448 
Agricultural Chemistry. 
cognised distinction, in agricultural discussions, between the terms 
mineral, and ammonia or ammoniacal. Thus he says : 
*' The mineral constituents act, as is shown by the produce of the un- 
manured land, ^vithout any artiticial supply of ammonia." 
" The ammonia increases the produce only if the mineral constituents he 
present in the soil in due quantity and in an available form." 
" Ammonia is without cfi'ect if the mineral constituents are wanting. Con- 
sequently, the action of aniiiionia is limited to the acceleration of the action of 
the mineral constituents in a given time." — Princijiles, p. HG-7. 
" • • • The other is the action of sulphate of ammonia as a solvent fur 
certain important mineral constituents of the soil." — lb., p. 99. 
" Ammonia, when used as a mainu'e alone, and when there is a want of 
mineral constituents in the soil, is like the spirits which the labourer takes, in 
order to increase his available labour, power, or imagination." — lb., p. 106. 
It is needless to multiply quotations. The ruse, however, has 
not been entirely without success. For in public discussion 
of the subject at the late Meeting of the British Association, 
before Baron Liebig himself, one of his advocates stated, that 
the difference between Baron Liebig and ourselves rested mainly 
on a misunderstanding — on a different use of nomenclature— f or 
" salts of ammonia are mineral manures " This method of 
begging the whole question was, however, we were glad to find, 
entirely disallowed by mutual friends of Baron Liebig and our- 
selves with whom we conversed on the subject ; and we are 
glad to find, that writers of the agricultural press have also 
expressed their sense of this manoeuvre. Thus, in an able 
article on this discussion in the ' North British Agriculturist' 
(Nov. 7, 1855), the writer says — " Neither can we think him 
justified in claiming sulphate of ammonia and sal-ammoniac as 
mineral substances (' Princi})les,' p. 90), which is simply be(jf)inrj 
the loliole question at issue." 
But Baron Liebig has yet another way of claiming the neces- 
sarily admitted action of ammoniacal salts, as one of minerals. 
Thus he says : — 
" Now, since sulphate of ammonia and sal-ammoniac, in the same way as 
carbonic acid, increase the solvent power of water for these essential ingredients 
of the food of jilauts, the question at once arises, whether their good effects 
may not depend in great part on tliis jiroperty, and whether, in the experi- 
ments of Mr. Lawes, the whole effect of the ammoniacal salts do not consist of 
two actions, namely, that of ammonia, as food for j>lants, as a source of 
nitrogen, and that of its salts as replacing carbonic acid? The answer to this 
question may serve to reduce to its real value the assertion of Mr. Lawes (vol. 
xii. p. 24), ' that it would be much nearer tlie truth to say that the crop has 
risen and fallen in proportion to the diminution or increase of the aumionia 
supplied to it in manure.' " — Principles, ]i. 91-2. 
" But if, on the contrary', only a small part of the ammonia acted by its 
nutritive property, and hy far the greater part by its solvent jjower fov phos- 
phates and silicates, its action is explained in a more satisfactory manner ; for 
in this case the effect is proportional to the quantity of water which entered 
the plants, and was given off by evaporation from their surface, the solvent 
