260 FIXED ALKALIES AND ALKALINE EARTHS. 



Sulphuric acid 5 

 Soda . . 4 



9 

 Atomic ]pj ve being the.atomic weight of sulphuric acid, 



weight of L 



and the salt being neutral, 4 must be the atomic 

 weight of soda. 



2. The atomic weight of soda being known, 

 it is easy, from the experiments of Gay-Lussac 

 and Thenard, to determine its composition, and 

 to deduce the weight of an atom of sodium. 

 100 grains of sodium, when plunged into water, 

 Atom of were immediately converted into soda, while 

 198*3 cubic inches of hydrogen gas were evolved. 

 From this experiment, it follows, that when 100 

 grains of sodium are converted into soda, they 

 combine with 99*15 cubic inches of oxygen gas, 

 or 33-6 grains. This experiment gives us the 

 composition of soda as follows : 



Sodium 100 or 2-976 

 Oxygen 33-6 - 1 



3-976 



We see that soda is a compound of 2 -976 of so- 

 dium and 1 of oxygen ; or of 1 atom sodium and 

 1 atom oxygen. The atom of sodium, by this 

 experiment, is 2*976, and the atom of soda 3*976. 

 This is a little below the truth ; for we have just 

 seen that the true atomic weight of soda is 4 ; 

 but the experiment is sufficient to satisfy us that 



