From The Practical Distiller, by Samuel M'Harry of
Lancaster County, Pennsylvania, 1809

(reprinted by Raudins Publishing 2004)

"Art. VII: To make four gallons from the bushel"
begins on page 55, and he talks for a page and a
half about the virtues of a process that can increase
yield in the production of whiskey, quoting the
number "four gallons per bushel". This he considers
a good yield, having previously (p.37) mentioned that
through the use of good yeast, yield could be increased
from 1.5 gallons to 3 gallons to the bushel.

The actual description of the process he describes takes
up the greater part of one page, which I will summarize here:

Mash your grain in the method that yields the most whiskey, but
the day before you mash, set out a clean barrel, and
"when your singling still is run off, take the head off and
fill her up with clean water, let her stand half an hour,
to let the thick part settle to the bottom, which it will
do when settled, dip out with a gallon or pail, and fill
the clean hogshead half full, so that when you fill it up
with cool water, it will be about milk-warm, then
yeast it off..."

He then says to let this sit overnight and use it the
next day instead of cool water when cooling down the
warm mash to make it ready for yeast.

My first thoughts are that although this is not the
sour mash process as we know it, it does capture all of
the essential features of the sour mash.

The method definitely combines a bit of the previous
batch of whiskey with the current batch, which is
the popular notion of sour mash. According to the recipe,
1/3 of the barrel that contains the new batch will be
from the (diltued) remains of the previous batch.

Although he doesn't mention it, the liquid
that he adds to the new batch was undoubtedly acidic,
which (as we now know) has the effect of discouraging
bacterial growth. This would account for the increase
in yield that he reports, and is (in my mind) the
primary reason for the sour mash process.

The only susbtantive difference between his method
and the modern method is the time at which the sour water
is added. I would suggest that the modern sour mash
process has a rather practical side: when mashing, one
has the sudden need for a lot of water, preferably hot,
and if it's slightly acidic that wouldn't be bad either.
M'Harry never quite makes this connection, but prefers
instead to let his sit overnight with a bit of yeast in

A few historic bits for perspective:
The importance of micro-organisms, and the true nature of
yeast and bacteria, weren't clear until around the time
of Pasteur, roughly ~1850.
Until then, fermentation was though to be the result
of chemistry.
Modern chemisty didn't really come around to recognizing
the existence of atoms and molecules until roughly ~1900.
Modern "yeast cake" preservation of yeast for future
didn't happen until the late 1800s.
The "patent still" / "Coffey still" wouldn't be developed
until the ~1830s.
So all of these things would have been unknown to the
1809 distiller.

Tim Dellinger