ACIPENSER HUSO. 



containing usually a mixture of oxygen and nitrogen in vari- 

 ous proportions. This has been denominated the swimming- 

 bladder, because by its expansion or contraction it is sup- 

 posed to enable the fish to rise or fall in the water. It is of 

 different shape in different fishes, and consists of three coats, 

 of which the two interior are thin and delicate, the outer 

 tough and of a silvery whiteness. 



The species of sturgeon from which THE BEST ISINGLASS 

 is procured is particularly the Acipenser huso of Russia ; but 

 others, as the Acipenser sturio, Acipenser ruthenus, &c. (already 

 noticed), furnish large quantities to commerce. Immense 

 quantities are annually caught and consumed as food. The 

 air-bags are removed from the fish, and, having been split 

 open and washed in water in order to separate the blood, fat, 

 and adhering extraneous membranes, are spread out, and 

 when sufficiently stiffened are formed into cylindrical rolls, the 

 ends of which are brought together and secured by pegs. The 

 shape given to the roll is that of a staple, or more accurately 

 that of a lyre, which it firmly retains when dried. Thus pre- 

 pared, it is known in commerce by the name of staple isinglass, 

 and is distinguished into the long and short staple. Some- 

 times the membranes are dried in a flat state, or simply 

 folded, and then receive the name of leaf or book isinglass. 

 The scraps or fragments of these varieties, with various other 

 parts of the fish, are boiled in water, which dissolves the gela- 

 tine, and upon evaporation leaves it in a solid state. This is 

 called cake isinglass, from the shape which it is made to 

 assume. It is sometimes, however, in globular masses. Of 

 these varieties the long staple is said to be the best, but the 

 finest book isinglass is not surpassed by any brought to mar- 

 ket. It is remarkable for its beautiful iridescence by trans- 

 mitted light. Cake isinglass is brownish, of an unpleasant 

 odor, and employed only in the arts. Inferior kinds, with the 

 same commercial titles, are sometimes prepared from the peri- 

 toneum and intestines of the fish. 



Isinglass little inferior to the Russian is made in Iceland 

 from the sounds of the cod and ling. Considerable quantities 

 of isinglass are manufactured in New England from the intes- 

 tines of the cod, and of some of its allied fishes. This sort is 

 in the form of thin ribbons, several feet in length, and from 

 an inch and a half to two inches in width. Isinglass of a 

 good quality has also been made in New York from the 



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