Modifies a noun

• poisoning: During World War I the house was occupied by Harold Greenwood, a solicitor accused of killing his wife by arsenical poisoning.

• copper: Whatever the truth of central Europe's arsenical copper in the 4th millenium, Britain remained literally in the Stone Age.

• pyrite: The lode is a large irregular one of pure arsenical pyrites carrying, in addition to gold and silver, nickel and cobalt.

• brass: For special purposes where even better corrosion resistance is required, aluminum or arsenical brasses are available.