VAKIOUS MAN^URES. 127 



gen, 2d phosphorus, 3d potasshim, 4th calcium, that 

 are taken away, and must be returned, and any fertil- 

 izer to be Gomjylete must contain all of them in quan- 

 tities that vary with the soil and plant, and one that 

 does not contain them is imperfect, unless the wanting 

 chemical is in excess in the soil under consideration. 

 We have for this purpose various manures, which may 

 be divided in two classes, 1st organic, 2d mineral, these 

 are used singly or combined. 



1st. Organic. — The most important is the barnyard^ 



' Mr. George Ville gives the following composition for barnyard manure, it 

 being considered an average : — 



( Without value for plants as it is found in great abund- 



Water 80.00 \ • ^i, -i i • +i u +- • <. 



I ance m the sou, being the result oi rams, etc. 



I 13.29. Without value for plants; arise in sufficient 



Hydrogen 0.82 |- , , • ^i • i • 



•' =^ I abundance m the an' and rain. 



Oxygen 5.C7 J 



Silica 4.42 ^ 



Chloride 0.04 



Sulphuric acid 0.13 



5.23. In sufficient quantities in all soils, and thereby 

 form elements of but little value, and the returning 

 Uxide OI yon 0.40 of them is no longer necessary. 



Soda 



Magnesia 0.24 'J 



Nitrogen 0.41 ^ 



Phosphoric acid 0. 18 I 1-48. The soil contains these in very limited quantities, 

 Potassa 0.49 I and the return of them becomes necessary. 



Lime 0.56 J 



Total 100.00 

 This learned professor tells us that the 13.29 of carbon, oxygen, and hy- 

 drogen mentioned above represent undecomposed fibres that have become 

 black on account of the alteration that has taken place. Consequently the 

 only active principles form but 1.48 per cent, of the total, which can only 

 produce its effect after a given time. 



