Sentence:  Exploring, I found another short gallery running transversely to the first. This appeared to be devoted to minerals, and the sight of a block of sulphur set my mind running on gunpowder. But I could find no saltpeter; indeed no nitrates of any kind. Doubtless they had <WSD>deliquesced</WSD> ages ago. Yet the sulphur hung in my mind and set up a train of thinking. As for the rest of the contents of that place, though on the whole they were the best preserved of all I saw—I had little interest. I am no specialist in mineralogy, and I soon went on down a very ruinous aisle running parallel to the first hall I had entered. 
Meaning of the word marked with <WSD> tags:  To melt and disappear.