inheritance powder
nounEtymology So called because one person might murder another to gain an inheritance.
1
Historical Any of several poisons used for murder, but especially arsenic and, to a lesser extent, thallium.
- `Arsenic was very popular in the old days [...] Inheritance powder, they called it. Pure, deadly, white, dissolves in any weak acid.'2016, Kerry Greenwood, Murder and Mendelssohn, Sydney: Allen and Unwin, page 316: