112 THE WEALTH OF THE SEA 



under water, the lustrous particles are suspended 

 in the liquid. The crude liquor so obtained is strained 

 through cheese-cloth and allowed to settle. After the 

 crude essence has been washed several times by decan- 

 tation, strong ammonia is added and the essence is 

 allowed to stand for a considerable time to permit 

 the digestion of the proteinaceous material. The 

 concentrated suspension is pearl essence. 



By other improved methods the lustrous crystals 

 are suspended in acetone, amyl acetate, or other 

 organic solvents, which are solvents of the nitrocel- 

 lulose or cellulose acetate lacquer. Pearl essence lac- 

 quer possesses many advantages over the aqueous 

 suspension, as it may be applied with a brush as 

 ordinary lacquer. 



Various grades are made, the distinction resting 

 upon freedom from color and upon the fineness of 

 the crystals. The best pearl essence possesses a bril- 

 liant luster and when slightly agitated gives a unique 

 and most beautiful "whorly effect." The most desir- 

 able colors are silvery white and slightly pink. Gray 

 or brown shades of color are undesirable. The better 

 qualities of pearl essence have uniformly small crys- 

 tals. The crystals are roughly proportionate to the 

 size of the fish from which they are obtained. Those 

 from the herring and alewife are smaller and make 

 a fine-grain essence of higher quality than those 

 obtained from the shad. 



In making the wax-filled beads, the essence is 

 allowed to settle, the ammonia is decanted off, and 

 pure gelatin or fish-glue is put in, so that a con- 

 centrated gelatin solution is made; an antiseptic is 



