"'Portable Soup', also known as glue, was usually made from veal -- sometimes beef -- stock, reduced into a jelly that could be dried and stored. It was practical and, like the modern stock cube, would keep for years, easily reconstituted into a broth with the addition of hot water: ideal for both ships' captains and for cooks. Like the vilified French cullis, glue required quantities of meat -- Ann Blencowe used a whole leg of veal to make a piece no bigger than her hand, and Glasse's recipe called for 50 pounds of beef to 9 gallons of water. It also took hours to prepare, but at a time where fresh stock could sour in the space of a hot summer's afternoon, it could be a saviour."
--Kate Colquhoun, Taste: The Story of Britain Through Its Cooking (NY: Bloomsbury, 2007), 209