4-08 
Isinglass. 
perfectly unfolded. By this simple operation we find 
that isinglass is nothing more than certain membranous 
parts of fishes divested of their native mucosity, rolled 
and twisted into the forms above mentioned and dried in 
ijie open air. 
The sounds or air bladders of fresh water fish in gene» 
ral are preferred for this purpose, as being the most trans- 
parent, flexible, delicate substances. These constitute 
the finest sorts of isinglass ; those called book and ordinary 
staple are made of the intestines, and probably of the peri- 
toiiceum of the fish. The belluga yields the greatest 
quantity, as being the largest and most plentiful fish in 
the Muscovv rivers ; but the sounds of all fresh- water 
fish yield more or less fine isinglass, particular!}^ the small- 
er sorts, found in prodigious quantities in the Caspian 
sea, and several hundred miles beyond Astracan, in the 
Wolga, Yaik, Don, and even as far as Siberia, where it 
is called kla by the natives, which signifies a glutinous 
matter ; it is the basis of the Russian glue, which is pre- 
ferred to all other kinds for its strength. The sounds, 
which yield the finer isinglass, consist of parallel fibres^, 
and are easily rent longitudinally, but the ordinary sorts 
are found composed of double membranes, whose fibres 
cross each other obliquely, resembling the coats of a blad- 
der ; hence the former are more readily pervaded and di- 
vided with subacid liquors, but the latter, through a pe- 
culiar kind of interwoven texture, are with great difficul- 
ty torn asunder, and long resist the pov/er of the same 
menstruum ; yet when duly resolved are found to act 
with equal energy in clarifying liquors. 
Isinglass receives its diflerent shapes in the following 
manner : 
The part of which it is composed, particularly the 
sounds, are taken from the fish while sweet and fresh, slit 
©pen, washed from their slimy sordes^ divested of 
