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It niay be of much importance to the farmer to possess some know- 

 ledo-e of these elements and their office, both as constituents of the soil, 

 and of the plants growing upon it. They may be divided into two 

 classes, according to their office in the vegetable economy ; those which 

 go to make up the frame work of the several tissues ; among which are 

 silex, lime and magnesia ; and those which go to fill up the interstices of 

 these tissues, among which are the inorganic matters, phosphates, &c. 



We shall endeavor to give a simple statement of the characters of the 

 inorganic elements of plants, as they are found in the soil, and of their 

 office, both as constituents of the plant and of the soil. These will be 

 spoken of in the order in which they occur in the Table. 



In doing this, it is taken for granted that they, for whose benefit this 

 article is written, do not noAv know these materials, their characteristics, 

 their nature, or their use, cither in the plant or the soil. 



Silex. — Under this term are included those of silica and silicic acid. 

 This substance is well known to all farmers by the names of flint, quartz 

 and sand. We see a nearly pure form of it in the clear, transparent quartz 

 crystals, in the agates so common in our gravel, brought from the region 

 of Lake Superior. The fine grains in ordinary sandstone are particles 

 of silex. It exists abundantly in almost all soils. It is without color, 

 taste or smell, and cannot be melted alone by the strongest heat. As it 

 occurs in the state of flint, of quartz or sand, it is perfectly insoluble in 

 water, and scarcely soluble in the strongest acids. It combines with 

 potash, soda, lime and magnesia, and in this manner it forms a large 

 portion of what are called crystaline rocks, (granite, basalt, <fec.) By 

 the action of the air, and other agents, these silicates, as these rocks are 

 called chemically, undergo decomposition and the silica is separated 

 from them in a soluble form. Thus it is found in a considerable quantity 

 in the waters of many mineral springs ; and in nearly all the "raters 

 that rise from any considerable depth beneath the surface, or have made 

 their way through any considerable depth of soil. If this soluble form 

 of silica has been very thoroughly dried, and especially when it has 

 been much heated or ignited, it becomes again insoluble. It is only in 

 its soluble state that it can, to any extent, be taken up into plants. It 

 is, therefore, found in plants, for the most part, in the above combina- 

 tions. When plants, which contain this soluble form of silica, are 

 .exposed to any decomposing agent, or of any liquid capable of dissolving 



