A method of development invented by William Fox Talbot in the 1830s, the foundation was plain table salt. The images are reddish brown to brownish violet tones with a matte finish. Salt paper copies are sometimes called kalotypier, kalotypi is actually a later development of William H. Fox Talbot's developing process.
The method was that a paper was prepared with saline made from ordinary table salt. Then brushed one side with silver nitrate solution, it creates a hardy surface of silver chloride that is photosensitive. The paper darkens when exposed to light and when the image appears clearly enough, the process is stopped with a strong saline solution. Gradually, sodium thiosulphate was used which was better at keeping the colors stable.
It is difficult to elicit on the saline paper , the chemicals are sensitive and unstable so it is easy to fail.
Silver nitrate toxic so it is necessary to be careful, it reacts easily with dirt, dust or rust from the water pipes and then the pictures become spotted and spotted, therefore distilled water is needed for the solutions. Iron destroys the process. It is also important that the water maintains the right temperature so as not to affect the process.
I realize that one has to read on about the whole process before one tries this. Modern paper contains a lot of chemicals that in turn affect the chemicals in the development.