456 
Agricultural Chemistry. 
agricultural authority in Englanil, namely, by IMr. Lawcs. It refers to tlic 
growth of turnips. (Vol. xii. p. 34, and vol. viii. part 2, p. 26, et seq.y — 
Jfrinciples, p. 123-4. 
[In consequence of tlie great length of this Paper, we must 
content ourselves on this occasion with examining only one 
or two of Baron Liebig's criticisms on this point, in that detail 
which we had intended.] 
Baron Liebig attributes to us the assertion, that " phosphoric 
acid alone was found efficacious " in our experiments — a state- 
ment in direct contradiction to opinions strongly insisted upon 
throughout our Paper on turnip culture, from which in part he 
quotes. He considers the results obtained by large quantities of 
burnt bones and sulphuric acid, as demonstrating " the existence 
of a very unusual quality of soil " ; and having thus admitted the 
fact itself, he adds : — 
" But if we inquire into the reason why the credit of this striking result is 
given to the phosphoric acid, we lind that this is a sheei- faiiaj. Were any 
one to assert that, under the circumstances, it was the free sulphuric acid 
which produced the result, it would be difficult to disprove the assertion, as 
will be seen from the following calculation." — Principles, p. 125. 
He then goes on to assume, that we employed in the experiment 
in question, " as a minimum," 400 lbs. of burnt bones (and sul- 
phuric acid besides), every year, during eight successive years — 
or in all, 3200 lbs. of burnt bones ; more than enough, as he 
tells us, for fifty average crops of turnips. Now it so happens, 
that 3200 lbs. of burnt bones is a pure assumption of Baron 
Liebig's, as indeed he admits in a note ; but be does not the less 
on this account make liberal use of this assumed fact. The 
quantity of phosphate of lime used in tlie eight years was in 
reality more than a thousand pounds less than was supposed 
by Baron Liebig. Further on, after having pointed out the 
excess of phosphate added in tlie previous years, he says : — 
"It is impossible to believe that the effect, in the seventh year, under these 
circumstances, can have depended on the newly-added phosphoric acid, as 
3Ir. Lawes concludes.'' — //)., p. 12G. 
And again — 
"What conclusion would Mr. Lawes have come to, had he manured his 
land, for two years, only with phosphate of lime, and had added, in the six suc- 
ceeding years, 400 lbs. of sulphuric acid alone, and had he thus obtained the 
same produce, in eight years as if he had used 3200 lbs. of burnt bones?" — 
Ih., p. 129. 
Now it does so happen, that we have an experiment that will 
show, as far as such a point is susceptible of proof, that there 
was an action due to the large amount of phosphate of lime 
added to the soil, which could not be attributed to " free sul- 
phuric acid " in admixture with it ; and further, that a still 
greater excess of superphosphate of lime gave a further increment 
