"Cavendish procured Macquer's neutral salt using Macquer's method of distilling with nitre, producing copious red fumes... leaving... a cake of neutral arsenical salt. He then tried... dissolving arsenic in spirit of nitre, then adding pearl ashes... to obtain neutral arsenical salt. ...[His] discovery: what combined with the alkali ...was ...a new acid, "arsenical acid" ...[T]his new acid had "all the properties of an acid... unless perhaps it should fail in respect of taste which I have thought not proper to try." This research was the high point of Cavendish's researches on ."