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.

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.

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.

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.

The sturgeon yielded a non-food product that was important for domestic and commercial use. This was isinglass, a gelatinous substance that was derived from the inner membrane of the air bladder (also called the swimbladder, or sound). Isinglass had a variety of uses. The Ojibway valued it as an effective binding agent in the manufacture of paint. Isinglass was also a product much in demand in Europe during the fur trade period. It was noted as producing a high quality glue and as a fining agent for beers and wines.

Not all fish have swim bladders, and those from certain tropical or semitropical areas (roughly 20° N and 15° S) provide the best quality isinglass for fining purposes. Of these fish, the threadfin family (Polynemoidia) provide excellent quality. In order to gain a desirable fining quality for a particular beer type, two or more kinds of isinglass may be blended. To illustrate this more precisely, Polynemus isinglass provides a fining that settles densely, whereas Silurus isinglass, from the great catfish family (Siluridae) in South America, gives a more flocculant fining but which settles less densely and consequently is more easily disturbed.

There is a general error prevalent that mica is isinglass, and many times it is spoken of as isinglass, but there is a great difference between the two. Mica is mainly composed of silicate of aluminum, while isinglass is a fish gelatine or glue […]

The dashboard's genuine leather, / With isinglass curtains y' can roll right down, / In case there's a change in the weather.