The Isinglass of Commerce. 239 



swells, and if held up to the light in this state is opalescent. 

 In boiling water pure isinglass is entirely dissolved, with 

 the exception of a very minute proportion of impurities. 

 Though the best isinglass is thus completely dissolved in 

 hot water, yet most of that met with in commerce does not 

 become so, in consequence of the presence of albuminous 

 parts. 



The fine shreds into which it is cut and kept in shops 

 give great facility for making a jelly in the shortest 

 possible time. This can be made palatable and nourishing 

 by the addition of sugar and milk, acids or spices ; about 

 one-third or half an ounce is sufficient for a. pint of water. 

 It may also be taken in the form of a soup, with the 

 addition of salt, spices, and sweet herbs, or it may be 

 employed medicinally as a demulcent, either externally or 

 internally. The best kinds of isinglass are alone employed 

 in articles of diet and for the best confectionery, being 

 added in small quantities to other, especially vegetable, 

 jellies, to give them a tremulous appearance ; but gelatine 

 is now frequently substituted. 



Isinglass appears to have been discovered many ages 

 since, for certainly it was known to the Romans, being 

 mentioned by Pliny. It is obtained in several parts of the 

 world from the air-vessels (termed " sounds " or " maws ") 

 of various species of sea, estuary, and fresh-water fishes, 

 England procures the best from Russia, where it is prin- 

 cipally collected from the family Accipenseridoe or stur- 

 geons, and the following species, according to Brandt 

 and Ratzeburg, furnish it : Accipenser sturio, the common 

 sturgeon ; A. huso, the great sturgeon ; A. Guldenstadtii, 

 the osseter; A. rathenus, the sterlet; A. stellatus, the 

 sevruga or starred sturgeon, in which account are likewise 

 included the A. brevirostris ; A. schypa ; A. Ratzcburgii ; 



