114 PHYSIOGRAPHY. [CH. vii. 



in so delicate an experiment ; but, in the hands of modern 

 chemists, it has yielded the most trustworthy results which 

 we possess on this subject. These results agree substan- 

 tially with those which have been stated before. Indeed 

 there is no fact in the whole range of chemical science 

 better established than this, — that water is a definite 

 chemical compound of oxygen and hydrogen, in the pro- 

 portions by weight and measure previously given in this 

 Chapter. 



And thus we arrive at the last word of science, in its 

 present state, respecting the origin of the river Thames. So 

 far as its flood is pure water, we can trace that water to the 

 ocean. And the pure water which forms the chief com- 

 ponent of the sea has certainly been formed, some time or 

 other, by the union of two bodies, oxygen and hydrogen, 

 which, in their free state, are known only in the physical 

 condition of gases. 



