Disinfectant fluids are homogeneous solutions of coal tar acids or similar acids derived from petroleum that contain phenolic compounds. They are black in color and become translucent off-white when diluted with water. The fluids contain monochlorophenol or chloroxylenol, and a higher Rideal Walker constant value of these compounds indicates better quality. The document provides links to additional information on related topics like white phenyl, black phenyl, and contact information for the company.