Cream of Tartar, actually made from dental scrappings. that nasty Tartar build-up.

cream of tartar "Potassium bitartrate also potassium hydrogen tartrate has formula KC4H5O6. It is a byproduct of winemaking. It is also known as cream of tartar. It is the potassium acid salt of tartaric acid." "Occurrence Potassium bitartrate crystallises in wine casks during the fermentation of grape juice. In wines bottled before they are fully ripe, argol can precipitate on the side of the bottle in a sort of crust, thus forming what is called "crusted wine". This crude form (known as beeswing) is collected and purified to produce the white, odorless, acidic powder used for many culinary and other household purposes. Applications - In food In food, potassium bitartrate is used for: Stabilizing egg whites, increasing their heat tolerance and volume; Preventing sugar syrups from crystallising; Reducing discolouration of boiled vegetables; Frequent combination with baking soda (which needs an acid ingredient to activate it) in formulations of baking powder. Commonly used in combination with potassium chloride in sodium-free salt substitutes A similar acid salt, sodium acid pyrophosphate, is confused with cream of tartar due to their similar function in baking powder." Source and further information: http://en.wikipedia.org/wiki/Cream_of_tartar