THE BROWN ALGAE-ALGIN FROM KELPS AND FUCOIDS 



95 



silver, bismuth, antimony, zinc, cadmium, aluminum, chromium, uranium, barium, 

 calcium, and strontium. Insoluble alginates are also formed by solutions of the 

 following salts: stannous and stannic chloride, mercurous and mercuric nitrate, 

 ferrous sulfate, ferric chloride, and lead acetate. A solution of sodium alginate is 

 not precipitated nor coagulated by alkalies and salts of alkalies, including: 

 lithium, alkaline silicates, and potassium bichromate; sodium stannate, succinate, 

 biborate, and tungstate; magnesium and manganese salts, starch, glycerol, sucrose, 

 amyl alcohol; boric, acetic, carbolic, tannic, butyric, benzoic, galhc, pyrogallic, 

 arsenious, and succinic acids; mercuric iodide and chloride; and bromine, iodine, 

 and chlorine. Insoluble algin derivatives of metal (e.g., copper) form complexes 

 with ammonia and consequently can be dissolved in an ammoniacal solution. 

 Sodium alginate solutions are not coagulated by heat nor gelled by cooling. They 

 can easily be distinguished from gelatin since they are not precipitated by tannin. 



Table 21. Metallic Alginates. 

 Soluble Alginates ** f (Precipitated by Alcohol) 



* All the soluble alginates give more or less gloss to paper. 



f Hoagland, D. R., "Organic Constituents of Pacific Coast Kelps," /. Agr. Res., 4, 

 39-58 (1915). 



