The following is a transcript of a sheet of paper dated 1818 in the Catherine Carpenter Family Papers at the Kentucky Historical Society. The first side has -
"Receipt for Distilling Corn Meal Sweet Mash, 1818
To a hundred gallon tub put in a Bushel and a half of hot water then a half bushel of meal Stir it well then one bushel of water & then a half Bushel of meal & so on untill(sic) you have mashed one bushel and a half of corn meal - Stir it all effectively then sprinkle a double handful of meal over the mash let it stand two hours then pour over the mash 2 gallons of warm water put in a half a gallon of malt stir that well into the mash then stir in a half Bushel of Rye or wheat meal. Stir it well for 15 minutes put in another half gallon of malt. Stir it well and very frequently untill (sic) you can bear your hand in the mash up to your wrist then put in three Bushels of cold slop or one gallon of good yeast then fill up with cold water. If you use yeast put in the cold water first and then the yeast. If you have neither yeast nor Slop put in three peck of Beer from the Bottom of a tub."

On back of paper -
"Receipt for Distilling by a Sour Mash
Put into the mash tub Six busheles (sic) of very hot slop then put in one Bushel of corn meal ground pretty course (sic) Stir well then sprinkle a little meal over the mash let it stand 5 days that is 3 full days betwist the Day you mash and the Day you cool off - on the fifth day put in 3 gallons of warm water then put in one gallon of Rye Meal and one gallon of malt work it well into the malt and Stir for 3 quarters of an hour then fill the tub half full of Luke warm water. Stir it well and with a fine sieve or otherwise Break all the lumps fine then let it stand three hours then fill up the tub with luke warm water.
For warm weather - five Bushels of Slop Instead of Six let it stand an hour and a half Instead of three hours and cold water Instead of warm.

A Receipt for Destilling (sic)
By Sweet and Sour Mash May 18, 1818"

Both of these recipes sound more like a modern definition of "sour mash".
Mike Veach