430 
Agricultural Chemistry. 
Professor Hugo von Mohl, in his ' Principles of the Anatomy 
and Physiology of the Vegetable Cell,' says : — 
" Instead of refonning agriculture by his manures, Liebig has caused them 
to demonstrate the incorrectness of his theory of the nutritivn of vegetables." — 
English Translation, p. 80. 
Baron Liebig, in his ' Principles,' recently published (p. 
121-123), professes to wonder where Professor Wolff "has found 
what he calls the pure Mineral Theory ? " Dr. Wolff answers 
him as follows : — 
" As Baron Liebig does not seem to understand how I became acquainted 
with the so-called ^ pure Mineral Theory,' founded and even yet defended by 
him, I will enlighten him. By the Liebig Mineral Theory every one under- 
stands the idea which was to be practically carried out in the patent manure, 
namely, that when a soil has become exhausted by one or more crops, the 
mineral constituents necessary for the food of plants shall be restored to it in 
sparingly soluble compounds, and in such proportions as a chemical analysis 
of the crop would indicate. By means of the patent manure the same plants 
might be grown uninterruptedly on the same land, and a succession of abun- 
dant crops obtained." — Zeitschrift filr Deutsche Lanchvii-the, 4en Heft, p. 112 
(Translated). 
In America much discussion has taken place regarding Baron 
Liebig's views. But, to save space, we will only give one quo- 
tation in connexion with that country. In a letter to Professor 
Webster, Professor E. N. Horsford, whilst with Baron Liebig at 
Giessen, writes, under date May 1, 1846, as follows (we quote 
from the ' Genesee Farmer' of August, 1855) : — 
" You are aware that Boussingault has expressed the opinion, after a variety 
of experiments, that the value of manure is in near relation to its percentage 
of ammunia. Mulder has, you know, written much in support of the view 
that ulmic and humic acids, ulmates, humates, &c., in one form and another, 
minister largely to vegetation Liebig differs from them all He 
takes the position, that the sources of carbon and nitrogen are carbonic acid 
and ammonia in the air 
" It is obvious (from analyses of soils and rain-water) that the ammonia 
spread on fields in the ordinary distribution of barn-yard products is of no 
moment. The quantity with usual falls of rain greatly exceeds, in the course 
of a season, any conceivable supply by human instrumentality 
" But if, in the manure-heap and the liquid accumulaljons of the barn-yard 
transported to the fields, the ammonia be not the chief ingredient, or an im- 
jwrtaid one, to what are we to attribute the unquestioned value of stable pro- 
ducts and night-soil ? Professor Liebig has shown, that if plants be ma- 
niu-cd with the ashes of plants of the same species, as the grasses of our 
western country are when burned over in the fall, they are supplied with 
their natural food Let us consider what these ashes are, and 
what manure is. Herbivorous animals derive their nourishment from the 
vegetable kingdom exclusively, their food being grass, grain, roots, &c. 
Those, with their organic and inorganic matters, are eaten. A portion of 
them is assimilated, becoming bone, muscle, tendon, fat, &c. Another por- 
tion is voided in the form of excrementitious matter. In process of time the 
bones and tissue follow the same course. What to-day forms the eye, with 
its sulpluir, and its phosphorus, and carbon, &c., will have accomplished 
