Saccharin is the oldest artificial sweetener; it was discovered in 1879 by Ira Remsen and Constantin Fahlberg of Johns Hopkins University. In the European Union, it is also known under the E number (additive code) E954.
Saccharin is about 300 times as sweet as sucrose, but has an unpleasant bitter or metallic aftertaste, especially at high concentrations. Unlike the newer artificial sweetener aspartame, saccharin is stable when heated, even in the presence of acids, does not react chemically with other food ingredients, and stores well. Blends of saccharin with other sweeteners are often used to compensate for each sweetener's weaknesses. A 10:1 cyclamate:saccharin blend is common in countries where both these sweeteners are legal; in this blend, each sweetener masks the other's off-taste. Saccharin is often used together with aspartame in diet fountain beverages, so that some sweetness remains should the fountain syrup be stored beyond aspartame's relatively short shelf life.
In its acidic form, saccharin is not particularly water-soluble. The form used as an artificial sweetener is usually its sodium salt. The calcium salt is also sometimes used, especially by people restricting their dietary sodium intake. Both salts are highly water-soluble: 0.67 grams per milliliter water at room temperature.