i Register
In some senses, menstruum is marked as historical. Watch for register when choosing this word.
noun
The menses; menstrual discharge.
A solvent.
Whenever any menstruum or other additament is employed, together with the fire, to obtain a sulphur or a salt from a body, we may well take the freedom to examine, whether or no the menstruum do barely help to separate the principle obtained by it...
[T]hat combustible sulphureous Body is presently prey'd upon and devoured by the aereal incompassing Menstruum, whose office in this Particular I have shewn in the Explication of Charcole.
Any liquid medium