202 
CULTURAL CHEMISTRY. 
that would not be prudently contemplated by an individual. " I can assure you," 
said Mr. Johnston, " that ten long and laborious lives will be insufficient to complete 
the researches, which the inquiry concerning the variable proportions of nitrogen in 
crops, and the causes of such variation, requires." 
The gardener, up to the present period, has not much to lament the paucity of 
experimental discoveries heretofore made in his profession by chemical researches. 
If, as is the fact, it stands on record that, in respect to the comparative products of 
the farm (which, in point of numbers, do not amount to a thousandth part of those of 
the garden and its appendages), " the differences in the natural produce of different 
parts of the same field," are so great as to warrant the unconditional rejection of the 
whole, what could be expected were a similar course of analytic experiments applied 
to the soils, and productions attached to Horticulture ? We refer for a detail of 
tabular results to pp. 212 and 213, No. 21, August, 1848, of the Royal Agricultural 
Society's Journal. 
Some years ago, attempts were made by De Saussure, and others, to ascertain the 
phenomena of vegetable nutrition, by the exposure of plants, or some portions of 
plants, to the agency of carbonic acid and other gases, inclosed in bell-glasses ; and 
conclusions were thence drawn, which led to the announcement of a theory that 
assumed the appearance of truth. We say the appearance, because assuredly no 
correct deductions could be arrived at under conditions so unnatural. Even in our 
glazed houses and pits, where the laps are open to some extent, and not closed with 
putty, plants are exposed to the influences of heat modified by artificial means, to 
light softened and altered by refraction, and to air at least checked in its course, and 
subject to perpetual alteration in its condition of moisture. In one word, it may be 
safely asserted, that we have no right to expect trustworthy answers, to questions 
propounded in a form totally at variance with the natural laws. It has been urged with 
great propriety, by a writer in the " Mark Lane Express " of Sept. 4th, that chemical 
science has never yet been applied as it ought to be, since the true science of 
Agriculture, and of culture in general, is that which points out to us most clearly the 
different laws of nature. 
Liebig's great work first appeared about the year 1839. It was the engine 
which publicly diffused the theory of vegetable nutrition by the absorption of 
carbonic acid gas, through the oscular pores of the foliage. The doctrine spread 
with railway speed. Its disciples sprang up like mushrooms, our Institutions and 
Agricultural Societies swarmed with lecturers, who it is to be feared propagated 
theories which they did not understand (when applied to the physiological structure 
of plants), which they themselves could not practically apply, and " which were 
so entirely at variance with all practice, and so unproductive of practical good, 
that the minds of many who were inclined to be favourable to Science, became 
prejudiced against it." 
And thus it is with everything that involves deep, and interesting inquiries in 
doubt and perplexity. The food of plants, and the channels through which that food 
