Hydrochloric acid 1.4 mol/l is mainly used in histology and pathology. In particular, it is used in the preparation of kerosene sections to remove calcium ions from tissue samples in order to achieve optimum section quality. The way it works is based on a chemical reaction: the HCl molecules in the solution react with the calcium ions in the tissue to form insoluble calcium chloride, which is washed out. The suitability of this solution is highly dependent on the concentration and pH, as differences in these parameters can affect the rate of reaction. In histology and pathology, hydrochloric acid 1.4 mol/l has become the preferred agent for decalcification of tissue specimens due to its specific properties.