198 PEARLS AND PEARLING 



The bleak is the only river fish in France that is not 

 used for food. They are very abundant in the Seine, 

 Marne, Moselle and Escaut Rivers. The fishermen use 

 nets and catch the fish by thousands as they travel in 

 shoals in the current. 



To obtain the ''Oriental essence," the fish are scraped 

 over a shallow tub containing a small amount of water. 

 The scales are then washed and pressed and the essence 

 settles to the bottom of the tub. It requires 20,000 bleak 

 fish to furnish one pound of the essence. The essence 

 is very brililant and if a drop of it is allowed to fall 

 upon water the guanine floats and spreads, exhibiting 

 many brilliant colors. 



The "Oriental" essence is packed in tin boxes with am- 

 monia and sent to Paris where it is used in manufactur- 

 ing the fish-skin pearls. Many of these imitations have 

 a very delicate cream color and simulate the oriental 

 pearls. They can be distinguished from genuine pearls 

 by their weight and glassy shine. 



Glass beads are very commonly used as imitation 

 pearls. Some are made of opal glass and covered with 

 several layers of isinglass with another coating of a mix- 

 ture of turpentine and copal and oil and afterwards a 

 thin layer of tinted soft enamel to give it oriency. Some 

 opal glass beads are treated with fluoric acid. They have 

 a ground glass appearance, however, which reveals their 

 nature. Hollow glass pearls can be distinguished in sev- 

 eral ways. They are usually coated on the inside and 

 filled with wax. The ink spot test is a good one. If a 

 small drop of ink is placed on one of these filled beads, 



