What curious thing burns Buck's tongue while on the Narwhal?

In "The Call of the Wild," the substance that burns Buck's tongue while on the Narwhal is salt. This moment highlights Buck's sensory experiences as he navigates his new environment, which is harsh and unfamiliar to him. Buck encounters salt when he licks the snow that has been contaminated with the remains of a dead animal, illustrating the harsh realities of survival in the wild. The sensation of the salt on his tongue contrasts with his previous experiences, showcasing the stark differences in his life in the wilderness compared to his past. This event emphasizes Buck's adaptation to the challenges and strange occurrences of his new life, reinforcing the theme of survival and the instinctual pull of nature that characterizes his journey.