Below I’ve appended pages from Harrison Hall’s 1818 The Distiller. Despite the letter to the Sun in 1908 that claimed it was printed at New York, the title page states Philadelphia. Hall seems to have been familiar with distilling in the northeast in general. I’m not sure where he was actually based but it appears to have been in Philadelphia. (There were two editions of this book, one from five years earlier, but both printed in Philadelphia as far as I know).
The “western” territories are clearly Kentucky and Tennessee, not Ohio. This western whiskey was made mostly from corn. It was also aged to some degree and improved by boat shipment. One can assume that a combination of inventory storage and subsequent boat shipment resulted in a product somewhat similar to modern two-year-old bourbon although whether new charred barrels were used, or always used, seems doubtful (too early).
Either way, this whiskey so liked in eastern markets was a proto-bourbon, clearly.
What was “fourth proof spirits”? The definitions varied according to state regulation. I have seen numbers between 100 U.S. proof (50% abv) and 120 (60% abv). This definition is helpful, from 1857, which pegs the proof number at 120 and also because it states fourth proof spirits are highwines. That ties in to the 1908 letter, and 120 proof is a typical range for whiskey-mash, 1800s or today.
However, even 90% highwines, let alone 94%, are not 60% highwines and the writer of the letter misses this, IMO. As I’ve shown, the highwines definition changed as stills improved over the 1800s. Hall admired double-distilled spirits – first run in a wash still, then doubling in the spirits still – because the foreshots were removed as were the feints. These are the impure fractions that correspond broadly to methanol and other low-boiling by-products and the higher alcohols generally called fusel oils, the high-boilers. But even white dog spirit of this type, or as results from a modern bourbon distillation in the column still, is very far from neutral in taste.
Once again everything is relative. Hall was contrasting double-distilled spirits, perhaps subsequently leached through charcoal, either with “singlings”, the first run from the pot still containing all the fractions of distillation, or double-distilled spirits tainted by addition of feints. But there is a reason white dog is called what it is…
Among various advances in distilling discussed by Hall in the volume, he mentions early steam distillation techniques. He also pumps up “neutralized” spirit, which he terms, in addition, “tasteless”. He states this is useful to blend with other distillates – gin, brandy – to form imitations. This was a frequent early-1800s practice, Canadian distillers did it too.
He states with rum there is so much oil in it such blending is actually helpful, it improves the product. Here we see an early glimmer of the blending rationale of the later-1800s.
A better analogy for 90%-94% abv highwines would be Hall’s neutralized spirits, not fourth proof whiskey. But how neutral was it? “Tasteless” seems pretty clear, mind you, and Hall had great trust in charcoal rectification. Yet, I’ve tasted Jack Daniel’s white dog after its run through the maple charcoal vat. Neutral it’s not.
It’s difficult to parse these sources over such a long period. Has any craft distiller, or any distiller, for that matter, built a 19th century charcoal leaching vat to see what it can do for white dog? Maybe Jack Daniel and George Dickel, the great Tennessee whiskey names, haven’t exhausted its possibilities.