470 
Agricultural Chemistry. 
Ammonia salts — generally an equal mixture of the sulphate 
and muriate. 
As already stated, the crops brought into this review, are 
wheat, barley, beans, clover, and turnips. In the case of wheat, 
barley, and beans, the figures rejnesent the total increase, in- 
cluding both corn and straw ; in that of clover the increase is 
given for the sake of comparison, in somewhere about the 
same state of dryness as the corn crops, that is, to the weight 
of the drt/ matter, one-sixth is added for water : and that of turnips 
includes both leaf and bulb in the fresh state as weighed. 
At an earlier page, we have called attention to the fact, that 
Baron Liebig being obliged to admit the influence of nitro- 
genous manures in yielding an increase in wheat in the experi- 
ments on our own land, asserts that such a result is simply ex- 
ceptional ; and that from it no conclusion can be formed as to 
what would happen on any other lands of different quality. On 
this point he says : — 
" Had Mr. Lawes asserted, that on his land, in the given circumstances, 
ammonia and ammoniacal salts were found to be jieculiariy favourable to the 
growth of wheat ; and that, leaving the price out of view, these salts, under 
similar circumstances, formed the best manure, he would simply have con- 
firmed a result predicted by theory. But even if his assertion had been given 
as an entirely new discovery, there could have been nothing tirged against it. 
" If, however, we extend his conclusions to any other land of different 
quality, and placed in different preliminary conditions, it will appear entirely 
erroneous ; for it can be proved, in the same way, and by facts equally de- 
cisive, that ammoniacal salts alone, in thousands of wheat-fields, do not in the 
smallest degree increase the produce ; and that, in thousands of other such 
fields, these salts do increase the produce for a year, or for two years, and that 
then a farther application of them to the same land is foitnd to be utterly 
without effect." — Principles, p. 79, 80. 
" The results of Mr. Lawes have no value for his next-door neighbour, nay, 
they have no value for himself; for the recipe, to which he comes, only 
applies to his own lands, and to them only in so far as experimented on, and 
only for a very limited number of years." — Ih., p. 105. 
" It is altogether incompi'ehensible that it should never for one moment 
have occurred to Mr. Lawes, that in Germany, France, and even England, all 
land has not the quality of his land." — Ih., p. 120, 
Now we have already shown, that whatever the natural quality 
of our own land, and whatever the amount of its annual produce 
under the influence of natural soil and season supplies, it was 
nevertheless, in an agricultural sense, in a state of corn-exhaus- 
tion, induced by the growth of a succession of crops in the 
ordinary course of farming, but without receiving any manure 
after the commencement of the course. It was, indeed, brought 
into such a state, that its produce was very far below that which 
might have been obtained by the ordinary means of restoration. 
We further maintain, that the nature of the exhaustion which 
the results of these experiments showed our field to have un- 
