Manures and Chemical Applications. 243 



to be fixed. This salt is soluble; it can be taken up by grow- 

 ing plants, and the elements distributed over their organization. 

 The happy action of even small quantities of plaster of Paris 

 upon vegetation is very surprising, and has not been satis- 

 factorily explained, as the sulphate of lime is very insoluble 

 in water ; but as the soil has been shown to be largely sup- 

 plied with ammoniacal salts, particularly the carbonate of that 

 alkali, and as these substances are known to react upon one 

 another, I have supposed that the result must be owing to 

 these chemical interchanges.] 



Gravelly Sands. Gravelly sands may also be used 

 for stiff clayey soils, but they do not yield such good 

 results as the chalks. They must also be applied in 

 greater quantities, that is to say, at the rate of fourteen 

 hundred cubic feet to the acre. 



Clayey Earths. When the vineyard is situated on a 

 parched, flinty, or chalky soil, the modification of it, by 

 means of clayey soils will also be an excellent plan. 

 But care must be taken not to use clays too stiff for 

 that purpose, as they would not mix readily with the 

 soil. They should be applied in the proportion of 1,400 

 cubic feet to the acre. 



If these chalks, gravelly sands and clayey loams are 

 saturated with nutritive principles, they will prove all 

 the better. Of this kind, are the chalky muds of roads, 

 sea-sands, clayey earths resulting from decomposed sods, 

 but all these will then act both as manures and modi- 

 fiers. 



[The removal of mere earthy matter, as a modifier of the 

 soils we have to cultivate, is attended with so great expense, 

 that such a course of improvement will very seldom be re- 

 sorted to with profit. Moving of earth is one of the most 



