From London's Ghost Acres
Gum Benzoin / Benzoin Commonly used in incense-making and perfumery, due to its sweet-vanilla smell and fixative properties (allowing for slower dispersal of essential oils and other mineral fragrances). It can also be used in cosmetics, veterinary medicines, and candles. As a flavourer it is found in alcoholic and non-alcoholic beverages, baked goods, chewing gum, frozen dairy, gelatins, puddings, and soft candies.
There are two types of Benzoin: benzoin Siam (Styrax tonkinensis found in Thailand, Laos, Cambodia, and Vietnam), and benzoin Sumatra (Styrax benzoin, found on the island of Sumatra).
The only medical entry for Benzoin in either the Pharmacopeia or the Compendium is in the Compendium, and is used in the treatment of cough.
British Pharmacopoeia 1867
Used to make Benzoic acid, have not included entries under Benzoic acid in this section
“a balsamic resin obtained from Styrax Benzoin… It is procured by making incisions into the bark of the tree, and allowing the liquid that exudes to concrete by exposure to the air. Imported from Siam and Sumatra.” 
“In lumps, consisting of agglutinated tears, or of a brownish mottled mass with or without white ters imbedded in it; has little taste, but an agreeable odour; given off, when heated, fumed of benzoic acid; is soluble in rectified spirit and in solution of potash.” Used in preparations of:
- Acidum Benzoicum
- Adeps Benzoatus
- Tinctura Benzoini composita
Preparations of Benzoin
Benzoic Acid / Acidum Benzoicum
- “a crystalline acid obtained from benzoin, and prepared by sublimation… In light feathery crystalline plates and needles, which are flexible, nearly colourless, and have an agreeable aromatic odour, resembling that of benzoin.”
- dose: 10-15 grains
- used in preparations of: Ammoniae Benzoas, Tinctura Camphorae composita, Tinctura Opii Ammoniata
Benzoated Lard / Adeps Benzoatus
- Prepared Lard (1 pound), Benzoin, reduced to coarse powder (160 grains)
- used in the preparations of: Suppositoria Acidi Tannici, Suppositoria Hydrargyri, Suppositoria Morphiae, Suppositoria Plumbi composite, Unguentum Gallae, Unguentum Plumbi Acetatis, Unguentum Sulphuris, Unguentum Zinci
Tincture of Benzoin / Tinctura Benzoini composita 
- benzoin, in coarse powder (2 oz), prepared storax (1 ½ oz), balsam of tolu (1/2 oz), socotrine aloes (160 grains), rectified spirit (1 pint)
- dose: ½-1 fl drachm
A Compendium of Domestic Medicine, 1865
Diseases Treated with
- Cough: benzoin can be used to treat a habitual cough, common in old age.
- Cough Pill: flowers of benzoin (this could be benzoic acid, which is usually derived from gum benzoin)
- General Medical Council of Great Britain, British Pharmacopeia, (London: Spottiswoode & Co.,1867), 55 https://archive.org/details/britishpharmacop00gene
- GMCGB, 55-56
- GMCGB, 7
- GMCGB, 26
- GMCGB, 321
- Savory, John. A Compendium of Domestic Medicine (London: John Churchill and Sons, 1865), 218. https://books.google.ca/books?id=VxoDAAAAQAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
- Savory, 324