Wonders of chemistry--Origin, progress, and objects of alchemy--Art of breathing fire--Employed by Barchochebas, Eunus, &c.--Modern method--Art of walking upon burning coals and red-hot iron, and of plunging the hands in melted lead and boiling water--Singular property of boiling tar--Workmen plunge their hands in melted copper--Trial of ordeal by fire--Aldini’s incombustible dresses--Examples of their wonderful power in resisting flame--Power of breathing and enduring air of high temperatures--Experiments made by Sir Joseph Banks, Sir Charles Blagden, and Mr. Chantrey 227 LETTER XIII. Spontaneous combustion--In the absorption of air by powdered charcoal--and of hydrogen by spongy platinum--Dobereiner’s lamp--Spontaneous combustion in the bowels of the earth--Burning cliffs--Burning soil--Combustion without flame--Spontaneous combustion of human beings--Countess Zangari--Grace Pett--Natural fire-temples of the Guebres--Spontaneous fires in the Caspian Sea--Springs of inflammable gas near Glasgow--Natural light-house of Maracaybo--New elastic fluids in the cavities--of gems--Chemical operations going on in their cavities--Explosions produced in them by heat--Remarkable changes of colour from chemical causes--Effects of the nitrous oxide or Paradise gas when breathed--Remarkable cases described--Conclusion 313 LETTERS ON NATURAL MAGIC; ADDRESSED TO SIR WALTER SCOTT, BART. LETTER I. Extent and interest of the subject--Science employed by ancient governments to deceive and enslave their subjects--Influence of the supernatural upon ignorant minds--Means employed by the ancient magicians to establish their authority--Derived from a knowledge of the phenomena of Nature--From the influence of narcotic drugs upon the victims of their delusion--From every branch of science--Acoustics--Hydrostatics--Mechanics--Optics--M. Salverte’s work on the occult sciences--Object of the following letters. MY DEAR SIR WALTER, As it was at your suggestion that I undertook to draw up a popular account of those prodigies of the material world which have received the appellation of _Natural Magic_, I have availed myself of the privilege of introducing it under the shelter of your name. Although I cannot hope to produce a volume at all approaching in interest to that which you have contributed to the Family Library, yet the popular character of some of the topics which belong to this branch of Demonology may atone for the defects of the following Letters; and I shall deem it no slight honour if they shall be considered as forming an appropriate supplement to your valuable work.