164 THE HISTORY OF SCIENCE 



always combined in the same proportions, and that 

 when there was more than one combination the 

 quantity of the elements always had a constant rela- 

 tion, such as 1 to 2, or 1 to 3, or 1 to 4, he 

 explained this fact on the Newtonian doctrine of in- 

 divisible atoms; and contended that, the relative 

 weight of one atom to that of any other atom being 

 known, its proportions or weight in all its combina- 

 tions might be ascertained, thus making the statics 

 of chemistry depend upon simple questions in sub- 

 traction or multiplication and enabling the student 

 to deduce an immense number of facts from a few 

 well-authenticated experimental results. Mr. Dai- 

 ton's permanent reputation will rest upon his having 

 discovered a simple principle universally applicable 

 to the facts of chemistry, in fixing the propor- 

 tions in which bodies combine, and thus laying the 

 foundation for future labors respecting the sublime 

 and transcendental parts of the science of corpuscu- 

 lar motion. His merits in this respect resemble those 

 of Kepler in astronomy." 



In 1808 Dalton's atomic theory received striking 

 confirmation through the investigations of the French 

 scientist Gay-Lussac, who showed that gases, under 

 similar circumstances of temperature and pressure, 

 always combine in simple proportions by volume 

 when they act on one another, and that when the 

 result of the union is a gas, its volume also is in a 

 simple ratio to the volumes of its components. One 

 of Dalton's friends summed up the result of Gray- 

 Lussac's research in this simple fashion : " His paper 

 is on the combination of gases. He finds that all unite 

 in equal bulks, or two bulks of one to one of another, 



