Franklin and Bowdoin corresponded for forty years, often discussing their mutual scientific interests. In his letter, Franklin suggested he stop at Bowdoin's door the following morning, and mentioned scientific works that he would have delivered to Bowdoin. Referring to the enclosed recipe, Franklin wrote, "Herewith you have the Receipt you desired."

Franklin's Milk Punch recipe shares characteristics of two types of beverages--possets and syllabubs. Possets combine hot milk with ale, wine, or brandy, sugar, and spices. Heat and alcohol curdle the milk. Possets were used as remedies for colds, and were consumed from the spout of a posset cup, which let one drink the whey from the bottom and eat the curd later. Syllabubs combine milk with wine and lemon juice (or other acids); the acid from the wine and juice curdle the milk. Served in a glass, the foamy curd of the syllabub is eaten with a spoon and the punch drunk.

Modern adaptation of the recipe

For the adventurous, the following is a modern interpretation of Franklin's recipe, with portions reduced to one quarter of those suggested by Franklin. The flavor is lemony, with a slightly medicinal kick.

Ingredients:

6 cups (3 pints) of brandy
11 lemons
2 cups lemon juice
4 cups (1 quart) of spring water
1 freshly grated nutmeg
1 1/8 cups (1/2 lb) of sugar
3 cups of whole milk

Directions:

Zest eleven lemons.
Squeeze 2 cups of lemon juice.
Steep the lemon zest in the brandy for 24 hours.
Strain out the lemon zest.
Add 4 cups of spring water, 1 freshly grated nutmeg, 2 cups of lemon juice, and 1 1/8 cups of sugar to the brandy.
Stir until the sugar dissolves.
Bring 3 cups of whole milk to a boil.
As soon as the milk boils, add it hot to the brandy mix and stir.
The heat, lemon juice, and alcohol will begin to curdle the milk.
Let the punch stand for 2 hours.
Strain the punch through a jelly bag (or pillow case) until clear. Serve cold.