'Pancho and Herman Playing Hide and Seek'.
5"x7" dry plate contact print (Ilford Multigrade paper).
Full instructions for making dry plates are in the book, "The Light Farm, Volume 1, The Basics," available to buy or read for free in Blurb preview. See the link at the top, right-hand side of the home page. Also, making dry plates is covered in the Light Farm web tutorials, left-hand column, home page.
Dry Plate Photography is simply photography. The 'plate' part, of course, is the glass plate emulsion support but the 'dry' part can be confusing if you aren't up on the minutia of the history of photography.
Before dry there was wet, as in wet plate photography. Collodion syrup carries the photosensitive bits, not gelatin. And, indeed, the plate is wet when it is exposed. There are enough modern wet plate practitioners that it's easy to find information. It's a fascinating process, with its own distinctive beauty. And it's dangerous, difficult, and capricious. Dry plate photography reduced all those aspects for the photographers of the day.
If the history of photography is about anything, it is about banishing one, or all, of "dangerous, difficult, and capricious". Defenders of any next-generation iteration of our craft have always been fond of claiming the newest technology is about photographic quality, but quality is subjective — the most personal of all artistic decisions. We are driven to make what we consider beautiful and we are drawn to the best technology to realize our vision.
Dry plate is one expression of beauty and one technology — as revolutionary in its day as digital is in ours. A nice bonus was/is that it is hardly dangerous, difficult or capricious. That's not to say there isn't a learning curve!