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MISCELLANEOUS COMMUNICATIONS AND 
NOTICES. 
7. — Mr. J. B. Lawes and the Mineral Theory. 
By Baron Liebig. 
In the last number of the ' Journal of the Royal Agricultural 
Society of England,' published in 1863, there is a paper by Messrs. 
Lawes and Gilbert, in which old charges against roe, personal and 
others, are revived ; and as they have sent an extract from that 
paper to all the Universities, Agricultural Colleges, and Journals 
in Germany, as well as duplicates to myself, it is evident that 
they attach a great value to their statements, and in order to give 
others the means of judging them correctly, I think it advisable 
to answer them. 
In my ' Principles of Agricultural Chemistry ' (p. 90, 1855), I 
had called Messrs. Lawes and Gilbert's attention to the fact that 
their experiments included the proof that farmyard-manure 
(organic manure) could be entirely replaced by mineral manure 
(for sulphate of ammonia and sal ammoniac are mineral) ; and, 
therefore, so far from refuting my doctrine, they had really sub- 
stantiated it. To this they replied that ammoniacal salts belonged 
to the class of organic manure; that I had always considered them 
as such ; and that in falling back on the strictly scientific mean- 
ing of the terms mineral and inorganic, I was begging the 
question ; was trying by a manoeuvre or ruse to give a new defi- 
nition to my mineral theory, or rather to substitute for it another 
which was not my own. Although I tried to convince them by 
a paper printed in the 'Journal of the Royal Agricultural Society 
of England ' (1856), that I never had considered ammoniacal salts 
an organic manure, they return to their accusations now, and 
endeavour to support them by quoting the following passages of 
my works : — 
" But the weight or amount of the crops is in proportion to the quantity of 
food of both kinds, atmospheric and mineral, which is present in the soil, or 
conveyed to it in the same time. By manuring with ammoniacal salts a soil 
rich in available mineral constituents the crops are augmented in the same 
way as they would have been if we had increased the proportion of ammonia in 
the air." — Principles, pp. 77-8 (1855). 
" The mineral constituents act, as is shown by the produce of the unmanurcd 
land, without any artificial supply of ammonia. 
" The ammonia increases the produce only if the mineral constituents be 
present in the soil in due quantity, and in an available form. 
"Ammonia is without effect if the mineral constituents are wanting. Con- 
