Sentence:  They now began by a change of diet and other precautions to prepare themselves to encounter the <WSD>torrefaction</WSD> of a tropical climate, and in somewhat more than a fortnight arrived in Carlisle Bay in the island of Barbadoes, which was appointed the general rendezvous of the expedition. 
Meaning of the word marked with <WSD> tags:  The act or process of subjecting something to heat or to highly acidic substances.