As it stands now, I have found references for a "Franklin Bottling" located in Philadelphia between 1906 and 1943. If this information is accurate, I'm guessing your "Franklin's Flip" bottle was produced no later than 1943. ???
Hot Ale Flips were all the rage at a time when fire pokers were ubiquitous hearth accouterments and warm beer was lauded as tonic. One of the earliest known mixed drinks, the flip was referenced as early as 1695 in William Congreve’s society farce Love for Love: “We’re merry folks, we sailors: we han’t much to care for. Thus we live at sea; eat biscuit, and drink flip.”And though flips were associated with a rough crowd in England (Nathan Bailey’s An Universal Etymological English Dictionary  defines flip as “a sort of Sailor’s Drink”), it was beloved in taverns on the other side of the Atlantic. George Washington was known to drink them in the early years of America.
In those days, ale was often mulled (finding an ice-cold one would’ve been something of a challenge—refrigeration wasn’t invented yet), and doctors prescribed it for indigestion, insomnia and colds. In taverns, flips were often composed of rum or brandy, eggs, molasses or sugar and beer all mixed together in a pitcher and then stirred to a caramelized froth with a hot poker. The poker was eventually replaced with the “ale-warmer,” which consisted of a tin or copper vessel that heated and funneled the drink from the pitcher to the pint. Today, the stove top will do just fine.
Ale Flip: A Colonial Cocktail Recipe
Prep time: 10 minutes
Total time: 10 minutes
Makes 1 drink Special Equipment:
Boston shaker or 2 pint glasses
1 1/2 fl. oz. (3 tablespoons) rum
1 tablespoon molasses
1 large egg
8 fl. oz. (1 cup) dark beer such as brown ale, porter, or stout
freshly grated nutmeg for garnish
Pour the rum and molasses into one of the pint/shaker glasses. Crack the egg into the other glass and beat well with a fork.
Warm the beer in a small saucepan over low heat just until it begins to froth and steam; don’t let it come to a boil.
Pour the beer into the glass filled with rum, then pour the egg into the beer. Continue to pour the drink back and forth between the pint glasses until smooth and well-blended, then transfer to a mug or other clean and heat-safe drinking glass.
Grate fresh nutmeg over the flip and serve immediately.
That reminds me of a party I was at once where they tried making something from a 16th century recipe called buttered beer. It basically involved putting eggs, butter, sugar, and spices into beer. I'm not sure if they made it wrong or not, but the egg cooked and turned solid and the butter floated around on top. I was not brave enough to try the final product.
Rum, molasses, and egg in a beer? Wow.
The base by the way is <0I> with a date code of "6" and it's Duraglas. What's that make it... 1956? '46?
Duraglas (a glass hardening agent) was introduced in 1940 - plus a solo 6. would indicate your bottle was made in 1946. By 1956 Owens Illinois was using double-digit dates such as ... 9 <(I)> 56
If the beverage itself was intended to replicate a Colonial flip, I can only imagine what it taste like - but thinking it might have been some type of root beer. The possibility that your bottle might be the only known example suggest that it might have had a short run for some reason - possibly because it didn't sell well. And if it taste like I think it might have, its no wonder.
there is no harm in looking , never know what you might find . the storms and hurricanes might of actually unearthed or moved things which had been hidden for some time . often things are found after...