Photographic Notes quoted James Ross in 1857:
"My attention was first drawn to this subject
from the circumstance of the very first calotype I ever had in my hand
vanishing from my sight while admiring it. It had been merely washed,
probably in common salt.
This took place some fourteen or fifteen years
ago, when in conjunction with Mr. Bishop, a very able chemist, I made my
first experiments in the art.
We soon, or rather I should say my fellow
worker soon, mastered the negatives completely…."
Notes, vol. 2, 1 October 1857, pp. 361-364.