Ascorbic acid is a sugar acid. It is white to light-yellow in colour, and comes in the form of crystals or powder. It is water-soluble. Ascorbic acid is one form of vitamin C, and was historically the first chemical compound to be synthesized, and identified, as vitamin C. The name is derived from a- (meaning "no") and scorbutus (scurvy), the disease caused by a deficiency of vitamin C.