Agricultiu-al Clicmistnj. 
447 
tained ; and also, how strenuously lie lias endeavoured to show, 
that the increase of produce in our exj)eriments was due, not to 
the efficacy of the aminoniacal salts employed, but " to the total 
sum of the available or soluble nutritive mineral constituents 
present in the soil." But now for the other side of the question. 
Besides stating, as already pointed out (and in spite of his 
lengthened argument and summing up to the contrary), that the 
increase we obtained by manuring Avith ammoniacal salts alone, 
was only what theory plainly predicted, he says : — 
" When we remember that it is the object of scientific research to discover 
the cause of tlie efficacy of ammoniacal salts, we must not forget, in our in- 
quiries, that the increase of produce, ohUiined h/ the t(se of these suUi', is to he 
ref/arded in itself as a firmly established fact, which can in no way be affected 
by the views we may entertain as to its cause." — Principles, p. 98. 
The efficacy of ammoniacal salts in yielding an increase of 
produce, not only in our own experiments, but as a " firmly- 
established fact," is now then fully admitted. And as it was 
impossible, in the face not only of our own particular experi- 
ments, but of now generally recorded experience, to avoid this 
admission in some form, how is it that Baron Liebig brings this 
result into consistency Avith the theory which supposes the in- 
crease to be proportional to the soluble minerals present in the 
soil ? We could blush for Baron Liebig as we quote his words : — 
" In these experiments, tlii'ee portions of land were each manured, for seven 
years, with mineral mamtre (mineral constiti;cnts of the soil and ammoniacal 
salts) " 
And again, in the same page — 
" It follows from this, that farm-yard or stahle manure can he replaced in 
its entire effect hy mineral mamtre ; and not only replaced, for it can be, by 
the use of mineral substances alone (sulphate of ammonia and sal-ammoniac 
are mineral), surpassed in its fullest efficacy." — Principles, p. 90. 
Thus then " ammoniacal-salts," " sulphate of ammonia, and 
sal-ammoniac," are to be classed as mineral manures ! This is in- 
deed begging the whole question ! But a manoeuvre so transparent 
as this, would not even require notice, were it only addressed to 
the scientific reader. As it is, however, it is necessary to remind 
the uninitiated or unwary, that throughout the discussions on 
the subject of agricultural chemistry during the last ten or a 
dozen years, the term ''^mineral manure " has acquired an entirely 
technical significance, and that it has been employed to designate 
those constituents which, when assimilated by the plant, would 
remain as asli after its incineration ; and it has been used, empha- 
tically to distinguish such constituents of plants or manures, from 
the combustible or volatile portions — that is, from the nitrogenous 
or ammoniacal, the carbonaceous, &c. Indeed, we need not go 
far to establish, from the words of Baron Liebig himself, the re- 
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