Ashtangasamgraha 32.12

32.12

One should prepare a sweet [collyrium] in a gold vessel;
a sour one in silver;
a salty one in [a horn of] a ram's horn;
a bitter one in bronze;
a pungent one in a lapis lazuli or stone vessel;
an astringent one in a copper or iron vessel;
and a cold one in any of reed, plakṣa, lotus, crystal, conch shell, and the like.
In this way, its qualities do not deteriorate.
And the stone for grinding the wick should be very smooth, depressed in the center, not flaking, five fingers long, and three fingers wide.