OF AGRICULTURE. 9 



and beds of marl and muck ; to mingle composts, 

 and adapt them to special crops; to improve the 

 quality of grain and fruit ; and to rear and feed 

 stock in the best manner, farmers require at least a 

 degree of knowledge of chemistry* Nor can they, as 

 a class, much longer afford to be without it; for it 

 has always been found that the application of 

 scientific principles to any branch of industry puts 

 power into the hands of the intelligent, to drive 

 ignorance from the field of competition, 



As an illustration of the foregoing remarks, let us 

 examine one of the investigations of Dr, Sprengel 

 in reference to rust in wheat The close and long 

 continued researches of Dr. Sprengel led to the 

 conclusion that an excess of iron- salts, and especially 

 of the phosphate of iron, greatly favored the growth 

 of red-rust on the leaves and stalks of wheat, and 

 other cereals, A soil in the vicinity of Brunswick, 

 that did not lack drainage, but lime, was remarkable 

 for growing wheat and barley, always attacked, and 

 generally blighted, by rust. A quantity of this soil 

 was taken into a field generally free from this 

 ruinous parasite, to form an artificial soil fifteen 

 inches in depth. Wheat planted in this soil was 

 badly injured by rust, while that grown all around it 

 in the same field was free from the malady. Dr. 

 Sprengel, by careful analysis, found a fraction over 

 a half per cent, of the phosphate of iron in the soil, 

 with only a trace of lime uncombined with silicic 

 acid. As free lime will take phosphoric acid away 

 from iron, and indirectly convert iron into the 

 harmless peroxide, and at the same time produce a 

 1* 



