232 DIAMONDS. 



commenced by steam would be continued by the otber gases, and it 

 would be no difficult task for pipes, large as any found in South Africa, 

 to be scored out in this manner. Sir Andrew Koble has shown that 

 when the screw stopper of his steel cylinders in which gunpowder 

 explodes under pressure is not absolutely perfect, gas finds its way out 

 with a rush so overpowering as to score a wide channel in the metal. 

 Some of these stoppers and vents are on the table. To illustrate ray 

 argument Sir Andrew Noble has been kind enough to try a special 

 experiment. Through a cylinder of granite is drilled a hole 0.2 inch 

 diameter, the size of a small vent. This is made the stopper of an 

 explosion chamber, in which a quantity of cordite is fired, the gases 

 escaping through the granite vent. The pressure is about 1,500 atmos- 

 pheres, and the whole time of escape is less than half a second. Notice 

 the erosion produced by the escaping gases and by the heat of friction, 

 which have scored out a channel over half an inch diameter and melted 

 the granite along their course. If steel and granite are thus vulnerable 

 at comparatively moderate gaseous pressure, is it not easy to imagine 

 the destructive upburst of hydrogen and water-gas grooving for itself 

 a channel in the diabase and quartzite, tearing fragments from resist- 

 ing rocks, covering the country with debris, and finally, at the subsid- 

 ence of the great rush, filling the self-made pipe with *a water borne 

 magma in which rocks, minerals, iron oxide, shale, petroleum, and 

 diamonds are churned together in a veritable witch's cauldron! As 

 the heat abated the water vapor would gradually give place to hot 

 water, which, forced through the magma, would change some of the 

 mineral fragments into the now existing forms. 



Each outbreak would form a dome shaped hill, but the eroding 

 agency of water and ice would plane these eminences until all traces 

 of the original pipes were lost. 



Actions, such as I have described, need not have taken j)lace simul- 

 taneously. As there must have been many molten masses of iron with 

 variable contents of carbon, different kinds of coloring matter, solidi- 

 fying with varying degrees of rapidity, and coming in contact with 

 water at intervals throughout long periods of geological time^so must 

 there have been many outbursts and upheavals, giving rise to pipes 

 containing diamonds. And these diamonds, by sparseness of distri- 

 bution, crystalline character, difference of tint, purity of color, vary- 

 ing hardness, brittleness, and state of tension, would have impressed 

 upon them, engraved by natural forces, the story of their origin — a 

 story which future generations of scientific men may be able to inter- 

 pret with greater iDrecision than we can to day. 



Who knows but that at unknown depths in the earth's metallic core 

 beneath the present pipes there are still masses of iron not yet disin- 

 tegrated and oxidized by aqueous vapor — masses containing diamonds, 

 unbroken, and in greater profusion than they exist in the present blue 

 ground, inasmuch as they are inclosed in the matrix itself, undiluted by 



