Chemical conception of material changes, 177. Chemistry, aim of, 9, 26, 160. ---- change from alchemy to, 126. ---- methods of, 10. ---- probable origin of word, 24. Classification, alchemical methods of, 59. Colours, Lucretius' explanation of differences between, 18. Combustion, 141. Compounds, chemical conception of, 171. Conservation of mass, 164. Curie, her discovery of radium, 182. Dalton's additions to the Greek atomic theory, 21, 172. Democritus, his saying about atoms, 15. Dephlogisticated air, 147. Destruction, thought by alchemists to precede restoration, 65, 127. Electrons, 187-189, 197, 198. Elements, alchemical, contrasted with chemical, 165; radio-active substances contrasted with, 190-192. ---- the alchemical, 49, 54, 60. ---- the chemical, 61, 62, 161. ---- use of word, by phlogisteans, 133. Essence, the alchemical, 32, 35, 49, 58, 72. Fire, different meanings of the word, 53. Gates, the alchemical, 69. Gold, considered by alchemists to be the most perfect metal, 40, 45. Greek thinkers, their atomic theory, 15. Hermes Trismegistus, 37. Kathode rays, 188. Language of alchemy, 96. ---- purposely made misleading, 36. Lavoisier on calcination, 153, 155. ---- his use of word _element_, 194. ---- his use of word _principle_, 163, _note_. ---- on object of chemistry, 160. ---- on oxygen, 155. ---- on systems in science, 163. ---- on the principle of acidity, 59, 155. ---- on the reactions of metals with acids, 158. ---- on the transmutation of water to earth, 152. Lockyer, on spectra of elements, 181. Lucretius, his theory of nature, 16. Magic, characteristics of, 23, 24. Material changes, Greek theory of, 15. Metals, alchemical connexion between, and plants, 34. ---- compared by alchemists with vegetables, 33. ---- mortification of, 65. ---- seed of, 34. ---- their desire to become gold, 40. ---- transmutation of, 33, 39, 46. Natural state of bodies, 39, 43. Oxygen, 144, 145. Paracelsus, his description of alchemists, 25. ---- his distinction between natural and artificial mortification, 65. ---- sketch of life of, 117. Pelican, 92. Perfection, alchemical teaching regarding, 27, 40. Phlogistic theory, 133, 139. Phlogiston, 126, 130, 137. Priestley, his discovery of oxygen, 144. Principles, the alchemical, 49, 51, 54, 60, 133. ---- Lavoisier's use of the word, 163, _note_. Radio-active substances, are they elements? 191, 194, 195; properties of, 185-187. Radio-activity, characteristics of, 183, 184; of radium, 186; of thorium, 193; of uranium, 193. Radium, emanation of, 187; heat from, 186; rays from, 186. Ramsay, on transmutation of elements, 199. Regimens, the alchemical, 72. Sacred art, the, 122. Scientific theories, general characters of, 21, 150. Seed, alchemical doctrine of, 56. Seeds of metals, 34. Simplicity, asserted by alchemists to be the mark of nature, 28, 38. ---- is not necessarily the mark of verity, 138.