The Chemistry of Cookery

describes all the pretty gelatine preparations of the table as ‘calf’s-foot jelly,’ is founded on the greater solubility of the juvenile hoof, as compared to that of the adult ox or horse, or to the parings of hides about to be used by the tanner. All these produce gelatin by boiling, the calves’ feet with comparatively little boiling. Besides these differences there are decided varieties, or, I might say, species of gelatin, having slight differences of chemical composition and chemical relations. There is _Chondrin_, or cartilage gelatin, which is obtained by boiling the cartilages of the ribs, larynx, or joints for eighteen or twenty hours in water. Then there is _Fibroin_, obtained by boiling spiders’ webs and the silk of silkworms or other caterpillars. These exist as a liquid inside the animal, which solidifies on exposure. The fibres of sponge contain this modification of gelatin. Another kind is _Chitin_, which constituted the animal food of St. John the Baptist, when he fed upon locusts and wild honey. It is the basis of the bodily structure of insects; of the spiral tubes which permeate them throughout, and are so wonderfully displayed when we examine insect anatomy by aid of the microscope; also of their intestinal canal, their external skeleton, scales, hairs, &c. It similarly forms the true skeleton and bodily framework of crabs, lobsters, shrimps, and other crustacea, bearing the same relation to their shells, muscles, &c., that ordinary gelatin does to the bones and softer tissues of the vertebrata; it is ‘the bone of their bones, and the flesh of their flesh.’ It is obtainable by boiling these creatures down, but is more difficult of solution than the ordinary gelatin of beef, mutton, fish, and poultry. To this difficulty of solution in the stomach, the nightmare that follows lobster suppers is probably attributable. I once had an experience of the edibility of the shells of a crustacean. When travelling, I always continue the pursuit of knowledge in restaurants by ordering anything that appears on the bill of fare that I have never heard of before, or cannot translate or pronounce.