From an unknown 19th century distiller, here’s
To make gin out of apple whiskey
Fill hogshead of 100 or 120 gs. [gallons] with apple whiskey, into which pour a bushel of charcoal—stir the charcoal every hour for two days—stirring so often may not be necessary—then draw off whiskey and put it in a still—distill it and it will be found perfectly clear of the apple—In this state if mixed with French brandy, jamaica spirit or holland gin in the proportion of about one third whiskey to 2/3 of foreign liquors it will impart to the liquor any unusual taste or flavor.
If in the distillation you add 15 or 20 lbs of juniper berries to the hogshead, it will make good gin.
Before the still is filled 15 or 20 gallons of Water must be put in the still.
A 60 gallon still may be run out twice in the day—Charcoal must be made out of maple, chestnut or light wood—must never be wet—When taken out of the coal pit they should be put out by throwing dirt over it—burnt perfectly well—out at the top so as to let the smoke out—to be ground fine.
The manuscript goes on to calculate that the profit on 100 gallons of apple whiskey converted to gin is $16.30, or about $225 in today’s money. Not enormous profit, but if it were steady, one eventually could buy a house.
Me? I think it would be a shame to strip the apples from apple brandy, especially when so many good ones are coming back on the market. If you're curious about American non-grape brandies and happen to be in New Orleans next month, check out Paul Clarke's session Fruit of the Still at Tales of the Cocktail.