As there is gas in the room, he couldn't have wanted the candle to undress by.

He used stearine candles, too; not the common paraffin variety.

I wonder why he went to that expense." "Perhaps the smell of the paraffin candle spoiled the aroma of the opium," I suggested; to which Thorndyke made no reply but continued his inspection of the room, pulling out the drawer of the washstand--which contained a single, worn-out nail-brush--and even picking up and examining the dry and cracked cake of soap in the dish.
"He seems to have had a fair amount of clothing," said Thorndyke, who was now going through the chest of drawers, "though, by the look of it, he didn't change very often, and the shirts have a rather yellow and faded appearance.

I wonder how he managed about his washing.

Why, here are a couple of pairs of boots in the drawer with his clothes! And here is his stock of candles.