200 The Comme7xial Prodttds of the Sea. 



foundland. More than 350 vessels are engaged in it. The 

 seals whelp their young in January and February on the 

 ice field of Labrador ; this ice is floated southwards by 

 the ocean currents, and is always to be found on the coast 

 of Newfoundland after the middle of March. The take of 

 seals varies ; in some years the export of skins being under 

 200,000, in others exceeding 450,000. The value of the 

 seal oil shipped ranges from ;^ 160,000 to ;^"200,ooo. The 

 yield of oil is about 11 gallons from one cwt. of blubber. 



Fig. II. 



Phoca Groenlandica. 



Seal oil and cod oil are now two of the most important, 

 whale oil having much declined in quantity, owing to the 

 fishery being less earnestly prosecuted ; but there are very 

 many fish oils, extracted in different quarters, which have 

 a local and general use, such as shark oil, herring oil, men- 

 haden oil, etc. . 



Seal Oil. — There are three classifications of seal oil : 

 that which drains spontaneously by the pressure of the 

 layers of the skins one over the other ; that which is pre- 

 pared by submitting the fat to the action of steam in 

 hermetically closed boilers ; and that which is obtained from 

 the residual mass, submitted to a high pressure. 



