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PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



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These analyses present many points of interest, from the fact 

 that they include examples of almost all kinds of soil. Most of 

 them, it is true, belong to the class of what are usually called 

 turnip soils, but among them are the heavy clay of Mr Swan- 

 wick's field, which might almost be used for making bricks, the 

 sandy soil of Dirleton, and the light, gravelly, and poor soil of 

 Snawdon. All the soils, with the exception of Mr Swanwick's, 

 were in good condition, and most of them had been long under 

 cultivation, and had been liberally treated, and yet, notwith- 

 standing this, there is very great difference in their natural pro- 

 ductiveness. Instances are found among them in which the 

 unmanured plots yield only two or three tons of turnips to the 

 acre, while the manured plots give four or five times this quan- 

 tity, and others in which the unmanured are not far behind the 

 manured plots. On examining the analyses, it seems pretty 

 clear that this is not always due to the chemical composition of 

 the soil alone, though this, no doubt, has its effect, but depends 

 to no small extent on its mechanical texture. This is certainly 

 the main cause of the small produce in Mr Swanwick's experi- 

 ments, where the stiffness of the soil was snch that no other 

 result could be expected in a season like that of 1866. On the 

 other hand, it is to be noticed that the nothing plots on Mr 

 Shirriffs field, which is a good clay loam, capable of producing 

 excellent crops of all kinds, yield less than those of Mr Hope's 



