The weight of the liquid which distills in the unit of time increases
with the deviation of temperature between the two receivers.
i. The weight of the liquid which distills in the unit of time is
constant for a same deviation of temperature between the receivers,
whatever be, moreover, the absolute temperature of the receivers.
k. The weight of the liquid distilled in the unit of time is
proportional to the active surfaces of the receivers; that is to say,
to the surfaces which are the seat of passage of heat through their
thickness.
l. The least trace of a foreign gas in the vapors left in the apparatus
throws the preceding laws into confusion, and checks distillation to a
considerable degree, especially at low temperatures.
Thus, water distilling between 100 deg. and 60 deg. will pass over as
quickly as that which is distilling between 40 deg. and 0 deg.. Absolute
temperature is without influence, provided every trace of air or foreign
gas be got rid of.
The distillatory apparatus should be provided with an excellent
air-pump, capable of preventing all those entrances of air which are
inevitable in practice.
The following is the industrial application that we have endeavored to
make of these theoretical views: The rectification of alcohols is one
of the most complex of operations; it looks toward several results
simultaneously.
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