Used in Alizarin Red S and Toluidine Blue O for distinction of bone and cartilage in mammalian embryos. See Dawson A.B., Stain Techn., 1:123-4, 1926, Williams, T.W., Stain Techn., 16:23-5, 1941, or Clark, G., (ed), Staining Procedures, 3rd Ed., Williams & Wilkins Baltimore, p. 139, c. 1973