When we think of Victorian photography, we picture silver-plated daguerreotypes and grim-faced portraits on glass. But in 1891, the Parisian-born photographer Peter C. Duchochois published an entire practical treatise devoted to silverless photography — processes that used iron, uranium, platinum, chromium, and, most curiously, textile dyes to capture images in light.

Duchochois's table of contents alone reads like a lost workshop manual:

The Primuline Process. Preparation of the materials, cotton, paper, etc. — The reagents employed to obtain various colored proofs... Printing ON Wood, canvas, opal and glass plates, transparencies... Tracing on Metal... Graphotypy

The Primuline Process is the standout. Primuline was a sulfur-containing yellow dye discovered in 1887 by A.G. Green — cheap, cheerful, and originally sold to color cotton. Green quickly noticed something remarkable: fabric dyed with primuline could be diazotized, exposed under a negative in sunlight, and then developed in a chemical bath to yield permanent images in whatever color the developer specified. Red, orange, brown, blue, purple — an entire darkroom in a bottle. Duchochois's chapter title promises exactly this: "The reagents employed to obtain various colored proofs."

Modern chemistry vindicates the technique completely. Primuline diazo printing was the direct ancestor of diazotype — the blueprint's less-famous cousin — and of the ammonia-developed "whiteprint" machines that dominated architectural offices from the 1920s until the desktop plotter finally killed them in the 1990s. If you have ever smelled the sharp ammonia tang wafting out of an old blueprint shop, you were smelling Green's chemistry at work.

What was truly lost is the craft side. Duchochois describes printing photographs directly onto cotton, wood, canvas, opal glass, and metal plates — no silver, no darkroom voodoo, no imported chemistry. A rural draughtsman in 1891 could sensitize a bolt of cotton on his kitchen table, pin a leaf or a hand-drawn negative to it, leave it in the sun for an afternoon, and rinse out a permanent multicolor image. Craft revivalists have quietly resurrected cyanotype (the blueprint) as a fabric art, but primuline printing — with its full color palette — has almost entirely vanished from the how-to literature.

Duchochois was writing for "Photographers, Architects, Engineers, Draughtsmen, and Wood and Metal Engravers" who couldn't afford a proper silver darkroom. His book is a snapshot of an era when photography was a democratic, kitchen-chemistry craft — before Kodak's slogan "You press the button, we do the rest" turned it into a consumer product and quietly buried the dozen weirder ways of catching light on a surface.