REVIEWS. 
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soils under almost identical climatic conditions, found that the ground was 
poisoned for clover in one case, and not in the other. They also assert, that 
when land is clover-sick the only remedy is to wait some years before 
repeating red clover upon it. Baron Liebig, after carefully analyzing all 
their arguments, thus states the real cause of the failure of the clover on 
the approach of spring : — 
“ There cannot be the slightest doubt about the reason of this decay : 
the exhausted subsoil had not received back any of the lost conditions of 
fertility, and thus the plants were starved as soon as they had passed 
through the arable surface-soil, and their roots were beginning to spread in 
the subsoil.” 
That the soil is not inexhaustible, is shown by reference to the condition 
of certain soils once virgin, like those of parts of the American continent ; 
and in regard to the ultimate result of all endeavours to enrich the soil by 
bringing the subsoil to the surface, the author writes : — 
“ The notion of our ignorant practical husbandmen, that the soil contains 
ample store of the elements of food to enable them to pursue their system 
of agriculture, is due partly to the excellent quality of the land, but also 
to their skill in robbing it. The man who attempts to gain money by 
filing the weight of one gold piece from a thousand, cannot plead, in 
extenuation, that it is remarked by no one ; but, if discovered, he is 
punished by the law : for everybody knows that the fraudulent act, 
repeated a thousand times, would ultimately leave nothing of the gold 
pieces. A similar law, from which, moreover, there is no escape, punishes 
the agriculturist who w r ould make us believe that he knows the exact 
store of available food-elements of his land, and how far it will go, and 
who deceives himself when he fancies he is enriching his field by 
bestowing on the arable surface-soil the matter taken from the deeper 
layers.” 
In another chapter we are shown, by reference to the experiments of 
Schoenbein ( vide Popular Science Review for October, p. 108), that 
the ammonia of soils is derived from the atmosphere, and that all the 
factories in the world would not supply the quantity required, were it 
otherwise. To any one who reads Baron Liebig’s work, the conviction is 
inevitable, that plants derive their mineral constituents from the soil, and 
their organic materials from the air ; that the action of ammonia salts as 
manures is merely a solvent one ; and that, in our country, we are every 
day robbing the earth of a quantity of inorganic salts which is never 
restored, and that, in consequence of this, serious results, painful to con- 
template, must eventually occur. The utilization of sewage is dealt with 
fairly, and the appendix description of Japanese methods in regard to 
this will be read with much interest. It is impossible, in so small a space, 
to do justice to so admirable a work as that of Baron Liebig ; and we can 
only console ourselves with the hope that the reader will be led to examine 
the volume for himself. The highest meed of praise is due to the able 
translator, who has certainly discharged his duty with more than usual 
care, and who is already so well known to the scientific world, that 
further comments on our part would be superfluous. Baron Liebig’s book 
recommends itself to every one interested in, not only the theory, but the 
practice, of agriculture. 
