This sputum flask was used to help prevent the spread of disease especially by tuberculosis patients, through people spitting in public. They became know as a Blue Henry. They are made of Cobalt Glass, hence blue.These flasks were in wide use opera a period of about 50 years, and manufactured by many different manufacturersBlue Glass labelled Mignon. Large metal cap one end with spout inside glass beneath cap. Small metal cap at other end. Oval in shape."Mignon" both on large metal cap and on glasscobalt blue sputum flasks