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ash, combined with silica, per acre, would give off double the 

 quantity of soluble potash in a given time to one containing 

 only two, providing the amount of carbonic acid, lime, or 

 other means of decomposition, were the same. And, again, 

 unequal quantities of potash would be rendered soluble in 

 soils where the proportions of silicates were the same^ pro- 

 viding the means of decomposition differed: we might, for 

 instance, in a soil like the one analysed, render double the 

 quantity soluble in one part than another, by supplying it 

 with an excess of carbonic acid or lime. The only means 

 we have of supplying an excess of carbonic acid is by the 

 application of organic matters in the form of manure; the 

 decay of such matters gives rise to an abundance of this gas. 

 Now we find from the analysis that the soil where the red 

 clover died contains considerably less organic matter than the 

 one where it came to perfection ; hence I thought it possible 

 that much less potash would be rendered soluble here than in 

 the latter case, and I took the following steps to ascertain if 

 such were the fact ; both soils and subsoil were exposed to 

 the atmosphere in fine sieves on dishes for three weeks, during 

 which period rain fell frequently, but no liquid was allowed to 

 escape from them ; they were then dried in the air, and the 

 amount of soluble matters which they contained carefully 

 ascertained by analysis. The soil where the clover came to 

 perfection gave .1257 of soluble matters, .0024 of which was 

 potash; and the soil where it failed gave only .0372, of which 

 only .0008 parts were potash. Here, then, is an evident 

 difference in the amount of disintegration, to an extent of 

 one to three; and surely this would produce some effect on a 

 plant which, like the red clover, requires a great quantity of 

 potash for its support. I would not entirely attribute this 

 difference of disintegration to the aid of organic matter pre- 

 sent; the size of the particles containing the potash would 

 have an important effect in increasing or retarding its effects ; 



