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What is patent still distillation?
Unlike Malt Whisky, Grain Whisky is distilled in a
continuous operation in a Patent Still. This is
sometimes known as the Coffey Still, after Aeneas
Coffey, who developed it in 1831.
Steam is fed into the base of the analyser and hot
wash into the top. As the two meet on the surface of
the perforated plates, the wash boils and a mixture
of alcohol vapours and uncondensed steam rises to
the top of the column. The spent wash runs down and
is led off from the base.
The
hot vapours enter the rectifier at the base and as
they rise through the chambers they partially
condense on the sections of a long coil through
which wash is flowing. The spirit vapour condenses
at the top of the rectifier and is run off through a
water-cooled condenser to the spirit safe and on to
the spirit receiver. Once the spirit begins to be
collected it runs continuously until the end of
distillation.
Because of the rectifying element present in this
process the distillate is generally lighter in aroma
than most Malt Whiskies. It consequently has a
milder character and requires less time to mature.
What is the worm?
The worm and its surrounding bath of cold running
water, or worm-tub, form together the condenser unit
of the Pot Still process of manufacture. The worm
itself is a coiled copper tube of decreasing
diameter attached by the lyne arm to the head of the
Pot Still and kept continuously cold by running
water. In it the vapours from the still condense.
Fed by the still, it in turn feeds the receiving
vessel with the condensed distillate.
The worm is being replaced gradually by the more
modern tubular condenser.
What are low wines?
This is the name given to the product of the first
distillation in the Pot Still process of
manufacture. It is the distillate derived from the
wash and contains all the alcohol and secondary
constituents and some water. It forms the raw
material of the second distillation, which is
carried out in the Spirit Still. The feints and
foreshots are added to the low wines when the Spirit
Still is charged.
What is pot ale?
Pot ale, alternatively burnt ale, is the liquor left
in the Wash Still after the first distillation in
the Pot Still process. It is the residue of the wash
after the extraction by distillation of the low
wines.
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