Biographical Account of the late John Dalto> 



85 



Thus Richter had the merit of showing that the saturating power of 

 acids and bases might be represented by numbers attached to them ; and 

 he showed how useful such numbers would be in determining the compo- 

 sitions and decompositions of compounds. It is true that the numbers 

 which he supplied were far from accurate ; but that was owing to the 

 imperfect state of experimenting. The only chemist who approached 

 accuracy in his analyses of the salts was Wenzel, and his results were almost 

 quite neglected and unknown. 



It was easy to extend the law of Richter to all combinations, such as 

 oxygen with metals, sulphur with metals, and oxygen with hydrogen, sul- 

 phur, carbon, <fcc. ; this was accordingly done by various chemists, par- 

 ticularly by Berzelius, who by assiduous experimenting, and repeating 

 his analyses with data rendered more and more accurate, succeeded in 

 showing that numbers might be affixed to every chemical substance indi- 

 cating the proportion of it which was capable of neutralizing the quantity of 

 other bodies indicated by the numbers attached to them. These were 

 published by him under the name of Synoptical Tables ; and after he 

 became aware of the view taken by Dalton, he called them Tables of 

 Atomic Weights. 



Mr. Dalton, about the year 1802 or 1803 was occupied with the analyses 

 of defiant gas and carburetted hydrogen. He found that, for complete 

 combustion, a volume of olefiant gas required three volumes of oxygen, 

 and that after the combustion there remained two volumes of carbonic 

 acid. Now, one of the volumes of oxygen combined with two volumes of 

 hydrogen, and formed water; while the other two volumes of oxygen 

 combined with two volumes of carbon, and formed two volumes of carbonic 

 acid. Hence a volume of olefiant gas is composed of H 2 -f- C* condensed 

 into one volume. 



Carburetted hydrogen gas, on the other hand, required only two volumes 

 of oxygen to consume it, and left only one volume of carbonic acid. One 

 of the volumes of oxygen combined with two volumes of hydrogen, and 



