6 REPORT OF THE COMMISSIONER OF FISHERIES. 



of oil, (h) steaming, and (c) canning raw after removal of excess 

 water by brining and partial drying. A pack that appeared to be 

 equal, if not superior, to any fried-in-oil product was made by a 

 modified steaming process. Quite satisfactory products were pre- 

 pared by the raw-pack method; that is, preliminary brining and 

 drying, followed by sealing and processing. Good packs also were 

 prepared by the method of cooking in brine, but this may perhaps be 

 adjudged an unsatisfactory method because of the penetration of 

 too much salt. 



SALTING OF PACIFIC COAST MACKEKEI-. 



Attention was given by the San Pedro laboratory to the salting of 

 the Pacific Coast mackerel {Scomher japonicus). This fish is, in 

 general, less fat than the Atlantic mackerel and its flesh is more 

 likely to be dark in color. It was found, however, that the method that 

 previously in the bureau's salting experiments had been found to 

 be applicable to other fish in warm climates was here successful. 

 This process consists in using high-purity salt applied dry to per- 

 fectly fresh fish that have been thoroughly cleaned of all blood and 

 viscera. These points all seem to be essential. Packers, who have 

 themselves hit upon most of these points, have found by experience 

 that salt of inferior quality produces inferior fish and that any 

 blood left in the fish darkens it. Freshness is also important, so 

 much so that salting aboard the boats seems advisable. 



PEARL ESSENCE. 



Pearl essence, an incidental product of the fisheries, has continued 

 to attract considerable attention, perhaps more because of its spec- 

 tacular beauty and novel application than because of its industrial 

 importance. Nevertheless, the business of manufacturing imitation 

 pearls, which was at one time an exclusively European and Japanese 

 industry, has migrated to America to a 'very large extent. New 

 York City and its vicinity are now the center of a considerable 

 imitation-pearl industry, based largely on the supply of pearl 

 essence produced in the United States principally from herring and 

 alewife scales. 



A process of making a pearl essence has been elaborated in the 

 fishery products laboratory which, in technique, is a radical de- 

 parture from any methods known to have been used hitherto. By 

 this method the lustrous material from the scales is removed in 

 water, together with any dirt, blood, slime, etc., that may accom- 

 pany the scales. The crude suspension is then treated chemically 

 in such a way that the lustrous or nacreous particles are removed 

 bodily from the crude liquor and transferred to ether and then to 

 ethyl or amyl acetate, which are solvents of nitrocellulose, which, 

 when dissolved in the suspension, makes a pearl lacquer. This 

 applied to glass beads makes the "indestructible" pearl of com- 

 merce. "Essence" has been prepared by this process from the 

 scales of numerous species of fish. The details of the process wiU 

 be published in a separate document. 



