224 THE WEALTH OF THE SEA 



odor, for if unspoiled fish waste or trimmings from 

 salted fish is used in its manufacture, the product 

 does not possess an unpleasant smell. 



The best grade of liquid glue is the one known as 

 skin glue. This glue is prepared from the skins of 

 salted cod and cusk. The second-best grade is pre- 

 pared from the skins of salted haddock, hake, and 

 pollack, mixed with trimmings from all kinds of 

 salted ground-fish (cod, cusk, haddock, pollack, and 

 hake). This grade is known as waste glue. 



The same general process is used in the manufac- 

 ture of both of these grades of glue. First the stock 

 is thoroughly washed with fresh water. This opera- 

 tion is accomplished by placing the stock in a large 

 circular tank, covering it with water, and rolling it 

 with a heavy wooden roller. The stock must be washed 

 for at least twelve hours in order to remove all the 

 salt. When it is completely freshened the stock 

 is thrown into steam- jacketed, false-bottomed, 

 rectangular galvanized iron cookers, where it is 

 covered with water and then heated with steam. After 

 about six hours the steam is shut off and the glue 

 liquor drawn off. The stock is then cooked a second 

 time. 



The glue liquors, formed by the solution of the 

 fish in hot water, are strained through excelsior, and 

 then evaporated to a viscous syrup. After evapora- 

 tion the glue is preserved by the addition of phenol 

 and some essential oil such as camphor or sassafras. 



Fish-head glue is made by washing and cooking 

 fish heads. The fresh heads and backbone of cod, 

 cusk, haddock, hake, and pollack are principally 



