I thought some people would from historical interest be interested in Byrn's (author of Complete Practical Distiller, a circa-1870 book published in Philadelphia, PA) other expedients to emulate the color of whiskey aged in wood barrels. He states you can use a "pint of parched wheat" and add that to a "barrel of whiskey", which he says gives a good color and improves the flavor.
If you have some Wheaties around, give them 30 minutes in the oven and add to a bottle of Georgia Moon, maybe it will taste like fine aged bourbon.
Second, he suggests adding oak bark shavings. I know some winemakers add oak chips to wines to impart an oaky or toasted taste, so this idea seems somewhat more "conventional".
Byrn has all kinds of ideas, e.g., contrary to the thinking today, he considers that liquor improves when stored in impermeable containers (whether glass or barrels specially sealed for the purpose). He advises to seal up barrels from the outside with an oil-based coating and then with pitch. He seems mainly concerned to avoid the economic cost of outage rather than to improve quality although he states clearly that spirits improve in containers impermeable to air, which seems rather startling today. Perhaps not everyone was convinced that long barrel aging was a good thing even some 40 years or so after it became the norm for fine bourbon and other quality spirits.
Byrn seems to contradict himself in that in another part of the book he advises to use temperature cycling for spirits in barrel to emulate long barrel aging. In his example, the spirits are kept in the artificially heated room for only a few weeks. He claims this can equal aging for a year or more. He states though that outage is the same either way.
I have the sense of someone who was a busy man in professional life and who only turned to the book when he had a few spare moments, so sometimes it seems repetitive or contradictory.
Still, it is a valuable resource to try to understand what whiskey was like in the mid-19th ecntury. He never uses the term bourbon for example although he does refer to whiskey made from "Indian corn". It seems at the time that the benefits of aging (as the discussion above shows) were understood but that whiskey, when it was aged, would not have undergone more than a year or so of storage and often was sold new, hence the many rectification techniques he describes. These include multiple distillation, dosing with fruity additives, charcoal and wool blanket filtrations of various types, chemical treatments of various kinds and simple "dulcification" (adding sugar).
There must have been numerous books of this kind written at the time sitting in libraries still and if one could read them all I am sure it would give a better picture of what bourbon and rye were like in the mid-1800's.