sufficient to attack all the carbide added, however largo or small that
excess may be, no more, and, theoretically speaking, no less, acetylene
can ever be evolved than 26 parts by weight of gas for every 64 parts by
weight of calcium carbide consumed. It is, however, not correct to invert
the proposition, and to say that if the carbide is in excess of the water
added, no more, and, theoretically speaking, no less, acetylene can ever
be evolved than 26 parts by weight of gas for every 36 parts of water
consumed, as might be gathered from equation (2); because equation (1)
shows that 26 parts of acetylene may, on occasion, be produced by the
decomposition of 18 parts by weight of water. From the purely chemical
point of view this apparent anomaly is explained by the circumstance that
of the 36 parts of water present on the left-hand aide of equation (2),
only one-half, _i.e._, 18 parts by weight, are actually decomposed
into hydrogen and oxygen, the other 18 parts remaining unattacked, and
merely attaching themselves as "water of hydration" to the 56 parts of
calcium oxide in equation (1) so as to produce the 74 parts of calcium
hydroxide appearing on the right-hand side of equation (2). The matter is
perhaps rendered more intelligible by employing the old name for calcium
hydroxide or slaked lime, viz., hydrated oxide of calcium, and by writing
its formula in the corresponding form, when equation (2) becomes

CaC_2 + 2H_2O = C_2H_2 + CaO.H_2O.

It is, therefore, absolutely correct to state that if the amount of
calcium carbide present in an acetylene generator is more than chemically
sufficient to decompose all the water introduced, no more, and
theoretically speaking no less, acetylene can ever be liberated than 26
parts by weight of gas for every 18 parts by weight of water attacked.
This, it must be distinctly understood, is the condition of affairs
obtaining in the ideal acetylene generator only; since, for reasons which