Moby Dick Chapter 77 The Great Heidelburgh Tun
http://www.gutenberg.org/files/2701/270 ... m#2HCH0077
The Sperm Whale's head is a solid oblong, with the cranium and jaws surmounted by an unctuous mass wholly free from bones. The lower part, called the junk, is one immense honeycomb of oil. The upper part, known as the Case, may be regarded as the great Heidelburgh Tun of the Sperm Whale, a vast plaited forehead containing the highly-prized spermaceti, in its absolutely pure, limpid, and odoriferous state. A large whale's case generally yields about five hundred gallons of sperm, though considerable of it is lost in the ticklish business of securing what you can. In decapitating the whale, the operator has to be uncommonly heedful.