4 HOW CROPS GROW. 



The first book in the English language on the subjects 

 which occupy a good part of the following pages, was 

 written by a Scotch nobleman, the Earl of Dundonald, 

 and was published at London in 1795. It is entitled: 

 "A Treatise showing the Intimate Connection that sub- 

 sists between Agriculture and Chemistry." The learned 

 Earl, in his Introduction, remarked that " the slow pro- 

 gress which agriculture has hitherto made as a science is 

 to be ascribed to a want of education on the part of the 

 cultivators of the soil, and the want of knowledge in such 

 authors as have written on agriculture of the intimate 

 connection that subsists between the science and that of 

 chemistry. Indeed, there is no operation or process, not 

 merely mechanical, that does not depend on chemistry, 

 which is defined to be a knowledge of the properties of 

 bodies, and of the effects resulting from their different 

 combinations." Earl Dundonald could not fail to see that 

 chemistry was ere long to open a splendid future for the 

 ancient art that always had been and always is to be the 

 prime support of the nations. But when he wrote, how 

 feeble was the light that chemistry could throw upon the 

 fundamental questions of agricultural science! The 

 chemical nature of atmospheric air was then a discovery 

 of barely twenty years' standing. The composition of 

 water had been known but twelve years. The only ac- 

 count of the composition of plants that Earl Dundonald 

 could give was the following: "Vegetables consist of 

 mucilaginous matter, resinous matter, matter analogous 

 to that of animals, and some proportion of oil. * * 

 Besides these, vegetables contain earthy matters, formerly 

 held in solution in the newly-taken-in juices of the 

 growing vegetable." He further explains by mentioning . 

 on subsequent pages that starch belongs to the mucil- 

 aginous matters, and that, on analysis by fire, vegetables 

 yield soluble alkaline salts and insoluble phosphate of 

 lime. But these salts, he held, were formed in the pro- 



