CHAPTER VI.

THE PHOTOGRAPHIC PROPERTIES OF IODIDE OF SILVER UPON COLLODION.

Section I.--_Collodion._--Pyroxyline--its varieties--its chemical composition.--Means of obtaining Nitro-Sulphuric Acid of the proper strength.--Solvents for Pyroxyline.--Variation of physical properties in different samples of Collodion.--The changes which Iodized Collodion undergoes by keeping 75

Section II.--_The Chemistry of the Nitrate Bath._--Its solvent action on Iodide of Silver.--Acidity and Alkalinity of the Nitrate Bath.--Formation of Acetate of Silver in the Bath.--The substances which decompose the Bath.--Changes in the Nitrate Bath by use 86

Section III.--_The Conditions which influence the Formation and Development of the Latent Image._--Causes which increase or diminish the sensitiveness of the film to Light.--Conditions which hasten or retard development 91

Section IV.--_On certain irregularities in the Developing Process._--Effect of particular states of the Bath, and of the Collodion, in producing clouding of the Image, and of acids in obviating it 103