THE HERRING. 345 
are made of oak—for other woods impart a flavour to the fish— 
each layer being completely covered with salt. Red herrings are 
those which are opened and then smoked. 
In 1862, the Norwegian fisheries produced 659,000 tons of 
herrings; about a quarter of this was used for home consumption, 
and the rest exported, bringing a return of about £360,000. 
Oil can be extracted from the herrings as well as from the 
whales. They are boiled for five or six hours in fresh water, and 
upon cooling the oil rises to the surface. It is purified by filter- 
ing, or by simple decantation, and then put into barrels. The 
residue is called fangrum, and is considered an excellent manure. 
