2 



On Agricultural Chemistry. 



lished only in May last, given the result of his latest researches 

 in agricultural and physiological chemistry. 



Among other labourers in this important field of investigation 

 of late years we may state that one of ourselves was occupied 

 several years, prior to the appearance of the first editi<m of Pro- 

 fessor Liebig's work, in investigating the action of different che- 

 mical combinations when applied as manures to the most important 

 crops of the farm; and that since the year 1843 we have been 

 conjointly engaged in systematically inv'estigating the subject of 

 agricultural chemistry in a more extended sense than that alone 

 implied in the question of the action of special substances as 

 manures. 



In the course of this inquiry, the whole tenor of our results, 

 and also of information derived from intelligent agricultural 

 friends, upon every variety of land in Great Britain, has forced 

 upon us opinions different from those of Professor Liebig on some 

 important points ; and more especially in relation to his so-called 

 " Mineral Theory/' which is embodied in the following sentence, 

 to be found at page 211 of the third edition of his work on Agri- 

 cultural Chemistry, where he says " The crops on a field diminish 

 or increase in exact proportion to the diminution or increase of 

 the mineral substances conveyed to it in manure." 



It will be easily conceived, therefore, that it was with much 

 interest that we turned to those pages of the new edition of Baron 

 Liebig's * Letters,' which treat of the food of plants, in order to 

 ascertain how far the facts of the last few years had tended to 

 alter or modify his views on points wherein our own differed from 

 those which he had hitherto published. 



It was in reference to our opinions on the views of Liebig, as 

 given in the axiom already quoted, that Mr. Pusey, when giving, 

 in the last number of this Journal, a review of the progress of 

 agriculture during the last eight years, called attention to what he 

 regarded as conclusive evidence against those views in some of our 

 results, which had appeared from time to time in former Numbers ; 

 and it is in reply to these remarks of Mr. Pusey that Professor 

 Liebig has devoted a note of four or five closely printed pages in 

 the ' Letters,' just published, to an attack upon our experiments 

 and opinions, as set forth by Mr. Pusey in the article referred to. 



Of the vast importance, both in a scientific and practical point 

 of view, of correct ideas on the subject here at issue, a judgment 

 may be formed by the manner in which the Professor himself 

 speaks of his Mineral Theory," in the new edition of his ' Let- 

 ters.' Thus, at page 483, he says of the agriculturists of England, 

 that sooner or later they must see that in this so-called ' mineral 

 theory,' in its development and ultimate perfection, lies the whole 

 future of agriculture." 



