Ishmael explains ambergris a bit more: it’s a "soft, waxy... highly fragrant and spicy" substance that is "largely used in perfumery, in pastiles, precious candles, hair-powders, and pomatum" (92.1)
It’s found in the bodies of sick whales, although nobody’s sure if it’s the cause or the effect of the illness.
Ishmael develops a metaphor about finding this fragrant and precious substance in the decaying corpse of a sick animal—it’s like what St. Paul says about the soul being "sown in dishonor" and "raised in glory."
Ishmael concerns himself with making the point that whaling isn’t usually a gross, unclean business, the way the Rose-bud made it appear.
He claims that, if everything is done properly, whales’ corpses and their oil are "nearly scentless" (92.7) or at least just have a pleasant musk and perfume.