The first products obtained contain ethers and impure alcohols, which
are collected in the reservoir, E.
When the first products have been thus introduced into the reservoir,
and it is ascertained by tasting that good alcohol is passing over,
the liquid produced is directed into the second boiler, F. The sliding
valve, operated by a screw having a very fine pitch, establishes a
communication between the refrigerator, C, and the second boiler, F. The
office of this valve we shall learn further on. This first rectification
is performed in a vacuum, for a system of metallic pipes connects the
entire apparatus with an air-pump, O. The temperature at which the
liquids shall enter into ebullition in the boilers, A A, may, then, be
regulated in advance.
The operations will be carried on with a more or less complete vacuum,
according to the nature of the products to be rectified. The distiller
will have to be guided in this by practice alone.
The good tasted products are received in boiler No. 2, F, and there
the liquids are submitted to the action of an almost absolute vacuum.
As we have before said, their temperature falls immediately and
spontaneously. The vapors which issue from this liquid contain almost
solely pure alcohol. The other substances, which passed over in the
first distillation, no longer emit vapors at temperatures ranging
between -10 deg.
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