If 2 l. of chlorhydric acid gas be analyzed, there will result 1
l. of H and 1 l. of Cl. The same relation exists between the
molecules and the atoms, and the reaction is:--

HCl = H + Cl.

Reverse the process, and 1 l. of H unites with 1 l. of Cl to
produce 2 l. of the acid gas; there is no condensation, and the
symbol is HCl. In seven volumes HCl how many of each constituent?

The combination of two volumes of H with one volume of S is found
to produce two volumes of hydrogen sulphide. Therefore two atoms
of H combine with one of S to form a molecule whose symbol is
H2S.

H + H + S = H2S.

What is the condensation in this case?

PROBLEMS.

(1) How many liters of S will it take to unite with 4 l. of H?
How much H2S will be formed?

(2) How many liters of H will it take to combine with 5 l. of S?
How much H2S results?

(3) In 6 l. H2S how many liters H, and how much S? Prove.