In the days before antibiotics, physicians used mercury bichloride (also called mercury chloride without the “bi”) to treat a variety of diseases, notably syphillis. Highly toxic, odorless, and colorless, it was meant to be applied topically to the sores that developed as this disease progressed. It was also used in very diluted form (1 part to 1000) for tonsillitis.
Several deaths during the Roaring Twenties brought this poison to the attention of the entire country. The first was the death in Paris of silent film star Olive Thomas, wife of leading man Jack Pickford whose sister, Mary Pickford, was the foremost actress of her day. Whether Olive’s death was accidental, as Jack always claimed, suicide, or murder was never determined. The French were quick to ship the body, Jack, and the scandal home to America where the controversy raged for months. No definitive cause of death was ever established. To read more, check wikipedia or http://www.silentsaregolden.com/articles/lpolivethomasdeath.html
Another highly publicized death occurred in 1925 when a young woman named Madge Oberholtzer was kidnapped, tortured, and raped by the head of Indiana’s powerful Ku Klux Klan. She managed to get hold of some mercury bichloride pills and swallowed them. She died a few days later after having had the presence of mind to accuse the Grand Dragon in signed testimony. Her written words were instrumental in convicting the man of murder, and the resulting publicity destroyed the KKK in Indiana. Details at wikipedia or http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=8390
Mercury bichloride was available at drug stores, sometimes by prescription only, sometimes not. Depending upon the state, a person who purchased poison of any sort was supposed to sign a register so there would be a record of the transaction. (We still have to do that for some drugs today.)
I use mercury bichloride and the poison registries in my second novel (yet to be published). If anyone has access to drug store “poison books” from the 1920s, I’d sure like to see a genuine example!