The object of this little Manual is to present, in as plain, clear and concise a manner as possible, the _practice_ of a Collodion Process. This beautiful acquisition to a "sun-pencilling" was first given to the public by Mr. Frederick Scott Archer, an English gentleman, who alone is entitled to the credit, and deserves the esteem of every lover and practitioner of the Art, for his liberality in _giving_ it to the world. The Process here presented has never before appeared in print, and has been practised with the most eminent success by those who have been enabled to adopt it. All reference to the various systems or methods of manipulation, by the thousands of practitioners, has been excluded, and one Process given. I conceived that this was the better plan to adopt, thus leaving the mind of the learner free from confusion, and pointing out one course, which, if carefully followed, will produce good and pleasing results. I have also presented a list of all Patents upon the Collodion Process; this will give all an opportunity of choosing their own course in regard to the respect they may conceive to be due to such Patent Rights. S. D. H. CONTENTS. ~~~~~~~~~~ PART I. CHAPTER I. Introduction--Light--Solar Spectrum--Decomposition of Light--Light--Heat and Actinism--Blue Paper and Color for the Walls of the Operating Room--Proportions of Light, Heat and Actinism composing a Sunbeam--Refraction--Reflection--Lenses--Copying--Spherical Aberration--Chromatic Aberration 13 CHAPTER II. Camera--Arrangement of Lenses--Camera Tubes--Camera Boxes, Bellows, and Copying--Camera Stands--Head Rests--Cleaning Vice--Nitrate Bath--Leveling Stands--Printing Frames--Collodion Vials 26 PART II. =Practical Hints on Photographic Chemistry.= CHAPTER III. Soluble Cotton--Manipulation--Plain Collodion--Bromo-Iodized Collodion for Positives--Ditto for Negatives--Solution of Bromide and Iodide of Potassium and Silver--Double Iodide of Potassium and Silver--Developing Solution--Fixing the Solution--Brightening and Finishing the Image--Photographic Chemicals 41 PART III. =Practical Details of the Positive or Ambrotype Process.= CHAPTER IV. Lewis's Patent Vices for Holding the Glass--Cleaning and Drying the Glass--Coating--Exposure in the Camera--Developing--Fixing or Brightening--Backing up, &c. 129 PART IV. =Practical Details of the Negative Process.= CHAPTER V. Negative Process--Soluble Cotton--Plain Collodion--Developing Solution--Re-Developing Solution--Fixing the Image--Finishing the Image--Nitrate of Silver Bath 143 PART V. =Practical Details of the Printing Process.= CHAPTER VI. Printing Process--Salting Paper--Silvering Paper--Printing the Positive--Fixing and Coloring Bath--Mounting the Positive--Facts worth Knowing 151 CHAPTER VII.