254 BOARD OF AGRICULTURE. 



of real prog-ross, whicli was altogether lost sight of amidst the ruins 

 of their lofty expectations. Even those who take a more cautious 

 and sober view of the progress of agricultural chemistry, are apt to 

 be led into expectations greater than facts justify, by the extraor- 

 dinary progress which the application of chemistry has eflected in 

 some other arts ; such for instance, as the art of bleaching and tlie 

 manuflicture of soda, which chemistry, by one great stride, raised 

 from the state of primitive rudeness in which the}' had existed 

 almost from time immemorial, to one at least of comparative per- 

 fection. Such facts may lead us at first sight, to expect that the 

 application of chemistry to agriculture should be followed by equally 

 rapid results ; but a little further consideration seems to point out 

 a very material difference between such arts and the cultivation of 

 the soil. In such a case as the manufacture of soda, for instance, 

 and indeed in all those in which the application of science has pro- 

 duced the most marked results, the chemist has presented to him 

 for solution a definite and circumscribed problem, involving tlie 

 mutual relations of some three or four different substances ; and he 

 is able to trace the changes which the coal, common salt and lime 

 employed, undergo, from the commencement of the process through 

 each successive step, until the soda is obtained in the perfect state ; 

 but in the art of agriculture each question frequently involves, not 

 one, but many problems, connected with the highest and most 

 abstruse doctrines of the science, in which not merely chemical 

 forces, but the fir more recondite phenomena of life come into play, 

 and in which the investigations of the chemist are carried on, and 

 his conclusions tested under the influences of weather, climate and 

 many other perturbing causes. 



The extreme complexity of the problems with which agricultural 

 chemistry has to deal may be conceived from the fact,, that most 

 plants contain from twelve to fifteen different substances, all essen- 

 tial to their existence, the relations of which must be investigated 

 before definite views can be obtained regarding the changes which 

 go on in the organism of the plant. These relations, moreover, are 

 far more complicated than even the number of the elements alone 

 would lead us to suppose ; the single element of sulphur, for instance, 

 which does not constitute more than two or three parts in the thou- 

 sand of most plants, exists there in not less than three different 

 forms of combination, in each of which it is as essential to the plant 

 as those wliich form the great proportion of its bulk. Now, it must 

 be sufficiently manifest, that questions involving elements of such 

 complexity are not to be solved as rapidly or easily as the far 

 simpler problems of mineral chemistry ; and that not merely on 

 account of their superior complexity alone, but because, in the one 

 case, theoretical chemistry sets us far on our way towards the solu- . 

 tion, wliile in the other tliere is still a great gap to be filled up, a 

 whole mine of scientific fiicts to be worked out, before we are in 

 the condition to approach sufficiently near the comprehension of 

 these more complicated phenomena. In fact, the latter are not 

 questions of pure chemistry, but, are intimately interwoven with 

 vegetable physiology — so much so, indeed, that in many instances 



