Baker's Pure Rye 1847
Bottling Year & Age

1859 is the best candidate for when this was bottled, making it an 11 or 12 year old whiskey. Here's why.

W.T. Walters & Co. advertised the Bakers brand for decades. The graphics rarely changed, but the text did. And within all those ads, we find this one from 1859:

DeBow's Review, 1859, with typical barrel graphic of W.T. Walters & Co. but text includes a mention of 1847 when listing whiskeys in stock
  
"1847" is listed within their “largest stock of Old Rye Whiskey in the United States.” It's not right after “Baker,” but in no ads I've ever found did any date come in that spot. Baker is always listed first, with the same brands next, and vintages later.

I also can't find “1847" repeated in any ads before or after 1859.
 
There's always just been something appealing about "a dozen." 12 years was a premium age for whiskeys for the next century to come (e.g. Stitzel-Weller distillery's Very Very Old Fitzgerald of the 1960s).

Except for a hitch, which is that this is from DeBow's Review as published January 1859. The start of the year. Since the ad had to be given to the publishers earlier, that could mean three things: 1) Walters did so having already bottled the whiskey, 2) He anticipated selling this whiskey in 1859 and bottled it then, or 3) it could've been bottled "on demand" for consumers from the barrel. All those possibilities mean it's 11 or 12 years old by current standards.

Winnowing down other possibilities:

10 year old?  It's a nice round number, which would mean bottling in 1857. Except no ads from that year mention "1847." But they do list other years.

7, 8, 9 year old?  I have seen a vintage-dated 9-year-old Baker's bottled in the 1870s. But if this is an 8 or 9 year whiskey (bottled 1855/1856), I can't find ads from those years to support it, although that doesn't mean it's not possible. (1854 I can't find any ads from, anyone is free to help out!)

5, 6 year old?  Remember the whole premium, it-was-sold-in-a-bottle factor? That seems impractical for something younger and more common (whiskeys this age weren't unusual). Although, an 1852/5y bottling may make sense, since that was the year that Walters opened his landmark building at 68 Exchange Place, so it could've been some kind of celebratory thing.

2, 3, 4 year old?  Edwin would later recount that the company began sourcing for the brand in 1851, so presuming he was correct, these ages are not possible. 

13+ year old?
  Bottling in 1860 would make this a 13-year-old product, and there's a decent chance that consumers and merchants would've avoided that "unlucky" number. As for 1861+, that's when the Civil War broke out. Given the general chaos and the horrific spike in whiskey prices, it seems unlikely this already-expensive product would've been sold then, or thereafeter.
 
So we can't know with certainty, but it’s not unreasonable to think the 1859 advertisement above referred to this exact whiskey.
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