Blue mass was recommended as a remedy for such widely varied complaints as tuberculosis, constipation, toothache, parasitic infestations, and the pains of childbirth. It was a magisterial preparation, compounded by pharmacists themselves based on their own recipes or on one of several widespread recipes. It was sold in the form of blue or gray pills, or syrup. Its name probably derives from the use of blue dye or blue chalk (used as a buffer) in some formulations.

The ingredients of blue mass varied, as each pharmacist prepared it himself, but they all included mercury in elemental or compound form (often as mercury chloride, also known as calomel). One recipe of the period included (for blue mass syrup):

    33 parts mercury
    5 parts licorice
    25 parts Althaea (possibly hollyhock or marshmallow)
    3 parts glycerol
    34 parts rose honey

Blue mass was also used to treat syphilis, in the form of ointments, gargles, and eye washes. Obviously it also poisoned the patient.

-Adam Miller
Folksinging.org