False colour scanning electron micrograph of crystals of potassium hydrogen tartrate, also known as cream of tartar. These crystals precipitated out from a commercial red wine & were found on the inner surface of the cork. Grapes are unusual in that they produce large quantities of tartaric acid, together with some malic acid, whereas most fruits contain citric & malic acid. Magnification: X 40 at 6x7cmsize. Original is bw print a600/290.