From London's Ghost Acres
Isinglass is a substance obtained from the dried swim bladders of fish. It is a form of collagen used mainly for the clarification or fining of beer. It can also be cooked into a paste for specialized gluing purposes.
Isinglass is included in the Compendium under the “Cookery for the Sick” section, and is included in a recipe for Coffee Milk (isinglass is used to clarify the mixture), and in the recipe for An Excellent Jelly.
British Pharmacopoeia 1867
“The swimming bladder or sound of various species of Acipenser… prepared and cut into fine shreds.”  (381)
A Compendium of Domestic Medicine, 1865 Isinglass
Cookery for the Sick that includes
- An Excellent Jelly (Another): boiled shavings of isinglass, with Jamaica Peppers, and a brown crust of bread. Makes a jelly that can be “taken in wine and water, milk, tea, or soup.”
- Coffee Milk: shaved isinglass added to ground coffee that has be boiled in milk. Used to clarify the mixture.
- British Guiana
- British India
- Singapore and Eastern Straits Settlements
- German East Africa
<ref> tags exist, but no
<references/> tag was found