What does Prussian blue and Bluing have in common?
Bluing (fabric) Bluing, laundry blue, dolly blue or washing blue is a household product used to improve the appearance of textiles, especially white fabrics. Used during laundering, it adds a trace of blue dye (often synthetic ultramarine, sometimes Prussian blue) to the fabric.
Blue Cross (chemical warfare) Blue Cross (Blaukreuz) is a World War I chemical warfare agent consisting of diphenylchloroarsine (DA, Clark I), diphenylcyanoarsine (CDA, Clark II), ethyldichloroarsine (Dick), and/or methyldichloroarsine (Methyldick). Clark I and Clark II were the main agents used.