30 THE CREATION OF MATTER 



combination, constituted it. Chlorine, a yellow gas of 

 suffocating properties, and sodium, a metal of white 

 colour, combine to give us common salt. Who would 

 imagine beforehand that water is composed of two light 

 gases. In every case of real and perfect combination 

 the qualities of the constituents are lost, and seem to be 

 even destroyed, so entirely have they disappeared. Even 

 when the same elements combine in different proportions, 

 the resultant compounds are as unlike as any others, and 

 are separated by a wide gulf. 



The laws of chemical combination suggested to Dalton 

 the atomic theory of the constitution of matter, which 

 he propounded a century ago. He deduced it from the 

 laws of definite and multiple proportion. He found that 

 when one element enters into combination with another, 

 it is always in the ratio of 1 to 1, or 1 to 2, 1 to 3, 1 to 4, 

 or 2 to 3, to 5, to 7, etc. From this he concluded that 

 the elements consist of atoms which unite in definite and 

 fixed numbers to form compound molecules. This theory 

 has held the field for a century, and still holds it. 

 Modifications may await it in the future, but, as we shall 

 see, they can only be in the direction of order, and there- 

 fore not of a nature affecting our argument. 



In chemical combination, when two or more different 

 kinds of atoms are brought together in appropriate cir- 

 cumstances, they close together, they form a new molecule, 

 revealing new qualities. And in the same circumstances, 

 the myriads of the atoms of the one combine with the 

 myriads of the atoms of the other. Between the two 

 kinds of atoms there exists a chemical attraction or 

 affinity which produces the results. For illustration, a 

 few examples may be presented. Hydrogen and oxygen 

 are gases consisting of atoms : mix them together and 

 introduce a burning taper ; an explosion takes place, and 



