VAKIOUS MANTJEES. 



127 



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

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

 izer to he complete 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 : — 



Water 



Carbon 



Hydrogen 



Oxygen 



Silica 



Chloride 



80.00 



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

 \ ance in the soil, being the result of rains, etc. 



6.80 

 0.82 

 5.67 J 

 4.42 

 0.04 



I 13.29. Without value for plants; arise in sufficient 

 abundance in the air and rain. 



Sulphuric acid 0.13 



Oxide of iron 0.40 

 Soda 



Magnesia 0.24 



Nitrogen 0.41 

 Phosphoric acid 0.18 



Potassa 0.49 



Lime 0.56 



5.23. In sufficient qujlntities in all soils, and thereby 

 form elements of but little value, and the returning 

 of them is no longer necessary. 



1.48. The soil contains these in very limited quantities, 

 and the return of them becomes necessary. 



Total 100.00 

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

 drocen mentioned above represent nndecomposed 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. 



