322 Agricultural and Horticultural Chemistry. 



The second stage of these experiments was to improve 

 or alter the quality of the produce, by the application of 

 those substances, which were found to have been absorbed 

 from the soil in the largest quantities. In the course of the 

 experiments, many mteresting facts have been ascertained 

 worthy of record. 



The recent labors of chemists in Europe have done much 

 to lay a foundation and form a practical system of agricul- 

 tural and horticultural chemistry. Considering the little 

 attention, previous to their labors, bestowed on the subject, 

 and the numerous ill understood facts, until a very recent 

 period, which hung around it, it is snrprisiog to notice the 

 benefits which chemistry has already conferred on the pro- 

 cesses of cultivation, as connected with vegetation: and 

 the beneficial results which have been made known in such 

 a short time. The great sources of the food of plants have 

 been traced out and determined ; the manner in which they 

 obtain the various elements necessary to their growth has 

 been investigated, and attention has been drawn to the 

 importance of the inorganic substances alwa^^s present in 

 plants. Liebig has more especially drawn attention to the 

 necessity of supplying these substances to growing plants, 

 as well as those which, more properly speaking, constitute 

 their food, viz., such as supplying them with carbon, oxy- 

 gen, hydrogen and nitrogen, the four elements, which, by 

 entering into combination with each other, in different pro- 

 portions, give rise to the formation of woody fibre, gluten, 

 starch, gum, and all the various proximate elements of 

 plants, and which, consequently, compose the whole of 

 their organic structure. I shall now select a passage or two 

 from Mr. Solly's report to the chemical committee, wherein 

 he endeavors to trace out the sources of those elements 

 which give rise to the formation of all vegetable produc- 

 tions, and cannot do better than give it in his own v.-ords: — 



" Much has been written on the source of carbon, and 

 the state it must be in, to enable it to enter into the organs 

 of plants, and assist in their growth by undergoing assimi- 

 lation. It was long ago believed, by Drs. Priestley and 

 Ingenhousz, as well as other observers, thai plants derive 

 the carbon which they contain from the carbonic acid al- 

 ways present in the air. They observed that it was impos- 

 sible for the carbon contained in a large tree, for example, 

 to have been derived from the soil, because the space of 



