In the first place, it will be assumed that no
loss of heat by radiation occurs from the walls of the generator;
secondly, the small quantity of heat taken up by the calcium hydroxide
produced will be ignored; and, thirdly, the specific heat of acetylene
will be assumed to be 0.25, which is about its most probable value. Now,
a hand-fed carbide-to-water generator will work with half a gallon of
water for every 1 lb. of carbide decomposed, quantities which correspond
with 320 grammes of water per 64 grammes (1 molecular weight) of carbide.
Of those 320 grammes of water, 18 are chemically destroyed, leaving 302.
The decomposition of 64 grammes of commercial carbide evolves 28 large
calories of heat. Assuming all the heat to be absorbed by the water, 28
calories would raise 302 grammes through (28 X 1000 / 302) = 93 deg. C.,
_i.e._, from 44.6 deg. F. to the boiling-point. Assuming all the heat to
be communicated to the acetylene, those 28 calories would raise the 26
grammes of gas liberated through (28 X 1000 / 26 / 0.25) = 4308 deg. C., if
that were possible. But if, as would actually be the case, the heat were
distributed uniformly amongst the 302 grammes of water and the 20 grammes
of acetylene, both gas and water would be raised through the same number
of degrees, viz.
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