Preface 



Twenty-seven years ago the senior author with the help of a number of collab- 

 orators wrote the first edition of "Marine Products of Commerce," one of the first 

 treatises in which the technology of all the commercial products of the sea was 

 considered. Great advances have been made in the technology of fishery and other 

 marine products during the past quarter century. Consequently, preparation of 

 this second edition has necessitated rewriting almost the entire book. Only two 

 chapters, those on Sponges and Fish Glue, remain substantially unchanged. 



Entirely new industries have arisen since the publication of the first edition, 

 as for example the extraction of magnesium and bromine from sea water and the 

 making of vitamin concentrates from fish-liver oils. Because of the importance of 

 the magnesium and bromine industry, an entire chapter has been devoted to it. 

 The manufacture of chemicals from sea water is an industry that is likely to be- 

 come more and more important in the future. Our rapidly increasing knowledge 

 of chemistry will make possible the perfection of methods of separating other 

 substances from the sea, the great storehouse of water-soluble chemicals. 



Another new industry which is considered in detail in this new edition is the 

 marketing of packaged fish fillets and steaks. The preparation, packaging, freez- 

 ing and marketing of fish fillets is now one of the most important fishery in- 

 dustries. In 1923 freezing by immersion in or spraying with brine was the only 

 known method of quick-freezing fish. Since then many new and superior methods 

 of rapidly freezing fish and fishery products have been perfected and are now 

 being used. These methods are described and discussed herein. 



Great improvements have also been made in equipment used for the transporta- 

 tion of both fresh and frozen fishery products. In 1923 little was known about the 

 refrigeration of motor trucks and trailers. Today immense quantities of fresh and 

 frozen fish and shellfish are shipped in refrigerated trucks which often transport 

 these products a thousand miles or more. Because of the importance of the re- 

 frigerated transport of perishable fishery products in making available fish and 

 shellfish of excellent quality throughout the United States and Canada, an entire 

 new chapter is devoted to this subject. 



The marine algae or seaweed industry has also been undergoing startling 

 changes. In 1923, seaweeds were used principally for human food and agar in 

 the Orient, for the making of iodine and potash in Norway, Japan and a few 

 other countries, for fertilizer and for stock food. Since then the making of iodine 

 and potassium salts from seaweeds has become almost a thing of the past. On 

 the other hand, the manufacture and use of seaweed extractives has become an 

 important industry in America and certain parts of Europe. Irish moss ex- 

 tractives and alginates, prepared from laminaria and giant kelp, are being used 

 extensively in many important food products and for many industrial purposes. 



