GEATE8. 69 



their solubility. In this dried state, they are earthy 

 powders, and have long been mistaken for earthy 

 portions of soil. The fact, that lime and magnesia 

 form super-salts, (120) may help to explain why 

 the free use of lime, may often require a long time 

 to develope any beneficial effects. At first, its ac- 

 tion renders the geine insoluble ; and it is only when 

 by exposure, the lime is changed in part to a carbon- 

 ate, and thus rendered inert, that a super-geate of lime, 

 which is very soluble, forms and begins to show its 

 effects upon vegetation. The easy decomposition of 

 geate of lime, by alkaline carbonates, teaches also, 

 that if to geate of lime, is added an alkaline carbon- 

 ate, the geine may be dissoluble, and brought into 

 use. It is probable, that when land has been over- 

 limed, the evil can be corrected only, by the use of 

 ashes. The carbonate of lime, will act on the sili- 

 cates, as will be hereafter shown. 



125. The properties and relations of geine with 

 water, are also of the highest agricultural value 

 (116). The great insolubility shows at once how 

 small must be the amount of this portion of soil, 

 which can be ever removed by drainage or filtration, 

 by flood, or rain, and that in the practice of irriga- 

 tion, very little effect can be due to the solvent pow- 

 er of water on geine. Its almost total insolubility. 



