12 FISH ISINGLASS AND GLUE. 



ucts, and from ash. Fish glue is usually made up into liquid glue, 

 for which there is a reasonably large demand. The manufacture 

 of mucilage and pastes of various sorts from the dextrins obtained 

 from starch has largely limited the demand for fish glue so that 

 enterprises based solely on this product have not been very profitable. 



The manufacture of fish glue in this country has been confined 

 practically to three States, Massachusetts, Maine, and California, 95 

 per cent of the value of the product being credited to Massachusetts. 

 For 1908 the value of the entire output in the United States was 

 $631,000; the value of the New England output was $611,000 and of 

 the Pacific coast output $20,000. 



In New England fish glue is made from cod heads, skins and bones, 

 haddock residues, and all fish offal containing little or no oil, as this 

 constituent is fatal to the production of a good glue. The refuse 

 from salting factories forms«a very large part of the source of supply, 

 as salt codfish is prepared in considerable quantities in this region. 

 The refuse from sturgeon and the skins and scales of menhaden and 

 herring have been used. Green and Tower « have shown that 1 ton 

 of menhaden yields 20 pounds of dry scales from which 10^ pounds 

 of pure gelatin (containing 16 per cent moisture) may be obtained. 

 In this connection it may 'be noted that the adhesive qualities of the 

 " stick " obtained by the present methods of concentrating the waste 

 liquors of the menhaden industry are due to the large percentage of 

 gelatin present; this material as now manufactured has use only in 

 the fertilizer industry, as it contains too much salt, oil, and foreign 

 protein substance to be serviceable for glue. Many other fish residues 

 are now unutilized; such is the case of the mullet of the southern 

 waters, which yields an excellent quality of glue. 



In the last few years whale blubber has been utilized for the pro- 

 duction of glue. According to the German patent 131315, the blub- 

 ber is chopped up, freed from most of the fat by pressing m the cold, 

 and the remainder of the fatty matter is extracted by some solvent, 

 as benzene. By this method all the fat is recovered and a fat-free 

 dry residue consisting of tissue containing the gelatin is obtained, 

 and this may be readily converted into glue. 



Attempts to produce glue from the gray fish {Squalus acanthias) 

 have not been successful on account of the large amount ox oil and 

 water in the fish, the difficulties attended with the extraction of the 

 oil, and the presence of dark pigments in the skin which discolor the 

 extracts. It is also probable that the skeleton contains only a small 

 amount (if any) of collagen or glue-forming substance. The flesh 

 of the smooth grayfish (Mustelus cams) contains gelatin-forming 

 material and presents possibilities as a source of glue. 



oU. S. Fish. Com. Bull., 1001, p. 97-102. 



