The third archway led to a very sizeable chamber entirely lined with shelves and having in the centre a table bearing two lamps. These lamps Willett lighted, and in their brilliant glow studied the endless shelving which surrounded him. Some of the upper levels were wholly vacant, but most of the space was filled with small odd-looking leaden jars of two general types; one tall and without handles like a Grecian lekythos or oil-jug, and the other with a single handle and proportioned like a Phaleron jug. All had metal stoppers, and were covered with peculiar-looking symbols moulded in low relief. In a moment the doctor noticed that these jugs were classified with great rigidity; all the lekythoi being on one side of the room with a large wooden sign reading "Custodes" above them, and all the Phalerons on the other, correspondingly labelled with a sign reading "Materia". Each of the jars or jugs, except some on the upper shelves that turned out to be vacant, bore a cardboard tag with a number apparently referring to a catalogue; and Willett resolved to look for the latter presently. For the moment, however, he was more interested in the nature of the array as a whole; and experimentally opened several of the lekythoi and Phalerons at random with a view to a rough generalisation. The result was invariable. Both types of jar contained a small quantity of a single kind of substance; a fine dusty powder of very light weight and of many shades of dull neutral colour. To the colours which formed the only point of variation there was no apparent method of disposal; and no distinction between what occurred in the lekythoi and what occurred in the Phalerons. A bluish-grey powder might be by the side of a pinkish-white one, and any one in a Phaleron might have its exact counterpart in a lekythos. The most individual feature about the powders was their non-adhesiveness. Willett would pour one into his hand, and upon returning it to its jug would find that no residue whatever remained on his palm.