1 large calories are set free. It is not possible
yet to determine thermo-chemical data with extreme accuracy, especially
on such a material as calcium carbide, which is hardly to be procured in
a state of chemical purity; and so the value 28.454 calories
experimentally found by Lewes agrees very satisfactorily, considering all
things, with the calculated value 29.1 calories. It is to be noticed,
however, that the above calculated value has been deduced on the
assumption that the calcium hydroxide is obtained as a dry powder; but as
slaked lime is somewhat soluble in water, and as it evolves 3 calories in
so dissolving, if sufficient water is present to take up the calcium
hydroxide entirely into the liquid form (_i.e._, that of a
solution), the amount of heat set free will be greater by those 3
calories, _i.e._, 32.1 large calories altogether.
THE PROCESS OF GENERATION.--Taking 28 as the number of large calories
developed when 64 grammes of ordinary commercial calcium carbide are
decomposed with sufficient water to leave dry solid calcium hydroxide as
the by-product in acetylene generation, this quantity of heat is capable
of exerting any of the following effects.
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