CHLORINE. 79 



dry gas, as will be obvious from the following 

 simple calculation. Let 



x = sp. gr. of dry chlorine gas 



a = sp. gr. of vapour at 60 = 0'00772 



p = 30 inches mercury 



f elasticity^of vapour at 60 = 0-524 



then 



f 



' + 0) = 2-47 



P 



The solution of this equation gives us x = 

 Thus it appears, that if Gay-Lussac made his ex- 

 periments at the temperature of 60, the true 

 specific gravity of his chlorine gas was 2-507. 

 If the temperature (as is most likely) was a few 

 degrees above 60, then the true specific gravity 

 of the gas would be exactly 2-5, and his experi- 

 ments would coincide with my own. 



We may therefore, without hesitation, adopt 

 2*5 as the true specific gravity of dry and pure 

 chlorine gas. 



As muriatic acid is a compound of equal 

 volumes of chlorine gas and hydrogen gas, and wei s hs 4>5 - 

 as these gases unite in no other proportions, we 

 cannot hesitate to consider muriatic acid as a. 

 compound of 1 atom chlorine and 1 atom hy- 

 drogen. The atom of chlorine, therefore, must 

 bear the same relation to the atom of hydrogen, 

 that the specific gravity of chlorine gas does to 

 that of hydrogen gas. But chlorine gas is 36 

 times heavier than hydrogen gas ; for 0-0694 x 



