Oh....Arthur's expecting smoke and crackling or whatever happens when good linen is introduced to lava. Much to his surprise, that is not what he's presented with.

"Ah. Well. It will dry."

Better to be wet than go up in flames. Well now! How do you like that? It's not a trick after all. Arthur can hardly believe it, but the proof is right there in his sodden handkerchief.

"I suppose it's all tickety boo, then. Lava baths! The wonders truly never cease, do they?" But still he takes another moment watching the magma, as though for some delayed reaction. Every fiber in his being is telling him this is all wrong. But he can't just not bathe. He went through that for weeks, never again. So. With lingering trepidation, he begins toeing off his boots and unbuckling his belt.