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of Slaked Lime upon soils, and have furnished an invalu- 

 able means of liberating from the soil the alkalis which 

 are indispensable to the existence of plants." Again he 

 says — " It is obvious that mixtures of clay and Lime 

 contain all the conditions necessary for the liberation of 

 the silicate of alumina, and for rendering soluble the alkaline 

 silicates." Dr. Playfair also says that by Liming the 

 land, the silica, potash, and phosphates are liberated from 

 the soil, and administer to the wants of vegetation." Pro- 

 fessor Johnston also holds the same opinion, and says, 

 potash and soda exist to some extent in clay soils in 

 combination with alumina — the presence of Lime has an 

 influence in setting the alkalis free from this state of 

 combination." Supposing, then, that the opinions of these 

 celebrated chemists are correct, it fully explains, to my 

 mind, why it is so frequently maintained, that the repeated 

 application of Lime deteriorates the fertility of land. That 

 such is the effect of a large and frequent application, I 

 have not the least doubt ; and it can be accounted for by 

 the circumstance of each such dose rendering soluble a 

 greater quantity of the potash, silicates and phosphates, 

 than the plant can possibly take up ; the surplus in a 

 state of solution, is therefore carried away by the rains 

 and lost; and the accumulated stock at last exhausted. 

 It appears to me, that according to this view, a small 

 quantity only of Quick Lime, frequently repeated, would 

 be the most economical, and at the same time, effective ; 

 suppose, half a ton every other year, or a quarter of a 

 ton every year, when practicable, or a somewhat larger 

 quantity only when you have a crop which, according to 

 the analytic tables, requires a larger supply of potash — 

 but of course you must first ascertain whether your soil 

 contains a supply of the alkalis, ready to be released. 

 In some of our land at Flockton, according to a minute 



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