The most dangerous cyanides are hydrogen cyanide -LRB- HCN -RRB- and salts derived from it , such as potassium cyanide -LRB- KCN -RRB- and sodium cyanide -LRB- NaCN -RRB- , among others .

The poisons referred to are usually hydrogen cyanide -LRB- HCN -RRB- , and the chemicals which are similar to it , like potassium cyanide -LRB- KCN -RRB- , and sodium cyanide -LRB- NaCN -RRB- .
