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431 
its onicc, and left tlie organism to mingle with the excvcmeuts, or escape as 
carlionic acid and water from the hmgs. At length all the inorijanic mutters 
will re-a]i])oar iu the voided products The animal organism has 
performed the ofiice of a mill. Grain was supplied. Instead of appearing 
as flour and bran, and the intermediate meal, it appears, after intervals of 
greater or less length, in soluble inorganic salts in the liquid excrements, in 
insoluble inorganic salts in the solid excrements, and in carbonic acid and 
water. Now, after biirninga plant, what remains? It contained, when grow- 
ing, carbon, nitrogen, hydrogen, and oxygen, as organic bodies, and water. 
It contained also, in variable proportions, common salt, potass, soda, magnesia, 
lime, iron, phosphorus, sulphur, and silica. The first four were expelled in 
the combustion. The remaining ingredients, for the most part, remained im- 
changed. Had the plant gone into the body of an animal, and in the course 
of its evolutions through the organism lost its carbon, hydrogen, nitrogen, and 
oxygen, the remaining ingredients would have been the same as before. In 
one case the plant would have been burned in the organism ; in the other, in 
a crucible. The ashes and the excrements are substantialhj the same. . . . Kight- 
soil and guano are the ashes of animal and vegetable organisms burned in 
animal bodies. They are the ashes of plants — the essential food of plants. 
Hence their value us manures." 
So much, then, for the consistency of the interpretations of 
other writers — English, French, German, and American — with 
the interpretations we have ourselves given of the Mineral 
Theory of Baron Liebig. And how, we would ask, are these 
interpretations consistent with those now claimed by Baron 
Liebig and his friends, namely, that " TAe Mineral Tlieorjj'" 
"throws upon the air, or upon the ingredients of the mamire uJiich 
are organic in their origin, the task of furnishing nitrogen to the 
plants " ? 
Baron Liebig shall answer for himself, whether it is upon 
the manure" that he throws " the task of furnishing nitrogen 
to the plant" This one quotation and we have done with these 
lengthy illustrations of Baron Liebig's views. In a letter to the 
Editor of the ' Revue Scientifique et Industrielle,' a translation 
of a part of which is given in the ' Farmer's Magazine,' vol. xvi. 
(1847) p. 511, from which we quote, Baron Liebig says : — 
" It has been demonstrated that ammonia is a constituent part of the atmos- 
phere, and that as such it is directly accessible and absorbable by all plants. 
If, then, the other conditions necessary to the growth of the plants be satisfied — 
if the soil be suitable, if it contains a sufficient quantity of alkalies, jphos- 
fhates, and sulphates, nothing will he wanting: the plants tvill derive their 
ammonia from the atmosphere as they do carbonic acid. We know well that 
they are endowed with the faculty of assimilating these two aliments, and I 
really cannot see why we should search for their presence in the manures we 
use The question of the necessity for ammonia in our manures 
resolves itself into the question of the necessity for animal manures, and upon 
the solution depends the entire future prospects of agriculture ; for as soon as 
we can dispense with bulky farm-yard manure, by the use of artificial prepara- 
tions, the productive power of our fields is placed in our own hands." ! 
Tiiirdly — Having shown what was the " Mineral Theory " ad- 
2 F 2 
