74 THE SOIL. 



CHAPTER IX. 



THE SOIL. 



262. Of the vast interior of the earth nothing is known 

 with absolute certainty. We are acquainted with the 

 outer portion, the crust, only; and the geologists and 

 the chemists have been studying that very attentively for 

 many years. 



By this careful and continuous study, the crust of the 

 earth, together with the waters resting upon it and the 

 atmosphere enveloping it, is found to be made up of sixty- 

 one, perhaps- sixty-two or sixty-three, elements. Several 

 of these, when pure, are gases ; but all are found, usually 

 in combination one with another, in a solid state. Several 

 of them may possibly be hereafter found to be formed of 

 one and the same substance. 



263. All these elements, except twelve or thirteen, are 

 metals, more or less like iron, copper, lead, tin, mercury, 

 gold and silver. The greater part of them are found 

 only as ores, that is, combined usually with oxygen, or 

 with sulphur, carbon, or something else, and often look 

 ing like earths, which indeed they are. About thirty-four 

 of them arc found in very small quantities, and are 

 seldom seen except by chemists. 



264. Only a few, as &quot;gold, silver, copper, mercury, and 

 platinum, are found in their native state, in the earth, 

 in the condition of purity. Metallic masses and frag 

 ments of stone, called meteoric stones, or aerolites, are 

 sometimes seen to fall, and are always supposed to have 



