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Agricultural Chemistrtj. 
or 2G91 lbs. of increase ; whilst the mineral plot (18) gives only 
2620 lbs. total produce = only 163 lbs. increase. 
In 1853, the plot which had previously ammonia only, has now 
only minerals ; and the one which had minerals only, has now 
only ammonia. And we have again with the ammonia 4773 lbs. 
of produce = 3001 lbs. increase ; and with the minerals only 
2533 lbs. of produce = 761 lbs. of increase. 
In 1854, the manures are again transposed; and this being 
a very favourable season, we have, with the ammonia, 7923 lbs. 
of produce = 4427 lbs. of increase, or nearly 2 tons ; and Avith 
the minerals only, 3915 lbs. of produce = 419 lbs. of increase, 
or more than 4000 lbs. jier acre less increase than with the ammonia 
salts. 
Lastly, in 1855, the manures being again transposed, so also 
is the relation of produce on the two plots — the ammonia plot 
giving 6265 lbs. of produce = 3405 lbs. of increase : and the 
mineral plot only 3059 lbs. of produce =199 lbs. of increase. 
Tracing the history of each plot separately, the increase over 
the unmanured plot is as follows: — Plot 17, with minerals and 
ammonia, in 1850, 3332 lbs. ; with the same in 1851, 2905 lbs. ; 
with ammonia only in 1852, 2691 lbs. ; with minerals only in 
1853, 761 lbs. ; with ammonia only in 1854, 4427 lbs. ; and 
Avith minerals only in 1855, 199 lbs. Plot 18 again, with 
minerals and ammonia in the first year, gives 3054 lbs. ; with 
ammonia only in the second year, 2864 lbs. ; with minerals 
only in the third year, 163 lbs. ; with ammonia only in the 
fourth year, 3001 lbs. ; with minerals only in the fifth year, 
419 lbs. ; and with ammonia only in the sixth year, 3405 lbs. 
of increase, in each case, over the unmanured plot. 
We ask then, do these results either contradict the assertions, 
" that the mineral constituents of wheat cannot hy themselves 
increase the fertility of land," and " that the produce, in grain 
and straw, is rather proportional to the supply of ammonia " ? — or 
do they "prove" what we " intended to disprove,^' namely, that 
the whole produce is proportional " to the total sum of the 
available or soluble nutritive mineral constituents present in the 
soil"? 
What the " Mineral Theory " of Baron Liebig, as developed 
in his previous writings, really was — how that " theory " was 
understood by others as well as ourselves — and how inde- 
pendent, according to it, our cultivated plants should be of 
available nitrogen supplied to the soil, if only they are liberally 
provided with their necessary mineral constituents — the reader 
is by this time fully aware. He has also seen, that in 
passages and arguments in Baron Liebig's recently-published 
* Principles,' this identical " Mineral Theory " is still main- 
