From the fish trade there is much animal protein, which is useless for food purposes and which, to avoid nuisance, it is necessary to convert promptly in fertilizers. During the herring season there is the disposal in this way of the heads, tails, and the guts. Many fish are incidentally caught which, being valueless as food, are yet useful as manure. After the extraction of oil from fish livers the residue is suitable for a similar purpose. These residues are steamed, dried, and ground up, forming fish manure, rich in nitrogen and often also in phosphate. REFERENCES. "Chemical Fertilizers and Parisiticides," S. H. Collins, M.Sc. "Organic Nitrogen Fertilizers," Part III., Section II., p. 105. "Fish Manure," p. 110. INDEX Acclimatization in colloid systems, 236 Acid, ellagic, 29 gallic, 29 sulphurous, 227, 243 Acid process for bone gelatine, 243 Acids, for deliming, 23 for pickling, 114 in sour liquors, 29, 44 Adsorption, law of, 43 methods of clarification, 234 nature of, 41 of ions by gelatine, 211 African hides, 15 Albumins, 4, 240, 274, 277 Algarobilla, 32 Alum, 236, 240 American hides, 14 Animal excreta, 279 Arsenic sulphide, 20 Asiatic hides, 14 Astringency of liquors, 44 Bacteria in soaks, 16 limes, 20 bates, 24 tan liquors, 29 Bag leather, 86 Band-knife splitting, 52 Bark, hemlock, 34, 40 mallet, 34 mangrove, 35, 41 mimosa, 33 oak, 34 pine, 34, 41 willow, 32 Basic dyestuffs, 97 Basils, 115 Bating, 24, 94 Belting leather, 65 Blair-Campbell evaporator, 249 Bleaching leather, 62 glue, 241 Block Gambier, 40 Bloom, 29 Boiling process for glue, 223 Bone gelatine, 223 manure, 273 meal, 224 Bones, 223 Bookbinding leather, 104, 106, 117, 120 Boric acid, 23 Bottle tannage, 103 Box calf, 156 Bridle leather, 71 British hides, 8 Brushing leather, 63 Buck leather, 181 Buff leather, 181 Buffing, 52 Burning in, 54 Butt, 22 Bye-products of the gelatine trade, 272 of the leather trades, 268 Calcium sulphydrate, 22 Calf skins, 76, 120, 156 Casein, 276 Cast glue, 257 Catechin, 32 Catechol tans, 32 Caustic soda, 18, 20 Centrifugal fan, 50 Chamois leather, 181 Cheeks, 268 Chemistry of colloids, 201 Chestnut extract, 36 Chlorine bleach for glue, 246 Chrome calf, 156 goat, 163 hide, 170 sheep, 163 Chrome tannage, 127-174 finishing operations, 153 general methods, 139 history of, 127 one bath, 149 special qualities of, 136 theory of, 129 two-bath process, 142 Clarification of gelatine, 234 Coefficient of conductivity, 253 Colloid chemistry, 201 Combination tannages, 191 Concentrated foods, 275 Condenser water, 251 Conductivity coefficient, 253 Continental hides, 14 Crown leather, 178 Cube gambier, 40