Algæ, i. 179 classification of the group, i. 179-181 green Algæ, i. 181-220 zones or degrees of depth at which different Algæ exist, ii. 221, 258, 259 brackish water often a cause of change in the form of Algæ, i. 245 colossal Algæ of the North Pacific, i. 245 rings of growth of some of the larger sea-weeds, i. 252 Alizarine blue, from what obtained, i. 124, 125 Alkalies, their affinity for acids, i. 96 Alkaloids, chemical structure of, i. 427 Allosorus crispus, or parsley fern, structure and habitat of, i. 358 Allotropism, i. 8 of carbon, i. 15 Alsophileæ, structure of, i. 360 Alum, a free radiator but a bad conductor of radiant heat, i. 37 partial decomposition of, by diffusion, i. 109 manufacture of, i. 120 Alumina, effect of electricity on, i. 32 Aluminum, i. 4 spectrum of, i. 65 Amalgams of metals, illustrating the relation between chemical affinity and mechanical force, i. 98 Amansia, structure of, i. 242 Amaryllidaceæ, structure and mode of reproduction of, i. 388 America, North, enormous quantities of petroleum in, i. 126 Amidogen combines with other substances and simple atoms as if it were a simple element, i. 106 Ammonia, amount of absorption of radiant heat by, i. 41 characteristics and constituents of, i. 119 chemical composition of, i. 128 combination forming, i. 107 carbonate of, i. 119 extent of the manufacture of, i. 120 muriate of, i. 120 manufacture of, i. 120 sulphate of, i. 120 how manufactured, i. 120 Ammonium, sulphide of, i. 119 Amœba princeps, structure, motions, food, and reproduction of, ii. 13-16 its capture of the Actinophrys, ii. 18 a new species found in dust from Egypt, ii. 65 Amorphous substances, conduct of, under magnetic influence, i. 76 Amphicora, two eye-specks in the tail of, ii. 158 Amphidetus, spines of the, ii. 180 Amphipoda, characters of the, ii. 201 Amphithoæ, structure of, ii. 203 Analysis, chemical, electricity and light instruments of, i. 95 the most powerful means of, i. 96 Andræa subulata, leaves of, i. 330 Andræaceæ, characters of the tribe, i. 328 Angiocarpei, structure, mode of reproduction, and habitat of, i. 309, 310 Angiopteris evecta, perfume from, i. 364, 365 Angræcum sesquipedale, structure and mode of reproduction of, i. 402 Anguillulæ, eel-like entozoa, structure and habitat of, ii. 147, 148 Anemone, sea, structure and mode of reproduction of, ii. 130, 131 Aniline, formation of the fulminate of, i. 92 combination forming, i. 107 how produced, i. 121, 122 constituents and characteristics of, i. 122 formation of the aniline colours, i. 122, 123 mauve, i. 122 magenta, i. 122 purple, i. 123 yellow, i. 124 chemical composition of, i. 128 Aniline, acetate of, i. 123