The Thump Keg Mystery: How a Doubler Gets Two Runs Out of One Firing

For thirty years one subject has been knocking at my door, and I mean that plainly, for the thing really does knock. You keep your own fire, your own kettle and your own copper worm, and so I lay the Thump Keg Mystery before you as one natural philosopher to another: why does a second chamber, set between the pot and the worm, give a better drink? I write from the log walls of Fort Wilkins on the Suncook Valley Turnpike in Pittsfield. The evening's run is dripping into the jar, and under the window Barnaby, my black bear, four hundred pounds of bad manners on a chain, is grunting over a pail of mash-bottoms and half a woodchuck.

The Knock in the Cooper's Shop

I first heard a thump keg when I was a boy of about eleven, delivering horseshoe nails to a cooper over in Barnstead. It was a warm night and the door was propped open. From the back of the shop came a sound like a big man knocking at a door. Thump. Thump. Thump. I took it for the sheriff, who had at last learned to knock politely, and that frightened me worse than any warrant could. The cooper laughed so hard he swallowed his chaw, and he coughed for a quarter hour before he could explain.

Look first at the common pot still, which is only a kettle with a lid and a pipe. You boil your fermented wash. The vapour rises, runs down the pipe into a copper worm sitting in cold water, turns back to liquid and drips into your jar. One trip through a plain pot gives you little, though. The first run comes off weak, cloudy and coarse. The old Scotch and Irish distillers called it low wines, and they ran it through the still a second time to bring it up to strength and sweetness. Two runs meant two firings, two days, and two cords of wood split with your own blistered hands.

Singlings, Doublings and Samuel M'Harry

Then some clever devil, whose hand I would gladly shake and whose teeth I would gladly examine, set a second vessel between the pot and the worm. The hot vapour runs down a pipe that reaches nearly to the bottom of this keg and bubbles up through whatever liquid waits there. At first that liquid is cool, so the bubbles collapse with a knock, and that knock gave the thing its name. As the keg warms, its charge comes to a boil and the knocking settles into a low, contented rumble, like Barnaby after a ham. The vapour leaving the top has now been boiled a second time, and it is stronger and cleaner for it. One firing gets you close to what two used to.

The old Pennsylvania rye men called the first spirit singlings and the second doublings, so the keg came to be called the doubler. In the mountains it is the thumper. In my house it is that damned keg, for I have barked my shin on it more times than I have barked at the tax man.

The farm distillers of the rye country understood all this well. In 1809 one Samuel M'Harry printed a book in Pennsylvania called The Practical Distiller, one of the first distilling books ever printed in this country. My copy is water-stained and keeps its place with a molar for a bookmark. The former owner of that molar paid for the extraction in rye. M'Harry wrote for farmers, plain men who wanted their grain turned into something that would travel over bad roads and fetch a fair price. That is the whole purpose of the doubler: more strength from less fire and less labour. A pot still without one is like a man with one boot. He will get there, but slowly, and he will complain the whole way.

The Assessor in the Barrel

Last autumn an assistant assessor came out from Concord. He was a narrow, damp fellow with a nose like a pickaxe, and he wore his measuring tape round his neck like a bishop's stole. He had been sent to measure my apparatus. I told him plenty of Pittsfield ladies had tried that and none came back with a satisfactory figure. He did not laugh. Concord men don't.

An empty doubler barrel sat out by my woodpile, a good oak keg with staves an inch thick, waiting on a new hoop. All week Barnaby had been working at his chain staple the way a boy works at a loose tooth. Just as the assessor bent to read the mark on my pot, the staple let go with a pop like a champagne cork. The bear came round the still-house at a lope, and the assessor did the one intelligent thing of his life: he dove headfirst into the empty doubler, tape, hat and all.

Barnaby had never met a barrel that squeaked. He sniffed it, got a noseful of government man, and gave it a nudge. We are on a slope here, and the barrel rolled toward the turnpike with the assessor inside going round like a pickled egg in a churn, crying Oh! God! Oh! Lord! Oh! Mother! at every turn. Barnaby galloped alongside, batting it like a cat with a spool of thread. It fetched up against the stone wall with a bang that cracked two staves. Barnaby put his snout through the split, found the softest thing inside, and bit. The scream set the Haddock boys' cows bawling a mile off.

I got the bear back on his chain with a ham hock and tipped the barrel up. The assessor came out white as lard, with blood running into his left boot. A piece of his britches the size of a dinner plate was gone, and about a pound of what lay beneath it. I laid him face-down across my anvil bench and poured raw spirit over the wound while he cussed in two languages and invented a third. Then I closed it with horsehair and a harness needle, eleven stitches, the first federal property I ever handled with tenderness. I pulled a loose bicuspid free of charge and paid his livery bill in my own stamped coppers, G. G. WILKINS, PITTSFIELD N.H. He never did measure my still. I reckon it was the first time the government ever fed anybody in Merrimack County.

Storm Whiskey and the Old Drum

Miss Clara Higgins came up the road to visit, a herbalist from the Blue Ridge of Virginia and a keeper of the old mountain words. In her country the thumper is the heartbeat of the holler, but it is a tattletale heartbeat. On a still night you can hear one knocking a mile up a hollow, so the revenue men learned to stand on a ridge in the dark and listen. Her grandfather's people ran only on summer nights when a thunderstorm rolled over the mountain, with the thumping hidden under the thunder. They called what came off on those nights storm whiskey and swore it held a little lightning.

Her Uncle Royal hollowed a chestnut log as big around as a rain barrel and banded it with green hickory hoops he bent himself. He called it the old drum. One night the mash foamed up, puked over, and plugged the line with hot slop. The pressure built until the drum let go like a field cannon. A hoop whistled across the holler and buried itself in a sourwood tree forty feet off. Royal sat two feet to the left of its path, and it took the end off his ear. The hoop stayed in that tree for twenty years, and every boy in the family was walked down at fourteen to see it and told: “That's what happens when your line's shut. A thumper's got to breathe.”

From Miss Higgins I have learned that boil-over into the line is the puke, and that a small box or keg set between pot and thumper to catch it is a slobber box. A man who has had too much of the doublings has been kicked by the thumper. Her great-uncle Asa waited until after two or three hard frosts, when the wild persimmons turned soft, wrinkled and sweet as sorghum, then mashed a bushel into his thumper. The vapour carried the fruit's flavour up and out, something like honey and something like Christmas pudding, and the neighbours called it possum sugar. One year cousin Jubal was impatient and used green fruit. The preacher took a nip for his throat on Saturday night, and on Sunday his mouth drew up like a drawstring bag halfway through the sermon on the prodigal son. The congregation called it the finest service they had sat through in thirty years.

Laying Out and Running the Train

Everything here is history and instruction. Making spirits to drink without a federal license is against the law of this nation, and I have two arrests and a bear to prove the government means it. With that said, here is the train, step by step.

First, the layout. From the pot's cap a copper line runs to a slobber box, which I recommend, and from there into the doubler. That inlet must reach nearly to the bottom of the keg. From the top of the doubler, above the liquid, an outlet runs to the worm, coiled in a flake stand of cold running water. The worm's tail is open to the air, and so the whole train must breathe from pot to jar. Seal the joints tight against leaks, but never stop up the passage. A thump keg sealed tight is no distilling apparatus. It is a Fourth of July cannon pointed at your own britches.

Second, fill the pot no more than about three-quarters full of wash, for wash foams as it boils. A pot filled to the lip will puke into your line, a plug starts there, and a burst follows the plug. Third, charge the doubler a quarter to a third full. Some use plain wash. Thrifty men use the tails saved from the last run, because the doubler boils the good alcohol back out of them. An apple man might use cider pomace. Fill it past a third and the vapour has too much to push through, the keg grows sluggish, and liquid is more likely to carry over into the worm.

Fourth, keep the fire low and steady, with dry hardwood split even. You are not shoeing a horse; you are coaxing a kettle. The knocking is cool liquid swallowing hot vapour. Let it work. Once the doubler's charge boils, the knock eases to a rumble, and the spirit leaves the worm stronger than any plain pot gives on a first run.

Fifth, and here men go blind and die: the doubler does not excuse you from the cuts. If anything it brings them on faster. Throw out the foreshots, every drop. The heads follow, smelling sharp like a varnish pot. Catch them in a row of small jars, never one big crock, so that you can smell each jar and find where the heads end and the hearts begin. The hearts are the clean, sweet middle you were after all along. When the spirit turns oily, dull and wet-dog-smelling, you have reached the tails; save them for the next doubler charge. Use small jars, trust your nose, and do not be greedy. A greedy distiller and a greedy dentist have killed about the same number of men.

Sixth, the copper. A copper doubler and copper line give the vapour more copper to touch on its way to the worm, which works on the sulfur stink, so the spirit is sweetened twice: once by the second boil and once by the metal. Watch every joint, for alcohol vapour is as flammable as a widow's temper. Never walk away from a running still, not for dinner, not for the privy, not for the moon, and not to chase a bear. Seventh and last, let the fire die and everything cool, then empty the pot and doubler and scrub the copper bright.

Ashes, Oak and the Loud-Thump Fallacy

Cletus 'Rabbit' Miller of Wilkesboro, North Carolina, my cousin by spelling, writes that his uncle swears the old-timers threw hickory ashes or red oak shavings into the thump keg to clean out bad heads. I struck him a coin while I considered the question. Hickory ash belongs in the soap kettle. Run water through it and you get lye. Put a fistful into a hot keg of mash that holds corn oil and sour acids, and you get caustic foam. The old man saw that foam rising and thought he was scrubbing the devil out, when what he had invented was soap, in the one place nobody wants to wash. A Buffalo Ridge man who tried the ash trick made spirit that the neighbours called Monday whiskey. Lye does nothing for bad heads. The only cure for bad heads is the cut.

The red oak holds a grain of truth. Oak gives up tannin and colour, and shavings in the doubler may send a little woody flavour along with the vapour, but that is flavour, not cleaning. If you want colour and oak taste, set a few charred oak chips in the finished jar and let them steep for a season. Shavings in the doubler are a carpenter's guess at a chemist's job.

Two myths remain. The first holds that the louder the thump, the stronger the shine. That is hogwash. The loudness depends on how hot the fire is, how deep the charge is, and how cool the keg still is. A loud thumper proves your fire is hot, just as a loud preacher proves his lungs are sound, and it says nothing of the spirit in either. The second myth has killed men: that sealing the keg tight builds pressure and so builds proof. Pressure does not make proof. Pressure makes shrapnel. As Miss Higgins put it: “Forty feet, into a sourwood tree. That's all I'll say.”

That is the whole mystery, neighbours: a second boil in a single firing, a heartbeat between the kettle and the worm. Keep your copper clean, your cuts honest, and your fire low.