COMPOSITIOV OF SOILS AND THEIR ACTION. 49 



brick or earthenware, but not for cultivation ; and 

 wliere the alumina amounts to forty parts in a hun- 

 dred, it has the effect of rendering the soil so steril 

 as to be unfit for agriculture. A great variety of 

 experiments were made by Tillet of Paris, in the 

 formation of artificial soils, and he found that the 

 alumina, if it greatly exceeded the other ingredients, 

 had a very unfavourable eflfect. The most fertile 

 mixture produced was composed of sand or silica 

 46 parts, alumina 16 parts, and carbonate of lime 37 

 parts. 



It would be reasonable to expect that these three 

 earths, so essential to the productiveness of soils, 

 should enter largely into the formation of vegetables 

 grown upon them. That such is the fact has been 

 abundantly proved by the experiments of Bergmann 

 and Ruckert ; and, what is more curious still, these 

 substances are found, with few exceptions, in about 

 the same proportions in which they exist in the best 

 natural soils. In the analysis of different plants and 

 seeds by these chymists, it was found that 100 parts 

 of ashes, obtained from the following substances, 

 well leached, and, consequently, freed from all their 

 soils and soluble matter, yielded in 



Ashes of wheat . 

 " oats 

 " barley . 

 " rye 

 " potatoes 

 " red clover 



These facts in relation to soils and their produc- 

 tions are of great consequence to the farmer ; and, 

 if borne in mind, would not only greatly assist the 

 purchaser of farms in making good selections, but 

 also materially aid the cultivator in ameliorating 

 and improving such lands as are already subjected 

 to culture. Nothing, scarcely, is more easy than to 

 ascertain whether sand, or clay, or lime preponder- 

 ates in a soil : and whether the circumstances of 

 II.— E 



