This is a reference to gelatine, a translucent, flavourless substance derived from animals’ skin and bones. Collagen – a tissue in the connective joints of animals – is extracted by boiling bones and hide, forming a colourless gel which is brittle when dried. Gelatine is sold in powder, granules or sheets and is used as a gelling agent in cosmetics, pharmaceuticals and cooking, creating foodstuffs such as gummy sweets, jams, yoghurts, trifles and jellies.
The most common source of gelatine in the nineteenth century was calves’ feet. Today it is the hide and bones that are used, usually those of cattle.
See a list of gelatine dessert recipes, including jellies, pies and chewy sweets.