Ch. 14: Synthetic Man Made Diamonds

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	THE BOOK OF DIAMONDS In the mines of South Africa, diamonds are found in a hard blue ground which may have had some part in forming diamonds in nature. With this fact in mind, some blue ground was obtained from South Africa and used in an experiment as a solvent for carbon. This blue ground worked in much the same way as iron until it was treated with acid in an attempt to dissolve it. The mass then became as hard as concrete and nothing more could be done with it. Recently, other substances have been substituted for sugar carbon, especially pure gum arabic—a form of starch —since this has a larger number of carbon atoms per molecule. Coal, wood-charcoal, coke, petroleum carbon, and other forms of carbon were used, but the most successful has been gum arabic. In most cases the atmosphere of the furnace during the heating was one atmosphere of the ordinary air. In a number of cases hydrogen was used as atmosphere during the experiment. A steady flow of hydrogen was passed into the furnace before the electric current was turned on and continued until the mass was completely fused. The hydrogen was generated a long distance from the furnace and dried by passing through calcium chloride before passing into the furnace. Some diamonds are formed in such an atmosphere but none larger than with ordinary atmosphere. In several experiments a small natural diamond was used with the hope that it might serve as a nucleus for a larger diamond. In only one case, however, did we obtain a small diamond. But on that occasion we had not weighed the ^J34

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