THE STORY OF NINETEENTH-CENTURY SCIENCE 



be also the relative weights of each of their respective 

 atoms. If one pound of hydrogen unites with five and 

 one-half pounds of oxygen (as, according to Dalton's 

 experiments, it did), then the weight of the oxygen 



JOHN D ALTON 



atom must be five and one-half times that of the hydro- 

 gen atom. Other compounds may plainly be tested in 

 the same way. Dalton made numerous tests before he 

 published his theory. He found that hydrogen enters 

 into compounds in smaller proportions than any other 

 element known to him, and so, for convenience, deter- 

 mined to take the weight of the hydrogen atom as unity. 



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