J. E. TESCHEM ACKER'S REMARKS. 245 



The stones accompanying the soil have the same composition, 

 and suffer, annually, some small disintegration : from such dis- 

 integration soils are formed. 



Sand, (silica,) besides lightening too stiff a soil, is chiefly of 

 use to strengthen and stiffen the stems of plants, enabling them 

 to resist the wind : for this purpose, it must be dissolved by con- 

 tact with an alkali, (potash or soda). These are usually found 

 in clay, (alumina,) which, as an ingredient of the soil, or of the 

 compost heap, is invaluable, although it never enters into the 

 organization of the plant. When the chemist analyzes a min- 

 eral containing alumina, it is almost impossible for him to wash 

 it free from the alkaline substances, which he has used in his 

 analysis, or which were originally combined with it. It grasps 

 and retains them with the most invincible obstinacy. Clay, in 

 its natural, original state, is formed from the disintegration of 

 felspar, and is, therefore, always combined with notable por- 

 tions of potash and soda. 



The president had spoken highly, but by no means too much 

 so, of charcoal, as an absorbent of the useful part of manure 

 ammonia. He, himself, had experimented many years with 

 this substance, in various ways, and could amply confirm all 

 the president had said. Clay appeared to him, however, more 

 retentive than charcoal, certainly, more so as regards potash and 

 soda, and may be had where charcoal is hardly to be procured. 

 Clay, then, well pulverized by frost, is a most valuable addition 

 to the compost heap, and a soil containing a fair proportion of 

 clay may, by manuring, be rendered the most permanently rich 

 of any. A light soil, besides permitting the ammonia to be 

 drawn up into the atmosphere by the heat of the sun, also, al- 

 lows the valuable salts of the manure to be easily leached 

 through by heavy rains, and a soil with too much clay does not 

 permit them to mix freely, so that the roots of the crop can ob- 

 tain easy access to their nourishment. The farmer who studies 

 the nature of his soil, will, while manuring liberally, be able 

 to manure much more economically than one who knows noth- 

 ing on the subject. It is probable that much of the labor and 

 expense wasted in manuring some lands with lime and plas- 

 ter, as well as many of the differences of opinion on these ma- 

 nures, have been owing chiefly to ignorance on this subject. 



