1820.] the Atomic Theory. 208 



same conclusions. Hydrogen gas, when it unites with sulphur, 

 does not alter its volume, but merely its specific gravity ; conse- 

 quently the difference of specific gravity between hydrogen and 

 sulphuretted hydrogen gas will show the weight of sulphur in the 

 latter. The weight of hydrogen and sulphuretted hydrogen may 

 be obtained by comparing each with the common standard, 

 atmospheric air. 

 1-000* •.•0694t::30-5t:2-116§l-000||:M80**::30-5tt:35-990++ 



For as 1-000 : M80 :: 30-5 : 35-9900, from which subtract 

 2-1160 weight of pure hydrogen, there remains 33-874 weight of 

 sulphur. 



Sulphuretted hydrogen, therefore, is composed of 



Hydrogen 2-116 1 



Sulphur 33-874 16 



This shows that if sulphuretted hydrogen gas be composed of 

 an atom of sulphur united to an atom of hydrogen, the weight of 

 an atom of sulphur will be represented by 16, leaving out frac- 

 tional parts on both sides, for in chemical experiments, absolute 

 precision, or |he precision of calculation, is impossible. 



The weight of the atom of sulphur is found to be the same by 

 both processes, and our arriving at it, by different methods, 

 strongly corroborates the justness of the conclusion. Such 

 coincidences could not exist unless the inference were well 

 founded. 



19. The union of atom to atom is the mast energetic, because 

 in this, which is called a binary combination, each atom is 

 retained with the whole force of the other, the union of 1 a + 1 6 

 is the strongest ; if we have 1 « + 2 b, then 2 b will be retained 

 with only half the force of one, and 3 b with only one third of 

 that force. But in such combinations a will be retained with the 

 force of 2 b in the second, and of 3 /^ in the third ; accordingly 

 it is very difficult to separate a or unite it with a third body, 

 whereas it is usually very easy to separate a portion of b and 

 bring it into a new combination. In such cases the result of 

 experiment coincides exactly with the deductions of the theory. 



20. Where a compound cannot be decomposed without a 

 total separation of its constituents, the combination is that of 

 atom to atom ; such is water, which totally decomposes into 

 oxygen and hydrogen, without producing any intermediate sub- 

 stance, partially consisting of the same constituents. It is dif- 

 ferent with the carbonate and bicarbonate of potash, the second 

 of which contains twice as much carbonic acid as the first. The 



• Speci6c gravity of common air. + Specific graviiy of hydrogen gas. 



X WeighloflOOcubic inches air. ^ Weigtit of 100 cubic inch. Iiyclrogen. 



I Common nir. »• Specific gravity of sulphuretted hydrogeu. 



+ t Weight of 100 cubic inches air. 

 X X Weight of 100 cabic inch, sulphuretted hydrogen. 



