x CONTENT* l)l' THE Al'l'KNDIX. 



CHAPTER IX. 



ON THE ELECTROMOTIVE POWER OF HEAT. 



Object of the Memoir. Experimental Arrangement to determine the Electromotive Power. Temperatures 

 calculated from Quantities of Electricity. Increase of Tension with Increase of Temperature. Depends 

 on increased Resistance to Conduction. Quantity of Electricity independent of heated Surface. In Ther- 

 mo-electric Piles, the Quantity of Electricity proportional to trie Number of Pairs. Best Forms of Con- 

 struction of Thermo-electric Pairs . Page 90 



CHAPTER X. 



EXPERIMENTS ON THE CHEMICAL ACTION OF SOLAR LIGHT. 



Action of Absorbent Media. Ideal Coloration of the Chemical Rays. Specific Absorption. Colorific Ab- 

 sorption. Calorific Absorption. Specific Absorption of the Chemical Rays. Effect of Yellow Solutions. 



Decomposition of Carbonic Acid by Leaves. Penetration of Dimensions in Gases. Decomposition of Car- 

 bonic Acid under various coloured Media. Gas from Leaves contains Nitrogen. Chemical Rays of dif- 

 ferent Colours. Identity of Volume in the absorbed and evolved Gas. Cause of the Decomposition. 



Kilter's Experiments of the Non-oxygenation of Phosphorus. 



Decomposition of the Salts of Silver. Prismatic Spectrum on Bromide of Silver. Interference of Chemical 

 Rays. gaits decomposed by Light. Moonlight and Artificial Flames are inactive. 



Of Perihelion Motions. Dew of Water and Mercury. Iodine. Chloride of Gold. Non-deposition on a 

 Glass Plate. Current Action. Action of Flame. Action of Metal Screens. Protecting Action of a 

 Metal Ring. Is there Electricity in the Solar Ray ? 



Cause of the Green Colour of Leaves. Plants grow in Lights of various Colours. Seeds also germinate in 

 Red, Yellow, and Blue Light. Chemical Rays of different Colours . . 99 



Note added to the foregoing Chapter. 



AN ACCOUNT OF SOME EXPERIMENTS MADE IN THE SOUTH OF VIRGINIA ON THE LIGHT OF THE SUN 133 



CHAPTER XI. 



ON THE PROCESS OF DAGUERREOTYPE, AND ITS APPLICATION TO TAKING PORTRAITS FROM THE LIFE. 



Daguerreotype Portraits from the Life first taken. Spectral Images. Preservation of the Sensitive Plate 

 increases the Sensitiveness. Modifications in the Daguerreotype Process. Moonlight, Artificial Light, 

 and Drummond's Light, are all Active. Description of the original Process of taking Portraits from the 

 Life .... 136 



CHAPTER XII. 



ON SOME ANALOGIES BETWEEN THE PHENOMENA OF THE CHEMICAL RAYS AND THOSE OF RADIANT HEAT. 



Object of the Memoir. On the Daguerreotype Process. Chemical Constitution of Daguerreotype Pictures. 

 Spectral Images. Film of Iodide torn ofT Mechanically. Iodine is not evolved, but corrodes the Plate. 

 The Chemical Rays are absorbed. The Photographic Effects are transient. The Chemical Rays are 

 not conducted. They become Latent. Optical Qualities control Chemical Action. The Active Rays 

 are absorbed, and the Complementary reflected. Relation of Optical Forces and Chemical Affinities 144 



Note added to the preceding Chapter. 



ON CERTAIN SPECTRAL APPEARANCES, AND ON THE DISCOVERY OF LATENT LIGHT . . 156 



CHAPTER XIII. 



ON A NEW IMPONDERABLE SUBSTANCE, AND ON A CLASS OF CHEMICAL RAYS ANALOGOUS TO THE RAYS OF 



DARK HEAT. 



Analogies between the Chemical Rays and Heat. New Nomenclature proposed. Tithonic Rays. In- 

 dependence of Tithonic Rays and Light. Independence of Tithonic Rays and Heat. Dark Tithonic 

 Rays . ... 158 



Note added to the preceding Chapter. 



ON THE RAPID DET1THONIZING POWER OF CERTAIN GASES AND VAPOURS, AND ON AN INSTANTANEOUS MEANS 



OF PRODUCING SPECTRAL APPEARANCES . . .165 



CHAPTER XIV. 



ON A NEW SYSTEM OF INACTIVE TITHONOGRAPHIC SPACES IN THE SOLAR SPECTRUM ANALOGOUS TO THE FIXED 



LINES OF FRAUNHOFER, AND ON THE TITHONOTYPE. 



Mode of Producing the fixed Lines. Description of them. Difficulty of obtaining them in the Yellow and 



Green. 

 Daguerreotypes are dotted Surfaces. Mode of copying them by the Tithonotype. Polarized Structure of 



the Daguerreotype Film .... .... . 169 



