Is there any evidence of significant mobilization of salt in Campbell's Chamber after 1837 ....
Yes. This is from "Narrative of a Voyage to Madeira, Teneriffe and ..." by W.R. Wilde 1844
"The stones forming the floor of each of these apartments roof the one below it; their upper surface is slightly convex; and the whole of them are coated with a remarkable incrustation of a shining white, curly, and crystaline substance, not unlike the moss called ursnea barbata, which I before described as covering some of the trees at Maira. It is found in little bunches on the roof, more abundantly in the upper than the lower chambers, and as it has not, that I am aware of, been yet accurately described, and is generally suposed to be nitrate of potash, or saltpetre, I submitted it to the chemical analysis of my friend Professor Kane, and he found it to be common salt (chloride of sodium), and states that "its occurrence in this form is of considerable interest, as it illustrates the manner in which some species of the alum family assume the curious fibrous and contorted figure of these specimens." A question of exceeding interest here presents itself-how did it get into and crystalize on the sides of those chambers?"