22 THE CREATION OF MATTER 



that can be obtained by physical. The atoms and 

 molecules of the elements are for the most part different. 

 In mercury and iodine at a certain temperature the 

 molecule and atom are the same ; the molecule, i.e., con- 

 sists of one atom. But in a volume of oxygen gas, of 

 hydrogen, nitrogen, chlorine, a molecule consists of two 

 atoms. The atoms of these substances refuse to remain 

 single. It is not good for them to be alone, and rock to 

 and fro in solitary activity. When they can find no 

 other atom to which to attach themselves, when all 

 around are atoms of their own likeness and family, they 

 fasten on and link themselves to each other. In a jar, 

 therefore, of these gases, the separate and independent 

 molecules are each composed of two atoms. Ozone is a 

 cluster of three atoms of oxygen. Phosphorus clusters 

 in four, arsenic in four, sulphur from 450 to 550 in 

 sixes. The atoms of mercury and of iodine at a certain 

 temperature mate not with each other, and in this all are 

 alike. The atoms of hydrogen mate in twos, wherever 

 hydrogen is found, and are followed in this by nitrogen 

 and chlorine. Oxygen rejoices in twos, and becomes 

 exhilarating in threes, and it is always so with it. All 

 phosphorus atoms are so constituted as to seek associa- 

 tion with each other in fours. Sulphur is hard to satisfy 

 with company, and its every atom shows the same covetous 

 or affectionate nature. How perfectly the atoms of sub- 

 stances are made alike in this respect for made we cannot 

 help concluding that they are ! 



Motions of molecules. In a volume of gas what are 

 the molecules doing ? Is each resting in its place ? When 

 a jar is filled with them, when they have had time to 

 settle after being conveyed into it, do they become still 

 and rest in one position 1 No, they continue in motion. 

 Every molecule in the jar is moving to and fro without 



