Mercury pigments and acid hematin are water soluble.

• A. True
• B. False
• C. Not stated
• D. Both are water soluble

Answer: (B)

Think about solubility: pigments are typically solids that stay dispersed, not dissolved, while certain stain formulations rely on dissolving a compound to create a solution that can diffuse into tissue.

Mercury pigments, such as cinnabar (mercury sulfide) and other inorganic mercury pigments, are insoluble solids. They do not dissolve in water and therefore are not water soluble. Acid hematin, on the other hand, is a form of hematoxylin that has been prepared in an acidic medium to produce a soluble staining solution; the hematoxylin component is dissolved in the acid, making it water soluble for staining. Because one component is insoluble and the other is soluble, the statement that both are water soluble is not correct.