Calendar: 1859-1860 Page 120

120 APPLIED SCIENCES rating Action of Organic Matters &c -Explanation of the Changes Phenomena of the Development of an Invisible Image -Illus- trations of Molecular Changes-Moser's Experiments-Reduc- tion of Oxides to the Metallic State Photographic Action of Coloured Light -Blue Red and Yellow Glasses-Flowers of Various Tints-Surface Reflection of White Light APPARATUS AND CHEMICALS The Camera -Rigid and Folding Cameras-Swinging Backs -Fowkes's Portable Camera Lenses -The Double Combination-the Single Achromatic Lens-Use of Diaphragms Collodion Its Nature and Mode of Preparation-Varieties of Pyroxyline-Glutinous and Fluid Collodion-the Iodizing Solution-Explanation of Changes which ensue on mixing The Nitrate Bath -Purification of Commercial Nitrate of Silver-Mode of Saturating with Iodide-Use of Litmus Papers for Testing Developing Solutions -Protonitrate of Iron for Positives- Sulphate of Iron-Pyrogallic Acid-Mode of testing Purity of Water and of separating Lime Salts when present THE POSITIVE PROCESS ON GLASS Cleaning the Glasses -With old Collodion-with Tripoli and Ammonia-with Nitric Acid to remove Iron Stains Preparing the dark Room -Its Illumination by Yellow Light -Arrangement of Apparatus Manipulations Sfc -The Collodion-Use of Bromide-Free Nitric Acid in the Bath-Effects of Under and Over-Exposure in the Camera-Excessive and Deficient Development-Fixing Varnishing &c COLLODION NEGATIVES Ihe Collodion and Bath -Iodide of Cadmium as an Iodizer -its Advantages and Defects-Iodide of Potassium-Inju- rious Action of Nitric Acid in the Bath-Effect of Acetate of Soda-of Glycyrrhizine and Organic Bodies in the Collodion -Decomposition of Collodion by keeping