KÜHNE carbolic methylene blue is a specialized laboratory chemical essential for microscopic studies in biology and medicine. This solution, composed of methylene blue, phenol, ethanol and water, is known for its unique staining properties. Methylene blue, a heterocyclic aromatic chemical compound with the formula C16H18N3SCl, acts as an intense blue colorant. Phenol serves as a mild disinfectant and can denature proteins and lipids in biological samples, which improves the staining characteristics of methylene blue. The ethanol component aids the penetration of the dyes into biological tissues. In application, this solution can be used to stain cells and tissues for microscopic observation, making specific structures or organisms, such as bacteria and fungi, more visible. KÜHNE carbolic methylene blue thus helps optimize laboratory efficiency in microscopic studies.