TUANSACTIONS OF SECTION B. 509 



nitroo-euous compounds, and the incombustible or mineral constituents ; whilst the 

 carbo^, hydrogen, and oxygen, of which the greater proportion of the dry substance 

 of the plant was made up, were at least mainly derived from the air and water. 



Perhaps I ought not to omit to mention here that, each year for ten successive 

 years, from ISOS^to 1812, Sir Humphry Davy delivered a course of lectures on the 

 ' Elements of Agricultural Ohemistrv,' which were first published in 1813, were 

 finally revised by the author for the "fourth edition in 1827. but have gone through 

 several editions since. In those lectures, Sir Humphry Davy parsed in review 

 and correlated the then existing laiowledge, both practical and scientific, bearing 

 upon agriculture. He treated of the influences of heat and light ; of the organisa- 

 tion of '^plants ; of the difference, and the change, in the chemical composition of 

 their different parts ; of the sources, composition, and treatment of soils ; of the 

 composition of the atmosphere, and its influence on vegetation ; of the composition 

 and the action of manures ; of fermentation and putrefaction ; and finally of the 

 principles involved in various recognised agricultural practices. 



AVith the exception of these discourses of Sir Humphry Davy, the subject 

 seems to have received comparatively little attention, nor was any important addi- 

 tion made to our knowledge in regard to it, during the period of about thirty years, 

 from the date of the appearance of De Saussure's work in 1804 to that of the com- 

 mencement of Boussingault's investigations.^ 



About 1834, Boussingault became, by marriage, joint proprietor with his 

 brother-in-law of the estate of Bechelbronn, in Alsace. His brother-in-law, M. 

 Lebel, was both a chemical manufacturer and an intelligent practical farmer, 

 accustomed to use the balance for the weighing of manures, crops, and cattle. 

 Boussingault seems to have applied himself at once to chemico-agricultural 

 research ; and it was under these conditions of the association of ' practice with 

 science ' that the hrst laboratory on a farm was established. 



From this time forward, Boussingault generally spent about half the year in 

 Paris, and the other half in Alsace ; and he has continued his scientific labours, 

 sometimes in the city, and .sometimes in the country, up to the present time. His 

 hrst important contribution to agricultural chemistry was made in 1836, when he 

 published a paper on the amount of nitrogen in different foods, and on the equiva- 

 lence of the foods, founded on the amounts of nitrogen they contained ; and he 

 compared the results so arrived at with the estimates of others founded on actual 

 experience. Although his conclusions on the subject have doubtless undergone 

 modification since that time, the work itself marked a great advance on previously 

 existing knowledge, and modes of viewing the question. 



In 1837, Boussingault published papers— on the amount of gluten in different 

 kinds of wheat ; on the influence of the clearing of forests on the diminution of the 

 flow of rivers ; and on the meteorological influences affecting the culture of the vine. 

 In 1838 he published the results of an elaborate research on the principles under- 

 lying the value of a rotation of crops. He determined by analysis the composition, 

 both organic and inorganic, of the manures applied to the land, and of the crops 

 harvested. In his treatment of the subject he evinced a clear perception of the 

 most important problems involved in such an inquiry ; some of which, with the 

 united labours of himself and many other workers, have scarcely yet received an 

 undisputed solutiou. 



Thus, in the same year (1838), he published the results of an investigation on 

 the question whether^ plants assimilate the free or uncombined nitrogen of the 

 atmosphere; and although the analytical methods of the day were inadequate to 

 the decisive settlement of the point," his conclusions were in the main those which 

 much subsequent work of his own, and much of others also, has served to confirm. 



As a further element of the question of the chemical statistics of a rotation of 

 crops, Boussingault determined the amount and composition of the residues of 

 various crops ;''also the amount of constituents consumed in the food of a cow and 



' Some reference should have been made in the text to the labours and writings 

 of Dr. Carl Sprenj^cl, late Professor of Agriculture at Brunswick, who made numerous 

 analyses of agricultural materials, and published numerous papers in connection with 

 Agricultural Chemistry, during a series of years, commencing about 1826. 



