438 
Agricultural Chemistry. 
mineral matter, lie obtained dnring six years a higher produce than from the 
same laud unmanurcd ; for theory i)lainhj 'predicts such a result" — Principles, 
p. 78— 
we ask, is not this again the condemnation by Baron Liebig 
himself of his own j^reviously insisted upon doctrines, as already 
shown in quotations from his works, and in other words in his 
letter to the editor of the ' Revue Scientijique et Industrielle^ 
namely, that, 
' if the soil he suitable, if it contains a sufficient quantity of alkalies, phos- 
phates, and sulphates, nothing will he wanting ; the plants will derive their 
ammonia from the atmosphere, as they do carbonic acid " ? (I) 
Aofain, with regard to the assertion, that the amount of mineral 
manure supplied in our experiments was so small in proportion 
to the whole bulk of soil, that it " could most certainly 
produce no effect, or, at the utmost, a very trifling one," we 
may answer — 
1st, That mineral manures, applied to a similar description of 
soil, and in no greater proportion to its total bulk, have most 
marked effects upon the growth of turnips and our leguminous 
crops. 
2ndly, That the same mineral manures, applied in the same 
proportion to the bulk of soil, have a distinct effect, even upon 
the cereals, when there is an abundance of anailahle nitrogen provided 
within the soil itself. 
Srdly, That salts of ammonia, and other compounds of nitrogen, 
applied in even less proportion to the bulk of soil, increase the 
produce of wheat in the particular soil in question, from that of 
agricultural exhaustion to that of high agricultural productiveness. 
Let us now see by what kind of reasoning Baron Liebig be- 
lieves that he can " convey to the reader the full conviction " that 
our own experiments not only contradict the conclusions " that 
the mineral constituents of wheat cannot by themselves increase 
the fertility of land," and " that the produce in grain and straw is 
rather proportional to the supply of ammonia," but that they are 
also the " strictest and most satisfactory proofs " of his oion 
opinions. 
Tliose of our results which he particularly brings under criti- 
cism with this view, are — 
1st, Those of the continuously unmanured plot ; and, 
2ndly, Those of a plot (10 a) which, after having had mineral 
manures in the first year, without yielding any practical increase 
of produce, had then ammonia salts only, for a series of years ; by 
means of which, a large number of heavy crops have been ob- 
tained. 
In Diagram L we have the results of these two plots, and those 
also of plot 10 h by their side, from the commencement of the 
