A catalytic process that was once used to convert hydrochloride gas to chlorine gas used in the manufacture of bleaching powder. The bleach was used in the textile and paper industries, and the process was able to reduce the production of hydrochloric acid as a waste product. It involved reacting hydrochloric acid and oxygen in the form of air at a temperature of between 400°C and 450°C in the presence of a copper chloride catalyst:

(p. 97) The process was invented by British chemist Henry Deacon (1822–76) as a way of using the hydrochloric acid from the Leblanc process. The process was later replaced by an electrolysis process for making chlorine from brine.