...And it's more than a drug if you're interested in chemistry. Why bromine and other stuff such as color 'couplers' are added to B&W silver halide emulsions to

...And it's more than a drug if you're interested in chemistry. Why bromine and other stuff such as color 'couplers' are added to B&W silver halide emulsions to make them panchromatic as well as faster and more sensitive is complicated enough, but the chemistry that goes into making either a color (masked) negative (Kodacolor, Eastmancolor etc.) or a reversal colour emulsion such as Ektachrome, is a whole new ballgame. Processing the film may be comparatively easy but deep down color emulsions are a true wonder of chemical engineering. Not only do chemists have to be familiar with color theory but also they have to find stable color coupling dyes that bond with the silver halides (a difficult task with many compromises) as well as work through a reversal process and still remain stable not to mentioned the fact that this has to be compatible with the separate process of 'doping' emulsions to both increase and balance the speeds of the layers (each of which is different). Optimizing each of these competing demands is almost a complete branch of chemical engineering itself. If that's not enough, couple it all with the the need to stop color cross-coupling between layers (which is akin to cross-modulation in signal processing and muddies colors and which cannot be removed by simple color balancing)—and the incorporation of stabilizers whilst simultaneously keeping the silver halide crystals very small throughout the process (to reduce grain)—and also the incorporation of chemicals to prevent and mold etc. Even then that's not the end of the story. It's a great shame that most photographers haven a clue what a gem of technology that's in their possession when clasping a roll of 36 exposure color film. Now don't think that that the chemical technology of color film is now obsolete as it isn't. Even if color films were now a complete dead end each of its chemical processes live on in other areas of chemistry.