Mystery solved! It is...
A balsam bottle for storing/applying microscope slide mounting media.… Canada Balsam is a natural mounting medium obtained from balsam fir trees for microscopy. The optical properties are nearly identical with those of glass. Specimens must be dehydrated. Permanent slides mounted with balsam have been stored for over a century. The glass tube applicator (which this is missing along with the cap) is held in place by a thin wire that winds around the inside of the metal cap. Neck of bottle and brown tinted glass insert are ground glass to promote a better seal. Bottom of bottle marked: T. C. W. Co. U.S.A. Main bottle contains approximately 35mL and upper insert contains approximately 9 mL to upper neck constriction. Gluing microscope specimens to slides! They say some of these balsam glued specimen slides have survived for over a century.
Thank you Chris and all who took a look...some of the modern day bottles for this purpose can sell for up to $500.
