Noah Webster
Quintessence
QUINTES'SENCE, noun [Latin quinta essentia, fifth essence.]
1. In alchimy, the fifth or last and highest essence of power in a natural body. Hence,
2. An extract from any thing, containing its virtues or most essential part in a small quantity.
Let there be light, said God; and forthwith light etherial, first of things, quintessence pure, sprung from the deep.
3. In chimistry, a preparation consisting of the essential oil of a vegetable substance, mixed and incorporated with spirit of wine.
4. The pure essential part of a thing.
[I have followed Bailey and Ash and our general usage in the accentuation of this word. Jameson has done the same. The accent on the first syllable is very unnatural.]