32 THE INVISIBLE WORLD 



thing by which all worlds are saturated and in 

 which all worlds seem, as it were, to float. 



In the present state of knowledge the different 

 kinds of atoms, or chemical elements, are eighty in 

 number. They combine with one another to form 

 the different kinds of molecules according to their 

 relative weights. The atom of hydrogen is the 

 lightest. Take this as the unit of measure. Call 

 it one. The atom of carbon is six times as heavy 

 as the atom of hydrogen. The combining number 

 is therefore, 6. The atom of oxygen is eight times 

 as heavy, therefore its combining number is 8. 

 The atom of sulphur being sixteen times as heavy, 

 its combining number is 16. For a similar reason 

 the combining number of the atom of iron is 28; 

 of mercury, 100; of silver, 108. And so on to the 

 heaviest atom, which is bismuth. Its weight is 

 two hundred and ten times that of hydrogen. Its 

 combining number is therefore 210. 



In combining to form molecules, the atoms are 

 never broken. Only whole atoms, or multiples of 

 the same, combine with whole atoms. Molecules, 

 thus formed, give character to all the different 

 kinds and masses of matter in the universe. Two 

 atoms of hydrogen unite with one atom of oxygen 

 to form the molecule of water. All the water in 

 the universe is composed, and must be composed, 

 of just such molecules. Every molecule of all the 

 carbon dioxide in the universe is composed of ex- 

 actly three atoms two of oxygen united with 

 one of carbon. All the pure alcohol in the world 



