plaster, and others of which were not 

 affected by plaster, and treated each of the samples with water, 

 to see wliat the water would take out of them. He took also 

 similar samples of each of the soils, and poured-on them the 

 same amount of water, in which he had dissolved all the 

 plaster that it would take up. Pure water will dissolve one 

 part plaster to about four hundred and fifty parts of water. 

 Almost all hard water contains a little plaster in solution. He 

 used pure water in one case and a solution of plaster and 

 water in the other case, and kept the mixture in agitation for 

 a number of days, and then drew off the liquid and made a 

 careful analysis of it. He found that those soils which were 

 not benefited by plaster gave to the pure water the same 

 quantities of certain elements, principally potash and magne- 

 sia, which they gave to the water containing plaster ; the plas- 

 ter made no diflerence in the ability of the water to dissolve 

 those substances; but on the soil which plaster benefited, 

 those two materials, potash and magnesia, were taken up by 

 the plaster water in much greater quantity than by the pure 

 water. 



It is this solvent effect of plaster upon the soil which must 

 be taken into account in considering its action, and the action 

 of common salt upon the soil. That is the explanation of the 

 action of salt upon our ordinary farm crops. All these mate- 

 rials which enter into the growth of plants have, in addition 

 to their direct action as feeders of }»huits, this indirect action 

 upon the soil, and therefore it is impossible to say, in any 

 given instance, in what way a fertilizer acts, and it is impossi- 

 ble to say what will be its action without making a trial. All 

 we can do is, to use these gei^eral facts, as we gather them, in 



