140 Review of Essays on Calcareous Manures. 



" Thus lime, marl, and all the calcareous compounds employed 

 in agriculture, since they furnish to plants lime and its compounds, 

 which sometimes form half of the fixed principles of vegetables, 

 ou^ht also to be considered as aliments, or, which comes to the same, 

 as furnishing a part of the substance of vegetables. Thus, again, 

 wood ashes, pounded bones, burnt bones, which furnish to vegetables 

 the calcareous and alkaline phosphates which compose a sixth part 

 of the fixed principles of the stalks, and three fourths of their seeds, 

 ought well to be considered, and syrely are nutritive." 



" What thus particularly marks the distinction between the ma- 

 nures which improve the soil [amend emens) and those which are ali- 

 mentary (engrais) is, that the former furnish, for the greater part, 

 the fixed principles of vegetables, the earths and salts, the latter the 

 volatile matters which are abundantly diffused through the atmos- 

 phere, whence vegetables draw them by suitable organs : and what is 

 more remarkable, is, that the vegetable by receiving the fixed prin- 

 ciples of which it has need, acquires as we shall see, a greater ener- 

 gy to gather for its sustenance, the volatile principles which the at- 

 mosphere contains." — Puvis. 



# # # # * # # #.# # 



" The greater part of improving substances are calcareous com- 

 pounds. Their effect is decided on all soils which do not contain 

 lime, and we shall see that three fourths, perhaps, of the lands of 

 France are in that state. Soils not calcareous, whatever may be the 

 culture, and whatever may be the quantity of manure lavished on 

 them, are not suitable for all products, are often cold and moist, and 

 are covered with weeds. Calcareous manures, by giving the lime 

 that is wanting in such soils, complete their advantages, render the 

 tillage more easy, destroy the weeds, and fit the soil for all products." 



"These improving substances have been called stimulants; they 

 have been thus designated because it was believed that their effect 



consisted only in stimulating the soil and the plants. This designa- 

 tion is faulty, because it would place these substances in a false point 

 of view. It would make it seem that they brought nothing to the 

 soil nor to plants, and yet their principal effect is to give to both, 

 principles which are wanting." 



11 Thus the main effect of calcareous manures proceeds from their 

 giving on the one hand, to the soil the calcareous principle which it 

 does not contain, and which is necessary to develop its full action 

 on the atmosphere, and on the other hand, to vegetables the quantity 



