William Brownrigg writing in 1748, in his ‘Book of Common Salt’, shows a wood-cut of one of these salt-making pans. The change to iron (from lead) coincided with a change from wood to coal for the purpose of heating the brine. Gradually, the pans increased in size.
In his 1748 publication, 'Book of Common Salt', William Brownrigg illustrated a wood-cut of one of these salt-making vessels. At the same time, the material used for the pans changed from lead to iron, and the heating process switched from wood to coal. As a result, the size of the pans gradually increased.