Electricity, i. 30 permanent and regular current of, over the earth, in the atmosphere and in the surface of the earth, i. 31 thunder and lightning, i. 31 force exerted in the creation of the deep, i. 31 the voltaic battery and the electro-magnetic induction apparatus, i. 31, 32 reciprocity of action of electricity and heat, i. 31 electricity produced by chemical action, and conversely, i. 32 intensity of the light and heat of the electric spark, i. 32 produced by fifty Bunsen elements, i. 32 conducting power of charcoal, i. 32 air and glass non-conductors, i. 32 proof of the correlation of heat and electricity, i. 33 motion of the atoms of a conducting wire during the passage of an electric current, i. 33 effect on a conducting wire of an invariable transit of electricity sent from the same pole of an inductive apparatus, i. 33 difference between electric and magnetic currents, i. 33 influence of electricity on the aggregation of matter, i. 74 ratio between the specific heat and weight of the atoms of matter, i. 74 influence of magnetism on the stratified appearance of the electric light, i. 78 extreme heat and light of electric discharges, i. 84 the arc discharge, i. 84 cause of the stratified discharge, i. 85 effect of varied intensity on electric discharges, i. 86, 87 effect of varied resistance on electric discharges, i. 88, 89 varied facility with which substances transmit electricity, i. 90 illustration of the action of electricity and magnetism on light, i. 90 instances of the correlation of electricity and heat, i. 91 voltaic electricity, and its combination and resolution of substances according to the law of definite proportions, i. 94 Faraday’s law of the quantity of electricity required to separate and unite the same atoms, i. 94 superiority of voltaic over static electricity, i. 95 electricity the most powerful instrument of analysis, i. 95 capacity of atoms for electricity, i. 100 a given quantity of electricity required to separate combined substances into their component parts, i. 101 spectrum analysis of the electric spark, i. 138 development of electricity in plants and flowers, i. 430 electric currents in the nerves and muscles of animals, ii. 7 Electro-chemical action in heterogeneous atoms of matter, i. 95 Electro-magnetic induction apparatus, i. 31 Ruhmkorff’s, i. 32 Elvellacei, characters of the, i. 290 Empusa Muscæ, or fly fungus, i. 274 Encalypta vulgaris, organs of fructification of, i. 326 Encrinites, structure of, ii. 175 Endocarpei, structure and habitat of, i. 310 Endocarpon lacteum, structure and organs of reproduction of, i. 299 Endogenous plants, i. 383-403 Enteromorpha, characters of the genus, i. 223 Enteromorpha intestinalis, structure and habitat of, i. 223, 224 Entomostraca, characters of the, ii. 203