A Manual of Photographic Chemistry, Including the Practice of the Collodion Process
CHAPTER VII.
ON POSITIVE AND NEGATIVE COLLODION PHOTOGRAPHS.
Definition of the terms Positive and Negative.--The same Photograph often capable of representing both varieties 106
Section I.--_On Collodion Positives._--The Collodion and Nitrate Bath best suited for Positives.--Peculiarities of Pyrogallic Acid, and the Protosalts of Iron employed to develope Collodion Positives.--The colour of Positives affected by the length of exposure to light.--A Process for whitening Glass Positives by means of Bichloride of Mercury 108
Section II.--_On Collodion Negatives._--The Collodion and Nitrate Bath best adapted for Negatives.--Use of Glycyrrhizine to increase the intensity.--Developing solutions for Negatives.--Conversion of finished Positives into Negatives 113