Arsenical copper
Arsenical copper contains up to 0.5% arsenic which, at elevated temperatures, imparts higher tensile strength and a reduced tendency to scaling. It is typically specified in boiler work, especially locomotive fireboxes.{{Cite book |title= Metallurgy for Engineers |last= Rollason |first= EC |edition= 2nd |year= 1949 |publisher= Arnold |location= London }}{{cite web |url= http://dipp.gov.in/boilerrules_previous/reg129a.htm |title=IBR - 1950 : Reg. 129 A |access-date= 2010-01-21 |url-status= dead |archive-url= https://web.archive.org/web/20090319043815/http://dipp.gov.in/boilerrules_previous/reg129a.htm |archive-date= 2009-03-19}}{{Cite web |url= http://www.steamindex.com/jile/jile42.htm |title= Journmal Institution Locomotive Engineers Volume 42 (1952)}} It also helps prevent embrittlement of oxygen-free copper by bismuth, antimony and lead by the formation of complex oxides. Copper with a larger percentage of arsenic is called arsenical bronze, which can be work-hardened much harder than copper.