CERAMIC WARE. 221 



been weighed in the aggregate, so to speak ; and with the 

 result of demonstrating that, were it composed wholly of 

 water, it would only weigh between one-fifth and one-sixth of 

 what it does now. This is almost confirmatory of the opinion 

 that the interior portions of the earth must be mainly com- 

 posed of metals. Metals, taken all in all, are the heaviest 

 bodies in nature ; but some metals are extremely light potas- 

 sium and sodium, for example so very light, that they swim 

 in water. Aluminium, concerning which I have already 

 spoken, is also a light metal. As for lithium, it, though un- 

 questionably a metal, is the lightest of all known solid bodies ; 

 and, wonder of wonders ! hydrogen, the very lightest of 

 known material things an attenuated invisible gas, of which 

 an imperial pint weighs not quite a grain and a half, is actu- 

 ally considered by most chemists to be a metal. 



In respect of the materials which constitute our planet's 

 accessible crust, philosophers have acquired tolerably accurate 

 information. That crust, together with all the beings, ani- 

 mal and vegetable, it bears together with the atmosphere 

 which surrounds it is known to be composed of no more 

 than sixty-five or sixty-six elements in various states "of mix- 

 ture and combination; about fifty-three of them being metals.* 

 The number seems inconsiderable. Even were these ele- * 

 ments in equal portions distributed throughout our globe, it 

 would seem a marvel that Nature's myriads upon myriads of 

 manufactured results (not to speak irreverently) should be 

 produced out of so few raw materials. But they are not 

 equally distributed. It has so pleased the Almighty Archi- 

 tect, that out of three simple bodies, at least four-fifths of the 

 accessible crust of this globe shall be composed. The three 

 elements which have been appointed to this high dignity 

 are oxygen, aluminium, and silicon. Let the names of these 

 three chosen elements never be forgotten. I shall have a 



* The exact number is not agreed upon by chemists. 



