198 



MANURES. 



life, 

 fuppl 



Sect. X. 3. 5 



th the matter of heat, are to produce or preferve a du( 



bricity of the folids, and a due d 



the liquids, which they 



of fluidity of 



And laftly, for the p 



pofe of diffolving or difFufing in it other folid or fluid fubflances, and 



thus 

 tion. 



them capable of abforp 



circulation, and fee 



/ 



5 



The due irrigation of the foil is much attended to in drier and 



mer 



as in 



Italy 



Eo-ypt, 



is 



d fome parts of Ch 



where numerous canals, and aquedudls, have been dug through hills, 

 and carriecf over vallies, for the purpofe of watering the foil ; and 

 even in this colder and moifter climate the practice of flooding land 

 is coming daily into greater repute. For this occafional fufFufion of 



water 



land not 



fupplies Ample moifture for the purpofes 

 above mentioned in the drier parts of the feafons, but brings alono- 

 with it calcareous earth and azotic air from the nei^hbourine forinc^s. 



ther manures from th 



Calcareous earth may be deteded 



t 



m the water of all thofe fprings which pafs under or over ft 

 marie or limeftone, by dropping into them a folution of fait of 



of 



of fugar of lead in water, or of foap in fpirits of 



d a por 



of azotic gas was difcovered in Bath-water by Dr. Prieftley, and 

 Buxton- water by Dr. Pierfon. See Sedion XI. 3. i. Dr. Home 



d found by h 



thinks he difcovered 



of lime in hard water 



periments that it promoted the growth of plants in a much greater 



degree than foft water 



6. Another demand for water in agriculture Is to give a due penc 



trabiUty to th 



fo 



which otherwife in moft lituatfons becomes fo 



hard as to ftop the elongation of the tender roots of plants ; but the 

 cohefion of the foil may neverthelefs be too much diminifhed by o-reat 

 and perpetual moifture, fo as not to give fuflicient firmnefs to the 

 roots of trees. And befides this too much as well as too little water 

 may be fupplied to the generality of vegetables, m 



hich 



the land 



grow upon 



though there are aquatic and amphibious plants as w 



3 



aquatic 



