Consul-General Guenther of Frankfort, writes concerning the most recent efforts for the production of artificial diamonds, as follows:
Crystallized carbon, as chemistry has taught for a long time, occurs in nature in two entirely different forms - as diamond and as graphite. Anyone who can afford to do so can burn a diamond in oxygen and become convinced that nothing remains except pure carbonic acid. The only compensation, except this knowledge, for the costliness of the experiment is the brilliant light colors under which the diamond, so to speak, gives up its life.
When the nature of the diamond was first discovered many chemists were full of hope that they would succeed in producing artificial diamonds of considerable size from carbon. This, however, has not been accomplished thus far, and today it is assumed that the formation of large diamons, principally found in South Africa has been under conditions which have not been possible to produce in the laboratory. From time to time artificial diamonds have been made from carbon under great pressure, but these experiments were always more expensive than the value of the diamonds obtained and, besides, were very dangerous. In one instance the laboratory of the experimenter was completely destroyed.
The French chemist, Moissau, has shown a new method for producing artificial diamonds by the employment of molten iron as a solvent for carbon, and using the electric stove, invented by himself, for producing a degree of heat hitherto not reached. Through the intense heat of this electric stove and by sudden cooling of the molten metal, the carbon is separated in the form of very small diamond crystals. The London " Lancet " reports a further step in advance in the production of crystalized carbon through experiments of Dr. Burton of Cambridge. This scientist has proved that the diamond is a denser form of crystal than graphite, and that a lesser pressure is sufficient for producing artificial diamonds than had been employed heretofore. Doctor Burton in his experiments used a molten alloy of lead and some metallic calcium, which can also hold a small quantity of carbon in solution.
If the calcium is separated from the molten mass, some of the carbon crystallizes. The separation of calcium can, for instance, be accomplished through steam. If the introduction of steam is made during full red heat, then small graphite crystals are found in the resulting crust of lime; if the steam is introduced during a low red heat, no graphite is formed, but a number of microscopical crystals are formed, the properties of which are entirely identical with those of natural diamonds. These experiments, which may be continued, strengthen the belief that it may be possible some day to produce in the laboratory of the chemist diamonds of sufficient size and perfection to compete with natural diamonds.
These experiments furnish a new theory with reference to the probable origin of the diamonds, which may not have been under an excessively high temperature, but from a poculiar crystallization from a yet unknown solvent, perhaps under high pressure. The artificial diamonds obtained by Dr. Burton are pronounced to be the finest so far observed, because they possess an unusually high power of refraction.
Sir William Brookes, in a lecture recently delivered at Kimberley before the British Association, called attention to a peculiarity of diamonds, namely, that they are especially transparent for X-rays, while imitation diamonds hardly let these rays pass through them, and he declared that this furnished an excellent means of distinguishing genuine diamonds from imitation diamonds.