Note 449 — LETTER VIII.
Reading edition
It is not its hardness that protects the teak, as the Asiatic Termites attack Lignum Vitæ, but probably some essential oil disagreeable to them with which it is impregnated. This is the more likely, since they will eat it when it is old and has been long exposed to the air. Tannin has been conjectured to be the protecting substance, but erroneously, as leather of every kind is devoured by them. Williamson's East India Vade Mecum, ii. 56. It is its hardness probably that protects the iron-wood from the African Termites. Smeathman in Philos. Trans. 1781. 11. 47.