After looking into it, I learned that the calotype was invented by William Henry Fox Talbot and was a technical breakthrough that helped stimulate the world-wide spread of photography. Here he is (right) in his own calotype taking part in the purported oldest known photo of men drinking beer.
One of the men is the son of a Scotland brewer and they are drinking Edinburgh Ale. According to a contemporary account, Edinburgh ale was "a potent fluid, which almost glued the lips of the drinker together, and of which few, therefore, could dispatch more than a bottle.
Read more about the photo here and if you like, download the fullsized image in the link below.