FORMATION OF THE DIAMOND               131
	have the constituents of the diamond in a form admitting of crystallization, and the subsequent absorption of its oxygen by the iron always present in its containing walls during long inter­mittent periods of volcanic inactivity. There are proofs in the Kimberley mine that such alternating periods of activity and repose have occurred at long intervals, as shown by the four or
	five distinct and separate layers of diamonds lining its walls, of varying size and quality, known and recognizable by diamond buyers." In this presentation, which Dr. Atherstone seemingly re­garded as conclusive, there is a lack of the clear, logical reason­ing which in other discussions has distinguished his views. He dogmatically puts the carbonic acid gas evolved from the car-