This is a sign that the bath is deficient in potassium cyanide.

All the men and their families were then issued with potassium cyanide.

Some cyanide formulasare famously deadly, notably hydrogen cyanide or potassium cyanide.

Might you not have used potassium cyanide or prussiate of potash?

According to his company, Hibi has easy access to potassium cyanide through his work.