242 Dr. Thomson on the [Oct. 



Azote 0-875 or J-^ths of 1-0000 



Chlorine 2-25 or f fi-ths of 1-0000 



Now if we reckon 1-000 the weight of an atom of oxyo-en, 

 then an atom of each of the other three gases will be equal to 

 the preceding numbers multiplied by 2. 



The atom of hydrogen. 0-125 or 0-0625 x 2 



azote 1-75 0-875 x 2 



chlorine. . 4-5 2-25 x 2 



There cannot be a doubt that, reckoning the weight of an 

 atom of oxygen to be unity, that of the other three gases is just 

 double their specific gravities ; consequently a given volume of 

 oxygen gas contains twice as many atoms as the same volume of 

 hydrogen, azote, or chlorine. Of course when we compare 

 together the volumes of these gases, and wish to convert them 

 into atoms, we must reckon half a volume of oxygen, as equiva- 

 lent to an atom ; and one volume of hydrogen, azote, and chlorine, 

 to be an atom. Thus water is composed of half a volume of 

 oxygen gas imited to one volume of hydrogen gas. It is, there- 

 fore, a compound of one atom oxygen and one atom hydrogen. 

 In like manner protoxide of azote is a compound of half a volume 

 oxygen gas and one volume azotic gas ; it consists, therefore, of 

 one atom oxygen united to one atom azote. Deutoxide of azote 

 being formed of one .volume oxygen gas and one volume azotic 

 gas must be a compound of two atoms oxygen and one atom 

 azote. I^Iuriatic acid being a compound of one volume hydrogen 

 gas and one volume chlorine gas, and a volume of each of these 

 gases being equivalent to an atom, it is obvious that muriatic 

 acid is a compound of one atom hydrogen and one atom 

 chlorine. 



The specific gravities of steam, protoxide of azote, and ammo- 

 nia, are as follows : 



Steam 0-625 



Protoxide of azote 1-5278 



Ammonia 0-5900 



Or reducing them to what they would be supposing the specific 

 gravity of oxygen uiiity : 



Steam 0-5625 



Protoxide of azote 1-375 



Ammonia 0-53125 



If we multiply the first two of these last numbers by 2, and 

 the last by 4, the products will be the weight of the atom of each 

 of these gases ; for 



0-5625 X 2 = 1-125 = an atom of steam 



1*375 X 2 = 2-75 = an atom of protoxide of azote 



0-53125 X 4 = 2-125 = an atom of ammonia 



