MATTER 25 



weights. Oxygen, for example, unites with every 

 element except fluorine, and with most elements in 

 more than one proportion, and yet the amount of 

 oxygen in any compound is always its atomic weight, 

 16, or some multiple of this weight. This renders it 

 possible for the chemist to represent every compound 

 by means of a formula which contains a definite num- 

 ber of atoms. A formula, such as that of water, H2 

 O, shows the kinds of elements, hydrogen and 

 oxygen; the number of atoms of each element in the 

 molecule, two of hydrogen and one of oxygen; and 

 the relative weights of the two elements. The two 

 atoms of hydrogen weigh 2 and the one atom of 

 oxygen weighs 16. The weight of the molecule, H 2 

 O, is equal to the sum of the weights of its atoms — 

 2 plus 16 equal 18. We know therefore, by examin- 

 ing the formula that 2 /is of the weight of water is H 

 and 16 /i8 O. 



When we consider the countless number of com- 

 pounds that may be formed by the union of the sev- 

 enty elements, ranging from the molecule of only two 

 atoms up to the most complex molecules, which con- 

 tain a half dozen or a dozen elements and hundreds 

 of atoms, and find that in every compound the law 

 of combination according to atomic weights is ob- 

 served, the fact is marvelous. Who numbers the 

 atoms that they may combine? Who wheels them 

 into line by twos, by tens - or by hundreds and binds 

 them together? The power of the Infinite is upon 

 them, for they are infinitely perfect in their workings. 

 The hand that upholds and guides the earth and 

 planets and the countless worlds that revolve through 

 infinite space, guides the atoms of which all these 

 worlds are made. 



What a wide and marvelous range of functions has 

 been bestowed upon certain elements! Carbon is a 



