October 12, 1905] 



NA TURE 



593 



Mrs. Bryant, in the course of an address on " Ideals 

 of Study " at the London School of Medicine for Women, 

 said that an ideal of study was most usefully conceived, not 

 as a scheme of learning to be achieved, but rather in its 

 psychological essence as growing out of the primitive 

 intellectual interests of human beings. Interest in know- 

 ledge for its own sake — the theoretic interest — was to be 

 found more or less in every healthy normal person. 

 .\ccording to brain type, habit, association, and other 

 circumstances, its bent towards one or another branch of 

 knowledge varied in individuals. 



It was suggested that more should be done in elementary 

 and secondary education (i) to develop the practical interest 

 in relation to all the every-day problems arising naturally 

 in the environment: and (2) to train it to a high ideal of 

 the science and skill involved in their solution. The neglect 

 of the practical interest in the practically minded was not 

 only loss of good material for practical efficiency ; it was 

 also the loss of opportunity for the cultivation of the scien- 

 tific interest. To inquire how a thing was made led to 

 inquiry as to its causation, and at that point the youth 

 or child becomes athirst for science. 



.'\t the London School of Tropical Medicine. Dr. George 

 Nuttall, F.R.S., delivered an address on " Scientific Re- 

 search in Medicine," in the course of which he pointed 

 out the great benefits to mankind which have followed 

 such discoveries as those of the causes and prevention of 

 yellow fever and malaria, and that the majority of such 

 discoveries have been made by those engaged in research 

 and in the realms of pure science, and rarely by those 

 guided by principles of direct and immediate utility. He 

 urged the necessity for the endowment of research, par- 

 ticularly in experimental medicine, and finally proceeded 

 to review recent work in protozoologv and parasitology. 



At the .School of Pharmacy. Pharmaceutical Society of 

 Great Britain, Sir Boverton Redwood delivered the address 

 on " General Study and Specialism," and at the Royal 

 \'eterinary College Mr. Hunting discussed the career of 

 members of the veterinary profession. 



D7.4MOA^DS.' 

 "p ROM the earliest times the diamond has fascinated 

 mankind. It has been a perennial puzzle — one of the 

 " riddles of the painful earth." It is recorded in " Sprat's 

 History of the Royal Society " (1667) that among the 

 questions sent by order of the society to Sir Philiberto 

 \'ernatti, resident in Batavia, was one inquiring 

 " Whether Diamonds grow again after three or four years 

 in the same places where they have been digged out? " 

 The answer sent back was " Never, Or at least as the 

 memory of man can attain to." 



Of late years the subject has fascinated many men of 

 science. The development of electricity, with the introduc- 

 tion of the electric furnace, has facilitated research, and I 

 am justified in saying that if the diamond problem is not 

 actually solved, there is every probability it shortly will 

 be solved. 



South Africa, as I will show in detail, is the favourite 

 haunt of diamonds on this planet : it ranks with .Australia 

 and California as one of the three great gold-yielding 

 regions. But the wealth of South Africa is not limited 

 to gold and diamonds. It is also the illimitable home of 

 coal — " the black diamond " of the universe. The 

 province of Natal alone contains more coal than Britain 

 ever owned before a single bucket had been raised ; and 

 the coal beds extend into the Orange River Colony. 

 \'aluable iron ores exist also in large quantities. 



The Pipes at Kimberley. 

 The five diamond mines are all contained in a precious 

 circle 33 miles in diameter. They are irregular shaped 

 round or oval pipes, extending vertically downwards to 

 unknown depths, retaining about the same diameter 

 throughout. They are considered to be volcanic necks, 

 filled from below with a heterogeneous mixture of frag- 

 ments of surroimding rocks, and of older rocks such as 

 granite, mingled and cemented with a bluish coloured hard 



' 1 Abrldjed frnm a lecture HeliverH before the ririiish Associnlion at 

 Kimberley on September 5 by Sir William Crookes, F.P.S. 



NO. 1876, VOL. 72] 



clayey mass, in which famous blue clay the imbedded 

 diamonds are hidden. 



How the great pipes were originally formed is hard to 

 say. They were certainly not burst through in the ordinary 

 manner of volcanic eruption, since the surrounding and 

 enclosing walls show no signs of igneous action, and are 

 not shattered or broken up even when touching the " blue 

 ground." It is pretty certain these pipes were filled from 

 below after they were pierced, and the diamonds were 

 formed at some previous time and mixed with a mud 

 volcano, together with all kinds of df?bris eroded from the 

 rocks through which it erupted, forming a geological 

 " plum pudding." The direction of flow is seen in the 

 upturned edges of some of the strata of shale in the walls, 

 although I was unable to see any upturning in most parts 

 of the walls of the De Beers mine at great depths. 



The breccia filling the mines, usually called " blue 

 ground," is a collection of fragments of shale, and of 

 various eruptive rocks, boulders, and crystals of many 

 kinds of minerals. Indeed, a more wildly heterogeneous 

 mixture can hardly be found anywhere else on this globe. 

 The Kimberley mines for the first 70 feet or 80 feet are 

 filled with so-called "yellow ground," and below that 

 with " blue ground." This superposed yellow on blue 

 is common to all the mines. The blue is the aboriginal 

 ground, and owes its colour chiefly to the presence of 

 lower oxides of iron. When atmospheric influences have 

 access to the iron it becomes peroxidised, and the grouiid 

 assumes a yellow colour. The thickness of yellow earth in 

 the mines is therefore a measure of the depth of penetration 

 of air and moisture. The colour does not affect the yield 

 of diamonds. The ground mass is soapy to the toiich, 

 and friable, especially after exposure to weather. Besides 

 diamonds, more than eighty species of minerals have been 

 recognised in the blue ground, the most common being 

 magnetite, ilmenite, garnet, bright green ferriferous 

 enstatite (bronzite), a hornblendic mineral closely re- 

 sembling smaragdite, calc-spar, vermiculite, diallage, 

 jefl'revsite, mica, kyanite, augite, peridot, iron pyrites, 

 woUastonite, vaalite, zircon, chrome iron, rutile, corun- 

 dum, apatite, olivine, sahlite, chromite, pseudobrookite, 

 perofskite, biotite, and quartz. 



The blue ground does not show any signs of igneous 

 action ; the fragments in the breccia are not fused at the 

 edges. The eruptive force was probably steam or water- 

 gas, acting under great pressure but at no high 

 temperature. 



There are many such pipes in the immediate neighbour- 

 hood of Kimberley. It may be that each volcanic pipe 

 is the vent for its own special laboratory — a laboratory 

 buried at vastly greater depths than we have yet reached 

 — where the temperature is comparable with that of the 

 electric furnace, where the pressure is fiercer than in our 

 puny laboratories and the melting point higher, where 

 no oxygen is present, and where masses of liquid carbon 

 have taken centuries, perhaps thousands of years, to cool 

 to the solidifying point. The chemist arduously manu- 

 factures infinitesimal diamonds, valueless as ornaiinental 

 gems ; but nature, with unlimited temperature, incon- 

 ceivable pressure, and gigantic material, to say nothing 

 of measureless time and appalling energy, produces without 

 stint the dazzling, radiant, beautiful, coveted crystals I 

 am enabled to show you to-night. 



This hypothesis of the origin of diamonds is in many 

 ways corroborated. 



the ash left after burning a diamond invariably con- 

 tains iron as its chief constituent ; and the most common 

 colours of diamonds, when not perfectly pellucid, show 

 various shades of brown and yellow, from the palest " off 

 colour " to almost black. TheV are also green, blue, pink, 

 yellow, and orange. These variations give support to the 

 theory advanced bv Moissan that the diamond has separated 

 from molten iron— a theory of which I shaU say more 

 presently — and also explain how it happens that stones 

 from different mines, and even from difl'erent parts of the 

 same mine, differ from each other. Further confirmation 

 is given by the fact that the country round Kimberley is 

 remarkable for its ferruginous character, and iron- 

 saturated soil is popularly regarded as one of the indi- 

 cations of the near presence of diamonds. Along with 

 carbon, molten iron dissolves other bodies which possess 



