Gram's Crystal Violet is used for Gram's staining. In practice, a smear of bacterial cells is stained with crystal violet, then treated with an iodine containing mordant to increase the binding of primary stain. A decolourizing solution is used to remove the crystal violet from cells which bind it weakly and then the counterstain with safranin.

Negative staining method permits visualization of the usually transparent and unstainable capsule of many organisms, most importantly Cryptococcus neoformans. Nigrosin consists of a suspension of fine particles of carbon. These form a dark background.

Fixative is recommended to fix cytological and histological samples specially vaginal smear (for PAP staining). It preserve cellular morphology of specimen sample

Urea Indole Medium is recommended for differentiation of micro-organisms especially Enterobacteriaceae on the basis of their ability to hydrolyze urea and indole production. This medium is very useful in the identification of Proteus species from Salmonella and Shigella species. L- Trypytophan is an essential amino acid and is converted to skatole and indole, which is detected by the addition of Kovacs Reagent (R008). Sodium chloride maintains the osmotic balance. The phosphates helps in the buffering of the medium. Microorganisms that possess the enzyme urease hydrolyse urea , releasing ammonia, which is detected by the pH indicator phenol red . The alkalinility so developed imparts pink colour to the medium. Proteus species show positive urease reaction.

For the cultural isolation of Neisseria and Haemophilus species from a variety of clinical specimens.