Water blue
（重定向自Aniline blue）
![](/Images/godic/202412/21/Water_blue23322.png")
Water blue, also known as aniline blue, Acid blue 22, Soluble Blue 3M, Marine Blue V, or C.I. 42755, is a chemical compound used as a stain in histology. Water blue stains collagen blue in tissue sections. It is soluble in water and slightly soluble in ethanol.