Used in histology and microbiology as a staining reagent, particularly in Gram staining to differentiate Gram-positive and Gram-negative bacteria. The solution helps in the visualization of bacterial cell walls under the microscope by selectively retaining the crystal violet dye in Gram-positive organisms. Ammonium oxalate acts as a mordant, enhancing the binding of the dye to cellular components. It is also employed in some fungal staining protocols and in the preparation of slide cultures for microscopic examination. Commonly used in clinical labs and research settings for rapid bacterial identification.