Isinglass

Isinglass flummery.—Put six ounces of isinglass into a quart of new milk, sweeten it, set it over the fire, and keep it stirring one way all the time, till it is jellied; pour it into basins, and when cold turn it out; you may put in orange flower water if you like.

Source: wiktionary

Isinglass is a substance well known in commerce, from its employment both in the arts and in domestic economy. It is the purest known form of animal jelly, and is obtained from the swimming bladder of a few kinds of fish, chiefly of the genus Sturgeon, the Acipenser of zoologists. This is indicated by some of its continental names, of which the English is no doubt a corruption;—thus, in German, Isinglass is called Hausenblase, from hausen the great sturgeon, and blase a bladder.

Source: wiktionary

Isinglass is brought to market in different forms, sometimes in that of simple plates, at other times rolled up in different shapes, or cut into fine thread. When of good quality isinglass is of a whitish colour, thin, and semi-transparent, but tough and flexible, destitute of taste as well as of smell. The inferior kinds are thicker, yellowish-coloured, opaque, and sometimes have a fishy smell and taste. In boiling water isinglass is entirely dissolved, with the exception of a very minute portion of impurities.

Source: wiktionary

Isinglass.—This is procured from the air-bag or swimming-bladder, sometimes termed the sound, of various fishes. […] Sometimes the bag is dried unopened, as in the case of the purse, pipe, and lump isinglasses of the shops. At other times it is laid open, and submitted to some preparation; being either dried unfolded, as in the leaf and honeycomb isinglasses; or folded, as in the staple (long and short) and book isinglasses; or rolled out, as in the ribbon isinglass.

Source: wiktionary