196 GENERAL SCIENCE 



was abstracted and built into shells by animals in tjie ocean. In due 

 time these shells, mixed with more or less of earthy sediment from the 

 waters, accumulated at the ocean bottom, and became compact. 

 Marble as calcium carbonate seems to have been subjected to much 

 heat caused, probably, by great pressure. 



Many of the ores of the metals are carbonates, and when these are 

 roasted in furnaces, just as when limestone is heated in kilns, great 

 quantities of carbon dioxide gas pass off into the air. Oxides are left. 



CaCO 3 is nearly insoluble in water. If there be CO 2 in the water, 

 forming with the water carbonic acid (H 2 CO 3 ), the solution occurs 

 much more freely. This is probably due to a change of the carbonate 

 into the bicarbonate of calcium whose formula is H 2 Ca(CO 3 ) 2 . This 

 dissolves much more readily than the carbonate. 



THE CHIEF AMONG METALS 



Without coal as a fuel the machinery of modern industrial 

 life would largely stand idle. It becomes equally apparent 

 upon reflection that without metals there would be few 

 machines to operate, and these necessarily of the simplest 

 type. Millions of the world's workers are engaged in operat- 

 ing machinery in mills, factories, shops, and foundries, or 

 in occupations dependent upon providing the raw material 

 for this machinery and in the transportation of its finished 

 products. Transportation by land and sea, the transaction 

 of business, the discharge of household affairs, and the carry- 

 ing on of agricultural pursuits without the aid of machinery 

 would mean a return to a semi-civilized state. 



Something of an idea of the importance of metals in every- 

 day life is gained through an attempt to list the articles and 

 conveniences made impossible by a prohibition of the use of 

 all metals. There would be no steam or gas engines, no 

 steamships or steam and electric railways, no printing presses, 

 no telegraph and telephone service, no suitable tools for the 

 artisan and builder, only the rudest and most primitive of 

 implements for farming and of conveyances in travel, no 

 airplanes and auto trucks, no heating plants and plumbing, 



