Of course, as the hot tube suddenly chilled, there was a great shrinking in the walls of the furnace, so that the already compressed carbon vapor was subjected to a still greater pressure which possibly liquified it. Of that, however, we cannot speak definitely. This, however, can safely be asserted, that when the tube was broken open a confused mass of small crystals was found inside, some of which, on examination with the microscope, were found to consist of small crystals of two forms of diamonds, namely, the black diamond, or carbonado, and the regular crystallized diamond. Moissan made a great number of experiments for producing diamonds in this way, and succeeded in forming some very beautiful, though microscopic, diamonds. What may be said to characterize especially Moissan's experiments was the comparatively great number of diamonds, so small as to be scarcely distinguishable under the microscope. The high temperature to which the materials inside the tube were exposed resulted in the production of numerous minute crystals of different minerals. In order to get rid of as many of these as possible Moissan adopted the plan of subjecting the material to the action of powerful solvents, such as sulphuric acid, aqua regia, or a mixture of sulphuric and nitric acid, and hydrofluoric acid. These acids destroyed most of the minute crystals of other minerals, but left the minute crystals of diamonds unaffected. Now it will be observed that the theory proposed by Prof. Carvill Lewis as to the probable origin of the diamonds of the Kimberly mines bears a wonderfully close resemblance to the method adopted by Moissan for the production of artificial diamonds, since it supposes the diamonds to have been formed by the sudden cooling or chilling within the pipe of various molten materials brought up from great depths by the volcanic forces. If this be true, then besides the comparatively large crystallized and perfect diamonds found in the blue ground of the Kimberly mines, there should also be found large quantities of microscopic diamonds, just as are found in Moissan's electric furnaces, in which he produced artificial diamonds. Moissan, considering this, obtained a specimen of the blue ground from the Kimberly diamond pipe and on subjecting it to the action of the different solvents before named, found in the mass that was left undissolved a great number of microscopic diamonds. It would seem, therefore, that there is no reasonable doubt but that the Kimberly diamond fields had their diamonds produced by the sudden chilling in the volcanic pipes of molten materials brought from great depths by the force of volcanic eruption. CHAPTER XXXVII THE FABLED CONTINENT OF ATLANTIS Besides the sudden changes of level that frequently occur during earthquake shocks there are gradual changes of level that take place very slowly throughout long periods of time.