CHEMICAL MANURES. 37 



those, on the contrary, which our industry must furnish to the soil. 

 Further, by the aid of our experiments in burnt sand, and with only 

 chemical products, we have realized a theoretic scale of culture whose 

 progressive returns have shown us the laws which regulate vegetable 

 productions. By the light of this collection of ideas we were enabled 

 to conceive and to realize practical processes of analysis accessible to 

 all, whose testimony is of almost absolute certainty, and by means of 

 which we can always say what a land contains, what it needs, and 

 can consequently determine the nature of the agents to which we 

 must have recourse to fertilize it. 



In our next lecture we will follow the consequences of these prin- 

 ciples, and will occupy ourselves particularly with the returns to be 

 obtained in practice by the aid of chemical fertilizers. 



LECTUEE FOURTH. 



nENTLEMEN: It is true that phosphate of lime, potash and 

 \J lime united to an azotic matter are the agents, par excellence, of 

 vegetable production. Manure, which until now has been the agri- 

 culturist's sole means of increasing the fertility of the soil, ought 

 necessarily to contain all the four. 



Here are three analyses of manure. They fully justify this pro- 

 vision, for they all show the presence of azote, phosphoric acid, pot- 

 ash and lime : 



100 OF DRY MANURE 



from farm from farm from farm 



of of of 



Vincenues. Bechelbronn. Tbiergarten. 



Organic Elements. 

 Carbon ............... 



::":."' ..... 59 - 65 65 - 5 6467 



Azote .................. 2.08 2.00 2.56 



Mineral Elements. 



Phos.acid ............. 0.88 1.00 1.26 



Sulphuric acid ...... traces. 0.63 0.82 



Chlorine .............. 0.70 0.20 0.32 



Aluminum per ...... 



Oxideofiron ........ 0.68 2.03 1.51 



Lime .................. 5.23 2.83 3.70 



Magnesia ............. 0.32 1.20 1.88 



Soda ................... traces. 2.60 0.87 



Potash ................ 2.46 2.60 3.87 



Soluble silica ........ 1.45 22.13 6.25 



Sand .................. 25.66 22.13 10.77 



You see, besides the four terms of the complete fertilizer, the m 

 nure contains carbon, oxygen and hydrogen. 



