420 Afjricultural Cliemistry. 
" For if Mr. Lavves atlniit, that the iiiinei'al constituents are indispensable to 
phxuts, how can lie maintain that these very mineral constituents are rephice- 
ablo by ammonia, that is to say, that by means of ammonia we can altogether 
dispense with them ? " — lb. p. 89. 
Baron Lieblo^ is perfectly well aware, that the sentences he 
refers to, presupposed certain " preliminari/ conditions," and had 
reference simply to the sou7'ce of the mineral constituents of 
plants in the ordinary course of agriculture. For those who 
have not read our Papers, however, we may say, that any such 
insinuation as that here intended by Baron Liebig, is empha- 
tically condemned — not only by special sentences, such as those 
quoted above, but by the whole tenor of our writings — as Baron 
Liebig himself is well aware, if ever he have read them. 
But to return to Baron Liebig's comments on that state- 
ment of his doctrines which he " can no longer tolerate," he 
says : — 
" The concludinof sentence ascribes to me the assertion that the produce of 
land is proportional to the supply or diminution of the available mineral con- 
stituents. T/us / have never said." — Tb. p. 115. 
Compare this with the quotation already given : — 
" The crops on a field diminish or increase in exact proportion to the 
diminution or increase of the mineral substances conveyed to it in manure." — ■ 
Agricultural Chemistry, 3rd ed., p. 212. 
Again Baron Liebig says : — 
" With regard to the previous sentence, I find in my work only one passage 
in which I speak of the land of England in the sense understood by Mr. 
Lawes." — Principles, p. 115. 
And in reference to this point he also says : — 
" It is not difficult to refute the opinions of another, if we ascribe to him 
assertions which he has never made. 
" It never occurred to me to assert that the land of Great Britain was defi- 
cient in the substances which are found together in the ashes of the crops raised 
on it, or that, on a soil naturally fertile, rich crops might not be obtained for 
several successive years, ly the use of ammoniacal salts almie." — p. 116. 
Baron Liebig denies, then, that he has addressed himself to 
the resultant wants of agriculture as practised in Great Britain — 
that he has ever maintained that the fertility of our fields in- 
creases or diminishes in a direct ratio with the supply of mineral 
elements capable of assimilation — or that, it is in the mineral 
constituents, as collectively found in the ashes of the exported 
produce, that our soils are deficient relatively to other consti- 
tuents. 
We will now examine the foundation of these several assertions. 
And first in order to show, that it was not only agricultuue (as 
distinguished from normal vegetation), but that it was agriculture 
