[CONTENTS.]

PART I.

THE SCIENCE OF PHOTOGRAPHY.

Page
Introduction[1]
CHAPTER I.
Historical Sketch of Photography[6]

CHAPTER II.

THE SALTS OF SILVER EMPLOYED IN PHOTOGRAPHY.

Section I.—The Chemistry of the Salts of Silver.—The preparation and properties of the Nitrate of Silver—of the Chloride, Bromide, and Iodide of Silver.—The Chemistry of the Oxides of Silver[12]
Section II.—The Photographic Properties of the Salts of Silver.—The action of Light upon Nitrate of Silver—upon Chloride, Bromide, and Iodide of Silver.—The blackening of Chloride of Silver explained.—Simple experiments with sensitive Photographic Paper[18]

CHAPTER III.

ON THE DEVELOPMENT OF AN INVISIBLE IMAGE.

Simple experiments illustrating the process[25]
Section I.—Chemistry of the Substances, employed as Developers.—Development shown to be a process of reduction.—The chemistry of the principal reducing agents, Gallic Acid, Pyrogallic Acid, and the Protosalts of Iron[26]
Section II.—The Reduction of Salts of Silver by Developing Agents.—Reduction of Oxide of Silver—of Nitrate and Acetate of Silver.—Varied appearance of Metallic Silver when finely divided.—The reduction of the Iodide and other Salts of Silver containing no Oxygen[30]
Section III.—Hypothesis on the Formation and Development of the Latent Image.—Explanation of the terms under- and over-exposure.—Diagram of Molecular change.—Moser's experiments on development.—Curious perversions of development[34]

CHAPTER IV.

ON "FIXING" the PHOTOGRAPHIC IMAGE.

Chemistry of the various substances which may be employed as Fixing Agents.—Ammonia, Alkaline Chlorides, Bromides, and Iodides.—Hyposulphite of Soda.—Cyanide of Potassium[41]

CHAPTER V.

ON THE NATURE AND PROPERTIES OF LIGHT.

Section I.—The compound Nature of Light.—Its decomposition into elementary coloured rays.—Division of these rays into Luminous, Heat-producing, and Chemical Rays[46]
Section II.—The Refraction of Light.—Phenomena of simple refraction by parallel and inclined surfaces.—Refraction from curved surfaces.—The various forms of Lenses.—The Foci of Lenses.—Formation of a Luminous Image by a Lens[49]

Section III.—The Photographic Camera.—Its simplest form.—The field of the Camera.—Chromatic aberration.—Spherical aberration.—The use of Stops.—The double, or Portrait combination of Lenses.—Variation between the Visual and Chemical Foci in Lenses[54]
Section IV.—The Photographic Action of Coloured Light.—Diagram of Chemical Spectrum.—Illustrative experiments.—Superior sensibility of Bromide of Silver to coloured light.—Mode in which dark-coloured objects are Photographed[60]
Section V.—On Binocular Vision and the Stereoscope.—Phenomena of Binocular Vision.—Theory of the Stereoscope.—Wheatstone's reflecting Stereoscope.—Brewster's Stereoscope.—Rules for taking Stereoscopic pictures[66]

CHAPTER VI.