Summary

1911 Encyclopædia Britannica, Volume 14… (1911)

The finest isinglass, which comes from the Russian ports of Astrakhan and Taganrog, is prepared by steeping the sounds in hot water in order to remove mucus, &c.; they are then cut open and the inner membrane exposed to the air; after drying, the outer membrane is removed by rubbing and beating. As imported, isinglass is usually too tough and hard to be directly used.
Source: Wikisource

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