Use "plumbago" in a sentence

1. It is said that the essential oils of plumbago help to improve the glandular swelling,

2. It gives the usual greenish trace on white pottery, while a line drawn parallel on the same basis, by a piece of plumbago or black-lead, is black; this being (as pointed out by Brongniart) the easiest criterion, by which to distinguish between molybdena and plumbago, or black-lead

3. —In Cornwall, Litchfield county, Connecticut, plumbago is found, of a good quality, and in considerable masses, in a vein contained in a rock of gneiss, or mica-slate