Hydrochloric acid in ethanol - for microscopy, is used for human-medical cell diagnosis and serves the purpose of the bacteriological and histological investigation of sample material of human origin. Acid-fast bacteria are difficult to stain because of the high proportion of lipid and wax in their cell walls. The most efficient staining method is the hot staining according to Ziehl-Neelsen. In this method, carbolfuchsin solution is applied to the specimen and heated. This heating process accelerates the rate at which the fuchsin dye is absorbed and thus also that of the formation of the mycolatefuchsin complex in the cell wall. With the Kinyoun method, a modification of the AFB-Color carbol fuchsin solution renders heating unnecessary (cold staining). Once the acid-fast bacteria have absorbed the fuchsin dye, it is virtually impossible to decolorize them again, even when they are intensively treated with a decolorizing solution such as e. g. hydrochloric acid in ethanol (Product number 1.00327). Accordingly, acid-fast bacteria are termed as acid- and alcohol-fast for staining, and are stained red in the microscopic visualization. Correspondingly, all non-acid-fast microorganisms are counterstained with an appropriate dye. In this instruction for use malachite green is used for counterstaining.