Police are still trying to find out who sent a parcel of potassium cyanide to the Osaka prefectural government in 1992.

ECONOMIST: The crazies and their poison

Stuart Lee, from Pillowell, admitted having hydrochloric acid, potassium cyanide and sulphuric acid which he stole from a business in Whitecroft.

BBC: Forest of Dean man guilty of explosives charge

The problem with chloroform, as with potassium cyanide and carbon tetrachloride, is that these poisons freeze the butterfly's muscles into an extreme version of rigor mortis, and the wings cannot be spread.

NPR: Excerpt: 'At Large and At Small'

During the fifties, when my brother and I started chasing butterflies, potassium cyanide was still in use as well, but because it is a deadly poison, Professor Klots recommended liquid carbon tetrachloride, which is "not very poisonous unless inhaled deeply, " and which we persuaded our parents was as innocuous as smelling salts.

NPR: Excerpt: 'At Large and At Small'