INDEX.

28& Magnets, attachraeut and repulsion of, 75. Maxwell, 141.] Mayer, 140. Mechanical energy changed into heat, 23. equivalent of heat, 43. force, 205. instability, 155. Mental forces, mutual correlations of, 227-236. Mind, its correlations to natural forces, 218-227. and body, 207, 211. Molar force, 205. Molecular attraction and heat, 55. separation, 80. Molecules, ultimate, of matter, 5. their motions, 7. and atoms, 51. Motion changed into an electric current, 99. Muscular power, 207. Xarcotic stimulants, 229. Negative and positive electricity, 63. Nerve power, 207. Newton, 136, 137. Non-couductors of electricity, 61. Percussion, 36. Perpetual motion, 139. Physical ibree, 194. Plants growing at night, 181 Positive and negative electrici+v, 63. Protoplasm, 177. Pulleys, their function, 30. Radiant energy, 81. converted into absorbed heat, 123. promoting chemical separa- tion, 123. Rankine, 141. Resinous and vitreous electricity, 63. Rotation of earth retarded, 95. Rumford, 39, 137. Silver oxide readily decomposed, 58. Solar rays, decomposition by, 59. Sulphur, 146. Sun — a source of high-temperaturfi heat, 148. Sun's heat, origin of, 150. spots, auroras, and cyclones correlated, 98. Tait, 141. Temperature of dissociation, 115. Thermo-electricity, 116. Thermopile, 117. Thomas Aquinas, 209. Thomson, William and James, 140. Tides, 146. Tissues, decay of, 164. Universe, its probable fate, 152 Units of heat and work, 46. Vegetation, 176. Velocity and energy, relation be- tween, 16. Virtual velocities, 34. principle of, its history, 137. Vital force, whence derived, 171. Vitality, 194. Vitreous and resinous electricity, 63. Voltaic current, 69. and magnetism, 72. heating eSect of, 73. chemical effect of, 74. Water at high level, 24. Watt, 138. Wild's electro-magnetic machine, 103. Will, 194. Work, definition of, J5. unit of, 15. rise of true conceptions r& garding, 138.

Yeast-plant, 185.