23 HOW CEOPS GROW. 



was published at London in 1795. It was entitled : " A 

 Treatise showing the Intimate Connection that subsists 

 between Agriculture and Chemistry." The learned Earl 

 in his Introduction remarked that "the slow progress 

 which agriculture has hitherto made as a science is to be 

 ascribed to a want of education on the part of the culti- 

 vators of the soil, and the want of knowledge in such au- 

 thors as have written on agriculture, of the intimate con- 

 nection 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 denned 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, no 

 Jonger than seventy-two years ago, 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 20 years' 

 standing. The composition of water had been known but 

 12 years. The only account 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 pro- 

 portion of oil. * * Besides these, vegetables contain 

 earthy matters, formerly held in solution in the newly 

 taken-in juices of the growing vegetable." To be sure he 

 explains by mentioning on subsequent pages that starch 

 belongs to the mucilaginous matters, and that, on analysis 

 by fire, vegetables yield soluble alkaline salts and insolu- 

 ble phosphate of lime. Bat these salts, he held, were 

 formed in the process *f burning, their lime excepted, and 

 the fact of their being taken from the soil and constituting 

 the indispensable food of plants, his Lordship was unac- 



