Atlantic Ocean, profound depths of, north and south, ii. 49 foraminifera at great depths in the, ii. 49, 50 Atmolysis, or method of analysing gases, i. 111 Atmosphere, effect of the heat radiated by the moon on the higher regions of the, i. 55 opalescence of the, and its effect on the chemical power of the sun’s light, i. 55 causes of this opalescence, i. 55 its permeability to every kind of chemical rays, i. 58 Atmosphere of the sun, thirteen terrestrial substances in the, i. 59 Atolls, or coral lagoons, ii. 140 Atoms or molecules of matter, power of atoms of matter on the rays of the solar beam, i. 58 aggregation of matter by electricity, i. 74 effect of the physical forces on molecular arrangement, i. 90, 91 proof of the individuality and polarity of the atoms of matter, i. 91 effect of motion, i. 91 Atoms: effect of catalysis, i. 91 of matter, i. 2 cohesion of, i. 25 unit of mechanical force, i. 26 the atomic theory, i. 93 the law of definite proportions, in combination and resolution of the component parts of substances, i. 94 affinity of kind and of degree, i. 95 force of chemical combination, i. 97, 98 relative atomic weights, i. 99 table of atomic weights compared with that of hydrogen, i. 100 relation between the atomic weights and the specific gravities of substances, i. 100 capacities of atoms for heat and electricity, i. 100, 101 law of equivalency in weight and volume, i. 102, 103 substitution the basis of this law, i. 104 sequence of atomic numbers, i. 105 groups of substances whose atomic weights are in regular arithmetical series, i. 106 groups of combined atoms called compound radicles, i. 106 the polyatomic theory, i. 107 the force of molecular attraction more powerful than gravitation, i. 109 internal movement of molecules of matter in a gaseous state, i. 113 Aulocantha scolymantha, structure of, ii. 21 Avicula margaritacea, or pearl oyster, nacreous lining of shell of, ii. 234 Azores, the black mildew of the, i. 297 Azote in vegetable organisms, i. 423 Azuline dye, production of, i. 123 B Babylon, the asphaltic mortar used in building, i. 126 Bacillaria cursoria, motion of, i. 203 Bacillaria paradoxa, motion of, i. 203 Back, Sir George, his arctic journey, i. 308 Bacteria, their structure, size and habitat, ii. 64 Bæomyces, structure of, i. 306 Balanidæ, structure of, ii. 213 Balanus balanoïdes, development of, ii. 216 Balanus culcatus, structure of, ii. 213-215 Baldness caused by fungi, i. 275 Balms, chemical combination forming the principle of the, i. 97 Bamboo, size and structure of, i. 386 Bangia, characters of the genus, i. 222 Bangia ceramicola, structure and mode of reproduction of, i. 223 Bangia ciliaris, structure and reproduction of, i. 223