AND OF THE OTHER BODIES OF SPACE. 19 



vaporiform. We are the more entitled to draw such conclu- 

 sions, seeing that there is nothing at all singular or special in 

 the astronomical situation of the earth. It takes its place 

 third in a series of planets, which series is only one of num- 

 berless other systems forming one group. It is strikingly 

 if such an expression may be used a member of a democracy. 

 Hence, we cannot suppose that there is any peculiarity about 

 it which does not attach to multitudes of other bodies ; in 

 fact, to all that are analogous to it in respect of cosmical ar- 

 rangements. 



It therefore becomes a point of great interest what are the 

 materials of this specimen ? What is the constitutional cha- 

 racter of this object, which may be said to be a sample, 

 presented to our immediate observation, of those crowds of 

 worlds which seem to us as the particles of the desert sand- 

 cloud in number, and to whose diffusion there are no con- 

 ceivable local limits ? 



The solids, liquids, and aeriform fluids of our globe are all, 

 as has been stated, reducible into fifty-five substances hitherto 

 called elementary. Of these, forty are well- characterized 

 metals, twelve non -metallic bodies, and the remaining three 

 solid substances of intermediate character, which form a con- 

 necting link between the two great groups. Among the non- 

 metallic elements, four viz., oxygen, hydrogen, nitrogen, 

 and chlorine, are permanently gaseous ; bromine is fluid at 

 common temperatures ; and the remainder (with the ex- 

 ception of fluorine, which has never been isolated, and whose 

 physical characters are consequently unknown) are solid. 



The body oxygen is considered as by far the most abun- 

 dant substance in our globe. It constitutes a fifth part of 

 our atmosphere, eight-ninths of the weight of water, and a 

 large proportion of every kind of rock in the crust of the 

 earth. Hydrogen, which forms the remaining ^part of water, 

 and enters into some mineral substance, is perhaps next. 

 Nitrogen, of which the atmosphere is four-fifths composed, 

 must be considered as an abundant substance. The metal 

 silicium, which unites with oxygen in nearly equal parts to 

 form silica, the basis of about a half of the rocks in the 

 c2 



