214 The Commercial Products of the Sea. 



of tinned sheet iron. This tinned pot is then put into a 

 larger iron pot, half full of water, which on becoming 

 heated causes the livers immediately to begin to give out 

 their oil. Some makers introduce steam from a boiler 

 between the two pots, and others let the steam out directly 

 on the livers. The first yield by these methods of regu- 

 lated heat is removed by spoons, filtered when cold, and 

 reserved for medicinal use under the names of " steam- 

 boiled medicinal " and " ordinary bright." The after yield 

 is used in medicine, though somewhat redder; it is called 

 " bright brown." Finally, those portions of liver that 

 will not dissolve by themselves or by a mild heat are 

 roughly boiled down to yield "dark brown," or tanner's 

 oil, the black residuum being used with other fish refuse for 

 manure. 



There is a great difference between one year and 

 another in the quantity of oil the cod's liver yields. One 

 year it may require 600 livers to make a barrel of oil ; in 

 others, 200 are sufficient. 



In 1840 42,737 barrels of cod and shark oil were sent 

 away from Norway. In 1848 1,296,572 gallons of cod oil 

 were shipped, against only 65,600 in 1846. 



From the coast of Norway the average export of fish 

 oil from 1851 to 1855 was 52,900 tuns, and from 1856 to 

 1860, 59,617 tuns per annum ; from 1861 to 1866, 7,750,000 

 litres per annum. In 1877 130,600 barrels of cod-liver 

 oil were shipped, valued at ^3 86,600. The catch of each 

 boat yields from 8 to 20 barrels of liver. Fresh livers, 

 for medicinal oil, fetch from 27^. to 31^. per barrel; old 

 livers, from 22^. to 26^. At the early part of the season 

 the fish are rich in liver, so that from 250 to 300 of the 

 net-caught fish yield a barrel of liver, while 50 to 100 more 

 fish taken on lines would be required. As the season 



