,,transcriber',s ,,note ,italic text is denoted by underscores4 ,footnote anchors are denoted by number1 and the footnotes have been placed at the end of the book4 ,a subscript is denoted by x1 for example ,c#b4 ,basic fractions are displayed as etc2 other fractions are shown in the form a_/b1 for example #a_/add or #e_/ab4 ,some minor changes to the text are noted at the end of the book4 ,,harper',s ,,library of ,,living ,,thought ,illustration3 7publisher colophon7 ,illustration3 ,,diamonds ,,by ,,sir ,,william ,,crookes ,,harper ,,brothers ,,london ,,new ,,york ,illustration3 ,,the ,,cullinan ,,diamond4 ,from a photograph by the ,author4 7,see pages #gf-gi47 ,frontispiece4 ,,diamonds ,,by ,,sir ,,william ,,crookes ,,ll4,d41 ,d4,sc41 ,f4,r4,s4 ,foreign ,sec4 ,r4,s41 ,hon4 ,,ll4,d4 7,birmingham71 ,hon4 ,sc4,d4 7,camb4 and ,dubl471 ,hon4 ,d4,sc4 7,oxon4 and ,cape of ,good ,hope72 ,past ,pres4 ,chem4 ,soc41 ,brit4 ,assoc41 ,inst4 ,elect4 ,eng41 ,soc4 ,psych4 ,res42 ,hon4 ,mem4 ,roy4 ,phil4 ,soc4 ,glasgow1 ,roy4 ,soc4 ,n4,s4,w41 ,pharm4 ,soc41 ,chem4 ,metall4 and ,mining ,soc4 of ,south ,africa1 ,amer4 ,chem4 ,soc41 ,amer4 ,philos4 ,soc41 ,roy4 ,soc4 ,sci4 ,upsala1 ,deutsch4 ,chem4 ,gesell4 ,berlin1 ,psychol4 ,soc4 ,paris1 8,antonio ,alzate0 ,sci4 ,soc4 ,mexico4 ,sci4 ,soc4 ,bucharest1 ,reg4 ,accad4 ,zelanti1 ,aci ,reale2 ,corresp4 ,inst4 de ,france 7,acad4 ,sci471 ,corresp4 ,mem4 ,bataafsch ,genoots4 ,rotterdam1 ,soc4 d',encouragement pour l',indust4 ,paris1 ,for4 ,mem4 ,accad4 ,lincei ,rome4 ,,with #bd ,,illustrations ,,london ,,and ,,new ,,york ,,harper ,,brothers #de ,,albemarle ,,street1 ,w4 #aiji ,,to ,,my ,,wife ,,my ,,companion ,,and ,,friend ,,of ,,fifty-,,four ,,years4 ,,to ,,her ,,judgment ,,and ,,advice ,i ,,owe ,,more ,,than ,i ,,can ,,ever ,,repay ,,and ,,to ,,her ,i ,,dedicate ,,this ,,book4 ,,preface ,the following pages are based on personal observations during two visits to ,kimberley1 in #ahif and #aije1 and on personal researches on the formation and artificial production of diamonds4 ,in #ahif ,i spent nearly a month at ,kimberley1 when ,mr4 ,gardner ,f4 ,williams1 the ,general ,manager of the ,de ,beers ,consolidated ,mines1 and the managers of neighbouring mines1 did their utmost to aid in my zealous quest for reliable information4 ,they gave me free access to all workings above and below ground1 allowed me to examine at leisure their stock and to take extracts from their books4 ,i had exceptional opportunities of studying the geology of the ,diamond and of noting the strange cataclysmal facts connected with the birth1 growth1 and physics of the lustrous stones4 ,in #aije with my wife ,i returned to ,kimberley4 ,we were members of the ,british ,association which held its meeting that year in ,south ,africa4 ,i was asked to give one of the ,association lectures at ,kimberley and it was natural for me to discourse 8,on ,diamonds40 ,during our stay we were the guests of ,mr4 ,gardner ,williams4 ,returning to ,england after the visit of #ahif1 ,i gave two lectures on ,diamonds at the ,imperial ,institute and one at the ,royal ,institution4 ,these lectures1 and the lecture delivered at ,kimberley1 in #aije--;hitherto only privately distributed--form the basis of the present volume4 ,on each visit ,i took abundant photographs1 many of which ,i now reproduce4 ,a few are copied from plans lent by ,mr4 ,gardner ,williams and one or two are from photographs purchased at ,kimberley4 ,in obtaining statistical information of the ,diamond industry1 ,i owe much to the ,annual ,reports of the ,de ,beers ,company4 ,i have also quoted freely from ,reunart's valuable book on ,diamonds and ,gold in ,south ,africa2 and ,i render my acknowledgments to the authors of the following papers and memoirs4 ,on a ,visit to the ,diamond ,fields of ,south ,africa1 with ,notices of ,geological ,phenomena by the ,wayside4 ,by ,john ,paterson1 ,esq41 ,m4,a4 ,on the ,mode of ,occurrence of ,diamonds in ,south ,africa4 ,by ,e4 ,j4 ,dunn4 ,on the ,origin and ,present ,position of the ,diamonds of ,south ,africa4 ,by ,g4 ,g4 ,cooper1 ,esq41 of ,graaf ,reinet4 ,on the ,character of the ,diamantiferous ,rock of ,south ,africa4 ,by ,prof4 ,n4 ,storey ,maskelyne1 ,f4,r4,s41 ,keeper1 and ,dr4 ,w4 ,flight1 ,assistant in the ,mineral ,department1 ,british ,museum4 ,further ,notes on the ,diamond ,fields of ,south ,africa4 ,by ,e4 ,j4 ,dunn4 ,notes on the ,diamond ,fields of ,south ,africa1 #ahhj4 ,by ,e4 ,j4 ,dunn4 ,analogies between the ,diamond ,deposits in ,south ,africa and those in ,meteorites4 ,by ,m4 ,daubre4 ,notes on the ,diamond-bearing ,rock of ,kimberley1 ,south ,africa4 ,by ,sir ,j4 ,b4 ,stone1 ,prof4 ,t4 ,g4 ,bonney1 and ,miss ,raisin4 ,notes on the ,diamond ,rock of ,south ,africa4 ,by ,w4 ,h4 ,hudleston4 ,the ,parent ,rock of the ,diamond in ,south ,africa4 ,by the ,reverend ,professor ,t4 ,g4 ,bonney4 ,the ,presidential ,address1 by ,grove ,carl ,gilbert1 to the ,geological ,society of ,washington1 on ,the ,origin of ,hypotheses4 ,illustrated by the ,discussion of a ,topographical ,problem4 #ahif4 ,le ,four ,electrique4 ,by ,henri ,moissan4 #ahig4 ,the ,diamond ,mines of ,south ,africa4 ,by ,mr4 ,gardner ,f4 ,williams4 7,in this publication the story of the rise and development of the industry is exhaustively narrated47 ,british ,association1 ,south ,african ,meeting1 #ahif1 ,kimberley ,handbook4 ,the ,meteor ,crater of ,canyon ,diablo1 ,arizona2 its ,history1 ,origin1 and ,associated ,meteoric ,irons4 ,by ,george ,p4 ,merrill4 #aijh4 ,in the present volume ,i have tried to give some idea of the underground wonders of the ,kimberley mines4 ,i have pictured the strenuous toil of the men who bring to the surface the buried treasures1 and ,i have given some idea of the skill and ingenuity with which their labours are controlled4 ,i have done my best to explain the fiery origin of the ,diamond1 and to describe the glowing1 molten1 subterranean furnaces where they first begin mysteriously to take shape4 ,i have shown that a diamond is the outcome of a series of ,titanic earth convulsions1 and that these precious gems undergo cycles of fiery1 strange1 and potent vicissitudes before they can blaze on a ring or a tiara4 ,i am glad to have paid these two visits to ,south ,africa4 ,i always recall with interest the dusky smiling natives at work and at play4 ,i am glad to have seen that ,arabian ,nights vision1 the strong-room of the ,de ,beers ,company4 ,above all1 ,i have vividly graven on my heart the friendly welcome1 and the innumerable acts of kindness shown us by our able1 energetic1 and enterprising ,colonial fellow-countrymen4 ,w4 ,c4 ,,contents ,,chapter ,,page ,i4 ,,preliminary #a ,,ii4 ,,kimberley ,,and ,,its ,,diamond ,,mines #ad ,,iii4 ,,kimberley ,,mines ,,at ,,the ,,present ,,day #cd ,,iv4 ,,collecting ,,the ,,gems #ee ,v4 ,,the ,,diamond ,,office #gc ,,vi4 ,,noteworthy ,,diamonds #gf ,,vii4 ,,boart1 ,,carbonado1 ,,and ,,graphite #ha ,,viii4 ,,physical ,,and ,,chemical ,,properties ,,of ,,the ,,diamond #hi ,,ix4 ,,genesis ,,of ,,the ,,diamond #aae ,x4 ,,the ,,natural ,,formation ,,of ,,the ,,diamond #abg ,,xi4 ,,meteoric ,,diamonds #acd ,,index #ada ,,list ,,of ,,plates ,the ,cullinan ,diamond1 from a photograph by the ,author 7see pp4 #gf-gi7 ,frontispiece ,,fig4 ,,facing ,,page #a4 ,river ,washings at ,klipdam #aj #b4 ,plan of the ,kimberley ,diamond ,mines #aj #c4 ,kimberley ,mine4 ,the 8,pipe0 #ah #d4 ,section of ,kimberley ,mine #ah #e4 ,wesselton ,diamond ,mine4 ,open ,workings #cd #f4 ,de ,beers ,compound #dj #g4 ,de ,beers ,mine4 ,underground ,workings #dj #h4 ,de ,beers ,washing and ,concentrating ,machinery #dh #i4 ,sorting ,concentrates for ,diamonds4 ,de ,beers #ed #aj4 ,de ,beers ,diamond ,office4 #be1jjj carats #gb #aa4 ,de ,beers ,diamond ,office4 ,the ,valuators' ,table #gb #ab4 ,a group of large ,diamond ,crystals #gf #ac4 ,some ,historic ,diamonds #hj #ad4 ,crystalline forms of native ,diamonds #hf #ae4 ,triangular ,markings on natural face of a ,diamond ,crystal #hh #af4 ,triangular ,markings artificially produced on a ,diamond ,crystal #hh #ag4 ,diamond-cut ,glass and ,shavings #ih #ah4 ,diamonds in ,rntgen ,rays4 ,a4 ,black ,diamond in gold frame4 ,b4 ,pink ,delhi ,diamond4 ,c4 ,paste ,imitation of ,b4 #ih #ai4 ,curve of ,vapour ,pressure of ,carbon page #aac #bj4 ,moissan's ,electric ,furnace #aaf #ba4 ,artificial ,diamond made by the ,author from molten iron #abj #bb4 ,moissan's ,artificial ,diamonds #abj #bc4 ,diamonds from ,canyon ,diablo ,meteorite #ach ,,diamonds ,,chapter ,i ,,preliminary ,from the earliest times the diamond has fascinated mankind4 ,it has been a perennial puzzle--one of the 8riddles of the painful earth40 ,it is recorded in ,sprat's ,history of the ,royal ,society 7#affg7 that among the questions sent by order of the ,society to ,sir ,philiberto ,vernatti1 ,resident in ,batavia1 was one inquiring 8,whether ,diamonds grow again after three or four years in the same places where they have been digged out80 ,the answer sent back was1 8,never1 or at least as the memory of man can attain to40 ,in a lecture 8,on ,diamonds10 fifty years ago1#a ,professor ,maskelyne said1 8,the diamond is a substance which transcends all others in certain properties to which it is indebted for its usefulness in the arts and its beauty as an ornament4 ,thus1 on the one hand1 it is the hardest substance found in nature or fashioned by art4 ,its reflecting power and refractive energy1 on the other hand1 exceed those of all other colourless bodies1 while it yields to none in the perfection of its pellucidity40 ,he was constrained to add1 8,the formation of the diamond is an unsolved problem40 ,diamonds are found in widely separated parts of the globe4 ,in the ,united ,states they have been found in ,arkansas1 where the work of testing the deposits is now going on steadily and quietly4 ,the general geology and petrography of the area and the weathering of the peridotite are described in a paper read before the ,american ,institute of ,mining ,engineers by ,messrs4 ,kunz and ,washington4 ,in tests made with a diamond drill the peridotite was proved to depths of #bjj feet4 ,the green and yellow grounds underlying the layer of black1 sticky soil are found to extend down #dj feet in places1 and are estimated to average #bj feet in depth over the area4 ,the outcrop of the peridotite is estimated to cover about #dj acres1 and may be larger4 ,some #edj diamonds have been found1 with an aggregate of #bjj carats4 ,the largest stone weighs about #fe carats1 though the average size compares favourably with the general run of most of the ,south ,african mines4 ,there is a large proportion of white stones1 many of which are free from flaws and are very brilliant4 ,the genuineness of the occurrence of diamonds in their matrix is again proved1 one stone having been found imbedded in the green ground at a depth of #ae feet4 ,this peridotite has the form of a volcanic pipe1 and therefore its outcrop is limited to one place4 ,in ,california authentic finds of diamonds are recorded in ,butte ,county1 especially at ,cherokee1 above ,orville4 ,these diamonds1 however1 have come from alluvial deposits and have been found generally in washing for gold4 ,as yet no authenticated discovery of diamond in its original matrix in ,california is recorded4 ,in ,brazil the diamond industry has been increasing of late years1 and the old mines in the ,diamantina country are being worked by ,american capital and by the ,american methods which have proved so successful at ,de ,beers4 ,it is estimated that the annual value of the diamonds exported from ,brazil amounts to over #hjj1jjj1 but it is impossible to arrive at accurate figures owing to the large quantities smuggled out of the country to avoid payment of the export tax4 ,british ,guiana produces a small quantity of diamonds1 mostly1 however1 of small size4 ,between ,january and ,september1 #aijg1 #aefd carats were exported4 ,indian diamonds chiefly come from the states of ,panna1 ,charkhari1 and ,ajaigarh4 ,in #aije ,india exported #cjei carats1 valued at #eafj4 ,,cape ,,colony ,it is a standing surprise to the watchful outsider how little attention is bestowed on some of our colonies4 ,for instance1 to the ,cape ,colony1 comprising vast1 varied1 and productive regions1 we have till recently manifested profound ignorance and consequent indifference4 ,when the ,cape ,colony was first incorporated with the ,empire1 it was pronounced 8a bauble1 unworthy of thanks40 ,yet before the ,suez ,canal and the ,waghorn overland route to ,india1 the ,cape1 as commanding our road to ,india1 ,australia1 and ,china1 had a special importance4 ,even now it presents an alternative route which under conceivable circumstances may be of capital moment4 ,the high grounds above ,cape ,town are rich in medicinal health-giving waters4 ,the districts where these springs occur are high-lying1 free from malaria1 and admirably adapted for the restoration of invalids4 ,it needs only some distinguished power to set the fashion1 some emperor1 prince1 or reigning beauty to take the baths and drink the waters1 and the tide of tourists would carry prosperity to ,aliwal ,north1 ,fraserburg1 ,cradock1 and ,fort ,beaufort4 ,south ,africa1 as ,i shall endeavour to show in detail1 is the most important source of diamonds on the earth1 and ranks with ,australia and ,california as one of the three great gold-yielding regions4 ,but the wealth of ,south ,africa is not only in its gold and diamonds4 ,the province of ,natal contains more coal than ,britain ever owned before a single bucket had been raised1 and the beds extend over the ,orange ,river ,colony1 whilst valuable iron ores exist also in large quantities4 ,in the year #ahif ,i spent nearly a month at ,kimberley4 ,mr4 ,gardner ,f4 ,williams1 ,general ,manager of the ,de ,beers ,consolidated ,mines1 and the ,managers of neighbouring mines1 did their utmost to assist me in my inquiries and to ply me with valuable information4 ,i had full access to all the workings1 above and below ground1 and was able to examine at leisure their stock and take extracts from their books4 ,again1 in the year #aije1 ,i paid another visit to ,kimberley as the guest of ,mr4 ,gardner ,williams on the occasion of the meeting of the ,british ,association in ,south ,africa4 ,,river ,,washings ,besides the matrix mines1 where the stones are found in pipes supposed to be of volcanic origin1 the alluvial deposits on the ,vaal ,river are of considerable importance4 ,the terraces and gravels along the ,vaal ,river for about #bjj miles have been worked for diamonds1 the deposits sometimes extending several miles on each side of the river1 and varying from a few inches to #dj or #ej feet in thickness4 ,the diamonds are found almost everywhere through the gravel deposit4 ,before describing the present mode of diamond extraction followed in the important mines1 ,i will commence with these 8,river ,washings10 where1 in their primitive simplicity1 can be seen the modes of work and the simple machinery long since discarded in the large centres of the industry4 ,the drift or so-called 8river washings0 present a very interesting phase of diamond industry4 ,the work is carried on in the primitive fashion adopted in the early days of diamond discovery1 every man working on his own little claim1 assisted by a few natives1 and employing primitive machinery 7,fig4 #a74 ,the chief centre of the ,vaal ,river washings is about #cj miles to the north-west of ,kimberley1 at a place called ,klipdam ,no4 #b4 ,there was originally a ,klipdam a few miles further1 and here the miners congregated1 but the exhaustion of their claims made them migrate to others not far off and reported to be richer4 ,here1 accordingly1 they re-erected their iron houses and called it ,klipdam ,no4 #b4 ,it is a mistake to speak of 8river washings40 ,the diamantiferous deposits are not special to the old or recent river bed1 but appear to be alluvial deposits spread over a large tract of country by the agency of water1 which at some period of time subsequent to the filling up of the volcanic pipes planed off projecting kopjes from the surface of the country and scattered the debris broadcast over the land to the north-west of ,kimberley4 ,the larger diamonds and other heavy minerals would naturally seek the lowest places1 corresponding with the river bed1 past and present4 ,the fact that no diamonds are found in the alluvial deposits near ,kimberley may perhaps be explained by supposing that the first rush was sufficiently strong to carry the debris past without deposition1 and that deposition occurred when the stream slackened speed4 ,at ,klipdam ,no4 #b the diamantiferous earth is remarkably like river gravel1 of a strong red colour--quite different from the ,kimberley blue ground--and forms a layer from #a to #h feet thick1 lying over a 8hard pan0 of amygdaloidal trap1 the melaphyre of the ,kimberley mines4 ,illustration3 ,,fig4 #a4 ,,river ,,washings ,,at ,,klipdam4 ,illustration3 ,,fig4 #b4 ,,plan ,,of ,,the ,,kimberley ,,diamond ,,mines4 ,to face p4 #aj4 ,when ,i was at ,klipdam the miners had congregated at a spot called 8,new ,rush10 where some good finds of diamonds had been reported4 ,the gravel is dug and put into a machine resembling the gold miner's dolly1 where it is rocked and stirred by rakes1 with a current of water flowing over it4 ,here all the fine stuff is washed away and a rough kind of concentration effected4 ,the residual gravel is put on a table and sorted for diamonds--an operation performed by the master4 ,at one of the claims where work was proceeding vigorously ,i asked the proprietor to let me be present at the sorting out1 as ,i should like to see river diamonds4 ,he willingly consented1 but no diamonds were to be found4 ,on my expressing regret1 he said he had not seen a diamond for a fortnight6 ,i remarked that the prospect was rather a poor one1 but he told me that a fortnight before he picked out one worth #cjj1 8and that10 he said1 8will pay for several weeks' wages of my boys40 ,this is the kind of speculative gambling that goes on at the river diggings4 ,the miner may toil fruitlessly for months1 and then come across a pocket of stones1 where they have been swept by some eddy1 by which he will net several thousands4 ,diamonds from the 8river washings0 are of all kinds1 as if contributed by every mine in the neighbourhood4 ,they are much rolled and etched1 and contain a good proportion of first-class stones2 they are of very good quality1 as if only the better and larger stones had survived the ordeal of knocking about4 ,diamonds from the drift fetch about #dj per cent more than those from ,kimberley2 taking the yield of the ,kimberley and ,de ,beers mines as worth all round1 large and small1 #bfs4 #f;d4 a carat1 those from the drift are worth #djs4 ,as a rule the better class of natives--the ,zulus1 ,matabeles1 ,basutos1 and ,bechuanas--when well treated1 are very honest and loyal to their masters4 ,an amusing instance of the devotion of a ,zulu came to my knowledge at ,klipdam4 ,he had been superintending a gang of natives on a small claim at the river washings4 ,it yielded but few stones1 and the owner--my informant--sold the claim1 handing over the plant and small staff1 our friend the ,zulu remaining to look after the business till the new owner took possession4 ,in the course of a few months the purchaser became dissatisfied with his bargain1 not a single diamond having turned up since the transfer4 ,one night the ,zulu came to his old master in a mysterious manner1 and laying a handful of diamonds on the table1 said1 8,there1 ,baas1 are your diamonds2 ,i was not going to let the new man have any of them60 ,,chapter ,,ii ,,kimberley ,,and ,,its ,,diamond ,,mines ,the famous diamond mines in the neighbourhood are ,kimberley1 ,de ,beers1 ,dutoitspan1 ,bultfontein1 and ,wesselton 7,fig4 #b74 ,they are situated in latitude #bh #dc ,south and longitude #bd #df ,east4 ,kimberley is practically in the centre of the present diamond-producing area4 ,besides these mines others of some importance of the ,orange ,river ,colony are known as ,jaggersfontein and ,koffyfontein1 ,lace1 and ,monastery1 besides two new mines1 the ,roberts-,victor and the ,voorspoed4 ,the areas of the mines are3 ,kimberley #cc acres ,de ,beers #bb acres ,dutoitspan #de acres ,bultfontein #cf acres ,in #aijg the total number of carats raised from these mines was more than two million and a half1 the sales of which realised #f1deb1eig4 ,the most important mine outside the ,kimberley group is the new ,premier ,mine1 about #bj miles ,west-,north-,west of ,pretoria1 where the famous ,cullinan diamond was found4 ,other diamond mines are the ,frank ,smith1 ,wesselton1 the ,kamfersdam1 the ,kimberley ,west1 the ,newlands1 and the ,leicester ,mine4 ,the surface of the country round ,kimberley is covered with a ferruginous red1 adhesive1 sandy soil1 which makes horse traffic very heavy4 ,below the red soil is a basalt1 much decomposed and highly ferruginous1 from #bj to #ij feet thick1 and lower still from #bjj to #bej feet of black slaty shale containing carbon and iron pyrites4 ,these are known as the ,kimberley shales2 they are very combustible1 and in a part of the ,de ,beers ,mine where they were accidentally fired they smouldered for over eighteen months4 ,then follows a bed of conglomerate about #aj feet thick1 and below the conglomerate about #djj feet of a hard1 compact rock of an olive colour1 called 8,melaphyre10 or olivine diabase4 ,below the melaphyre is a hard quartzite about #djj feet thick4 ,the strata are almost horizontal1 dipping slightly to the north2 in places they are distorted and broken through by protruding dykes of trap4 ,there is no water nearer than the ,vaal ,river1 about #ad miles away1 and formerly the miners were dependent on rain-water and a few springs and pools4 ,now1 however1 a constant and abundant supply of excellent water is served to the town1 whilst good brick houses1 with gardens and orchards1 spring up on all sides4 ,to mark the rate of progress1 ,kimberley has an excellent club and one of the best public libraries in ,south ,africa4 ,parts of the town1 affectionately called 8the camp0 by the older inhabitants1 are not beyond the galvanised iron stage1 and the general appearance is unlovely and depressing4 ,reunert reckons that over a million trees have been cut down to supply timber for the mines1 and the whole country within a radius of #ajj miles has been denuded of wood with the most injurious effects on the climate4 ,the extreme dryness of the air1 and the absence of trees to break the force of the wind and temper the heat of the sun1 probably account for the dust storms so frequent in summer4 ,the temperature in the day frequently rises to #ajj in the shade1 but in so dry a climate this is not unpleasant1 and ,i felt less oppressed by this heat than ,i did in ,london the previous ,september4 ,moreover1 in ,kimberley1 owing to the high altitude1 the nights are always cool4 ,the approach to ,kimberley is deadly dull4 ,the country is almost treeless1 and the bare veldt stretches its level length1 relieved only by distant hills on the horizon4 ,,the ,,pipes ,,or ,,craters ,the five diamond mines or craters are all contained in a circle #c miles in diameter4 ,they are irregularly shaped round or oval pipes1 extending vertically downwards to an unknown depth1 retaining about the same diameter throughout 7,fig4 #c74 ,they are said to be volcanic necks1 filled from below with a heterogeneous mixture of fragments of the surrounding rocks1 and of older rocks such as granite1 mingled and cemented with a bluish-coloured1 hard clayey mass1 in which famous blue clay the imbedded diamonds are hidden4 ,illustration3 ,,fig4 #c4 ,,kimberley ,,mine4 ,,the 8,,pipe40 ,illustration3 ,,fig4 #d4 ,,section ,,of ,,kimberley ,,mine4 ,to face p4 #ah4 ,the craters or mines are situate in depressions1 which have no outlets for the water which falls upon the neighbouring hills4 ,the watersheds of these hills drain into ponds1 called pans or vleis4 ,the water1 which accumulates in these ponds during the rainy season1 evaporates during the dry months1 only one of them holding water throughout the dry season4 ,the rocks which surround the craters are capped by red soil or calcareous tufa1 and in places by both1 the red soil covering the tufa4 ,the diamantiferous breccia filling the mines1 usually called 8blue ground10 is a collection of fragments of shale1 various eruptive rocks1 boulders1 and crystals of many kinds of minerals4 ,indeed1 a more heterogeneous mixture can hardly be found anywhere else on this globe4 ,the ground mass is of a bluish green1 soapy to the touch and friable1 especially after exposure to the weather4 ,professor ,maskelyne considers it to be a hydrated bronzite with a little serpentine4 ,the ,kimberley mine is filled for the first #gj or #hj feet with what is called 8yellow ground10 and below that with 8blue ground0 7,fig4 #d74 ,this superposed yellow on blue is common to all the mines4 ,the blue is the unaltered ground1 and owes its colour chiefly to the presence of lower oxides of iron4 ,when atmospheric influences have access to the iron it is peroxidised and the ground assumes a yellow colour4 ,the thickness of yellow earth in the mines is therefore a measure of the depth of penetration of air and moisture4 ,the colour does not affect the yield of diamonds4 ,besides diamonds1 there have been detected more than eighty species of minerals in the blue ground1 the more common being magnetite1 ilmenite1 garnet1 bright green ferriferous enstatite 7bronzite71 a hornblendic mineral closely resembling smaragdite1 calc-spar1 vermiculite1 diallage1 jeffreysite1 mica1 kyanite1 augite1 peridot1 eclogite1 iron pyrites1 wollastonite1 vaalite1 zircon1 chrome iron1 rutile1 corundum1 apatite1 olivine1 sahlite1 chromite1 pseudobrookite1 perofskite1 biotite1 and quartz4 ,the blue ground does not show any signs of passing through great heat1 as the fragments in the breccia are not fused at the edges4 ,the eruptive force was probably steam or water-gas1 acting under great pressure1 but at no high temperature4 ,according to ,mr4 ,dunn1 in the ,kimberley ,mine1 at a depth of #abj feet1 several small fresh-water shells were discovered in what appeared to be undisturbed material4 ,a selection of thin sections of some of these rocks and minerals1 mounted as microscopic objects and viewed by polarised light1 are not only of interest to the geologist1 but are objects of great beauty4 ,the appearance of shale and fragments of other rocks testify that the mlange has suffered no great heat in its present condition1 and that it has been erupted from great depths by the agency of water vapour or some similar gas4 ,the rock outside the pipes and encasing them is called 8reef40 ,inside some of the mines occur large masses of 8floating reef10 covering an area of several thousand square feet4 ,in the ,de ,beers ,mine is what is called 8the snake10 a dyke of igneous rock taking a serpentine course across the mine1 and standing like a vein nearly vertical1 varying in thickness from #b to #g feet4 ,the main body of the blue ground is entirely analogous to the snake rock1 naturally more decomposed1 but in essential points the microscopic appearance of the blue ground and of the 8snake0 is in an extraordinary degree alike4 ,mr4 ,gardner ,williams supposes that the 8snake0 is a younger eruptive formation coming from the same volcanic source as the blue ground4 ,no diamonds have been found either in the 8snake0 or the floating reef4 ,the ground1 however1 is generally richer in diamonds in the neighbourhood of the floating reef4 ,before the discovery of the mines there was nothing in the superficial appearance of the ground to indicate the treasures below4 ,since the volcanic ducts were filled with the diamantiferous ground1 denudation has planed the surface and the upper parts of the craters1 and other ordinary signs of volcanic activity being smoothed away1 the superficial and ubiquitous red sand covered the whole surface4 ,the ,kimberley ,mine seems to have presented a slight elevation above the surrounding flat country1 while the sites of other mines were level or even slightly depressed4 ,the ,wesselton ,mine1 within a mile of ,dutoitspan1 has only been discovered a few years4 ,it showed a slight depression on the surface1 which had been used as a shoot for dry rubbish4 ,there are other diamantiferous pipes in the neighbourhood1 but they are small and do not contain stones in payable quantities4 ,more recently another diamantiferous pipe has been discovered about #dj miles off1 near ,klipdam1 and is now worked as the ,leicester ,mine4 ,other hoards of diamonds may also be near2 where there are no surface signs1 and the pipe itself is hidden under #aj or #bj feet of recent deposits1 it is impossible to prospect the entire country4 ,accident has hitherto been the chief factor in the discovery of diamond mines4 ,how the great pipes were originally formed is hard to say4 ,they were certainly not burst through in the ordinary manner of volcanic eruption1 since the surrounding and enclosing walls show no signs of igneous action1 and are not shattered or broken up even when touching the 8blue ground40 ,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 volcano1 together with all kinds of debris eroded from the rocks through which it erupted4 ,the direction of flow is seen in the upturned edges of some of the strata of shale in the walls1 although ,i was unable to see any upturning in most parts of the walls of the ,de ,beers ,mine at great depths4 ,,the ,,kimberley ,,mine ,,in ,,old ,,days ,according to ,mr4 ,paterson1 who examined the diamond fields of ,kimberley soon after their discovery1 8,wherever the diamond is obtained perfect in form and smooth in finest smoothness of surface1 without depression1 hump1 or twist of any kind1 such diamonds were ever found in their own little moulds of finest limey stuff1#b and as if such mould of lime had been a necessity to their perfect formation4 ,and further1 where the splinters of diamonds1 or boarty stuff1 were chiefly met by the diggers1 there was much less presence of limey matter in the claim at the section of it where such broken or fragmentary diamonds were found2 and that chiefly from among what the diggers termed #8clay-ballast1' or #8burnt brick1' were unearthed the bits or undeveloped crystals so plentiful at ,new ,rush40#c ,in the first days of diamond mining there was no idea that diamantiferous earth extended to any particular depth1 and miners were allowed to dig holes at haphazard and prospect where they liked4 ,when the ,kimberley ,mine was discovered a new arrangement was made1 and in ,july1 #ahga1 it was cut up into about #ejj claims1 each #ca feet square1 with spaces reserved for about fifteen roadways across the mine4 ,no person at first could hold more than two claims--a rule afterwards modified4 ,the following quotation from a description of a visit to ,kimberley in #ahgb1 by ,mr4 ,paterson1 taken from a paper read by him to the ,geologists' ,association1 gives a graphic picture of the early days of the ,kimberley ,mine3 8,the ,new ,rush diggings 7as the ,kimberley ,mine was at first called7 are all going forward in an oval space enclosed around by the trap dyke1 and of which the larger diameter is about #ajjj feet1 while the shorter is not more than #gjj feet in length4 ,here all the claims of #ca feet square each are marked out with roadways of about #ab feet in width1 occurring every #fj feet4 ,upon these roadways1 by the side of a short pole fixed into the roadway1 sits the owner of the claim with watchful eye upon the ,kafir diggers below1 who fill and hoist1 by means of a pulley fixed to the pole above1 bucketful after bucketful of the picked marl stuff in which the diamonds are found4 8,many of the claims are already sunk to a depth of #ajj feet1 and still the diamonds continue to be found as plentifully as ever4 ,from the roadway above the marl is carted away to the sorting-tables1 outside the range of the diggings1 among mounds of marl stuff which seem like little hills4 ,here1 amidst such whirls of dust as are nowhere else seen1 the marl stuff is pounded1 sifted from the finest powder of lime and clay1 and from the residue put on the sorting-tables1 the diggers1 with a piece of zinc #i inches long by #d inches in breadth1 search out in the successive layers taken from the heap the precious gems4 ,i need not tell you that the search is by no means very perfect1 or that perhaps as many diamonds escape the digger's eye as are discovered and taken out by him1 but you will perhaps confess with me that their aptness in picking out the diamonds is by no means to be despised1 when ,i tell you that in one six months from the date of opening ,new ,rush diggings1 little short of a million sterling in diamonds has been extracted from them4 ,at close of day the diggers take daily stock of their finds1 and between five and six o'clock in the afternoon are to be seen hundreds and hundreds moving through the main street of ,new ,rush on visits to the tents of the buyers1 seated behind their little green baize tables1 with scales all ready1 and bags of gold and silver and piles of banknotes1 to buy the little gems40 ,it may help to realise the enormous value of the ,kimberley ,mine if ,i say that two claims1 measuring together #fb by #ca feet and worked to a depth of #aej feet1 yielded #bh1jjj carats of diamonds4 ,the roadways across the mine soon1 however1 became unsafe4 ,claims were sunk #ajj or #bjj feet each side of a roadway1 and the temptation to undermine roadways was not always resisted4 ,falls of road frequently took place1 followed by complete collapse1 burying mine and claims in ruin4 ,at that time there were probably #ab1jjj or #ae1jjj men at work in the mine1 and then came the difficulty how to continue working the host of separate claims without interference with each other4 ,a system of rope haulage was adopted4 ,the following description of the work at the ,kimberley ,mine at this stage of its history is given by ,mr4 ,reunert3#d 8,a succession of tall1 massive timber stagings was erected round the margin of the mine4 ,each staging carried two or three platforms one above the other1 every platform serving as an independent level from which to communicate with the claims below4 ,stationary ropes were then stretched from the different levels of the stagings to the claims1 the ropes being anchored to the ground at both ends3 the upper platforms communicated with the claims in the centre of the mine1 the lower platforms with those nearer the margin4 ,the hauling ropes were attached to windlasses worked by ,kafirs on the several platforms1 on which grooved guide wheels for the ropes were also fixed1 the buckets being swung from the stationary ropes by little overhead runners and crooks4 ,arrived at the level of the platform the bucket was tipped into a narrow shoot1 down which the ground ran into a bag held ready to receive it1 in which it was conveyed away to be sorted4 ,the din and rattle of these thousands of wheels and the twang of the buckets along the ropes were something deafening1 while the mine itself seemed almost darkened by the thick cobweb of ropes1 so numerous as to appear almost touching4 ,this mode of haulage continued in vogue during the whole of #ahgc1 and if the appearance of the mine was less picturesque than when the roadways existed1 it was1 if anything1 more unique4 ,by moonlight1 particularly1 it was a weird and beautiful sight40 ,the mine was now threatened in two other quarters4 ,the removal of the blue ground took away the support from the walls of the pipe1 and frequent falls of reef occurred1 not only covering up valuable claims with rubbish1 but endangering the lives of workers below4 ,moreover1 as the workings deepened1 water made its appearance1 necessitating pumping4 ,in #ahgh one quarter of the claims were covered by reef1 and in #ahgi over #cjj1jjj were spent on removing reef and water4 ,in #ahha over #bjj1jjj were thus spent1 and in #ahhb more than half a million sterling was needed to defray the cost of reef removal4 ,so matters went on until four million cubic yards of reef had been removed1 at a cost of two millions sterling1 and still little good was done1 for out of #djj claims in the mine only about fifty could be regularly worked4 ,ultimately1 in ,november1 #ahhc1 the biggest fall of reef on record took place1 estimated at #bej1jjj cubic yards1 surging half across the mine1 where the bulk of it lies to this day4 ,it became evident that open workings could not be carried on at such depths1 and after many experiments the present system of underground working was devised4 ,during this time of perplexity1 individual miners who could easily have worked one or two claims near the surface could not continue work in the face of harassing difficulties and heavy expenses4 ,thus the claims gradually changed hands until the mine became the property first of a comparatively small number of capitalists1 then of a smaller number of limited liability companies1 until finally the whole of the mines have practically become the property of the 8,de ,beers ,consolidated ,mines1 ,limited40 ,,chapter ,,iii ,,kimberley ,,mines ,,at ,,the ,,present ,,day ,the ,de ,beers ,consolidated ,mines1 ,limited1 was founded in #ahhh1 mainly through the genius of the late ,cecil ,john ,rhodes1 for the purpose of acquiring all-important diamond-mining interests in the ,kimberley area and thereby controlling the output4 ,the two richest mines1 ,kimberley and ,de ,beers1 have been actively worked ever since1 and have been the main contributors to an output which now realises over five millions sterling annually4 ,dutoitspan ,mine was completely closed down1 and practically the whole of ,bultfontein was kept idle for many years2 but with a view to the requirements of the future and the marked increase in the demand for diamonds1 notwithstanding the steady rise in prices that has taken place1 both these mines have now been equipped for underground working on a grand scale4 ,the youngest of the ,de ,beers group of mines is the ,wesselton1 which was discovered in #ahij by the late ,mr4 ,h4 ,a4 ,ward1 and soon afterwards purchased by ,mr4 ,rhodes on behalf of the ,company4 ,the mine is now being worked opencast on a magnificent scale and has largely exceeded original expectations 7,fig4 #e74 ,the success of the consolidation is proved by the fact that since it was brought about #bb1jjj1jjj have been paid in dividends to the shareholders1 and it is roughly estimated that #dj1jjj1jjj carats of diamonds have been produced of a total value of eighty millions4 ,illustration3 ,,fig4 #e4 ,,wesselton ,,diamond ,,mine4 ,,open ,,workings4 ,to face p4 #cd4 ,at the four mines about #hjjj persons are daily employed1 namely1 #aejj whites and #fejj blacks4 ,the wages are1 whites1 #e or #f a week2 blacks1 underground1 #ds4 to #es4 a day1 and aboveground1 #bas4 a week4 ,,the ,,compound ,,system ,with gems like diamonds1 where so large an intrinsic value is concentrated into so small a bulk1 it is not surprising that robbery has to be guarded against in the most elaborate manner4 ,the ,illicit ,diamond ,buying 7,i4,d4,b47 laws are very stringent1 and the searching1 rendered easy by the 8compounding0 of the natives--which ,i shall describe presently--is of the most drastic character 7,fig4 #f74 ,it is1 in fact1 very difficult for a native employee to steal diamonds2 even were he to succeed1 it would be almost impossible to dispose of them1 as a potential buyer would prefer to secure the safe reward for detecting a theft rather than run the serious risk of doing convict work on the ,cape ,town ,breakwater for a couple of years4 ,i heard of a native who1 secreting a diamond worth several hundreds of pounds1 after trying unsuccessfully to sell it1 handed it back to the manager of his compound1 glad to get the sixpence a carat to which he was entitled4 ,before the passing of the 8,diamond ,trade ,act0 the value of diamonds stolen reached nearly one million sterling per annum4 ,a 8compound0 is a large enclosure about #bj acres in extent1 surrounded by rows of one-story buildings of corrugated iron4 ,these are divided into rooms holding each about twenty natives4 ,a high iron fence is erected around the compound1 #aj feet from the buildings4 ,within the enclosure is a store where the necessaries of life are supplied to the natives at a reduced price1 wood and water being provided free of charge4 ,in the middle is a large swimming-bath1 with fresh water running through it4 ,the rest of the space is devoted to recreation1 games1 dances1 concerts1 and any other amusement the native mind can desire4 ,i have to thank the superintendents of the respective compounds1 who spoke all the native dialects1 for their kindness in showing us round1 and suggesting dances and concerts1 got up at ten minutes' notice1 for the benefit of my camera4 ,the dancing was more of the character of attitudinising and marching to a monotonous tum-tum1 the 8orchestra0 consisting of various-sized drums and what they call a piano--an octave or so of tuned slabs of wood held in order on stretched strings and struck with a wooden hammer4 ,the native music as a rule is only marking time1 but ,i have heard musical melodies accompanying some of their songs4 ,in case of accident or illness there is a well-appointed hospital where the sick are tended4 ,medical supervision1 nurses1 and food are supplied free by the ,company4 ,in the compound are to be seen representatives of nearly all the picked types of ,african tribes4 ,each tribe keeps to itself1 and to go round the buildings skirting the compound is an admirable object-lesson in ethnology4 ,at one point is a group of ,zulus2 next we come to ,fingoes2 then ,basutos2 beyond come ,matabele1 ,bechuanas1 ,pondos1 ,shangains1 ,swazis1 and other less-known tribes1 either grouped or wandering around making friendly calls4 ,the clothing in the compound is diverse and original4 ,some of the men are evident dandies1 whilst others think that in so hot a climate a bright-coloured handkerchief or 8a pair of spectacles and a smile0 is as great a compliance with the conventions of civilisation as can be expected4 ,the natives are not interfered with in their various amusements1 always provided they do not make themselves objectionable to their neighbours4 ,they soon learn that tribal animosities are to be left outside the compound4 ,one ,sunday afternoon my wife and ,i walked unattended about the compound1 almost the only whites present among #agjj natives4 ,the manners of the fold were so friendly1 and their smiles so cordial1 that the idea of fear vanished4 ,at one part a ,kafir was making a pair of trousers with a bright nickel-plated sewing-machine1 in which he had invested his savings2 next to him a 8boy0 was reading from the ,testament in his own language to an attentive audience2 in a corner a party were engaged in cooking a savoury mess in an iron pot2 further on the orchestra was tuning up and ,zulus were putting the finishing touches to their toilet of feathers and beads4 ,one group was intently watching a mysterious game4 ,it is played by two sides1 with stones and grooves and hollows in the ground1 and appears of most absorbing interest4 ,it seems to be universal throughout ,africa2 it is met with among the ruins of ,zimbabwe1 and signs of it are recorded on old ,egyptian monuments4 ,i wanted to learn it1 and an intelligent ,zulu player offered to teach it to me in a few minutes4 ,captain ,dallas1 however1 with a more accurate opinion of my intelligence than my friend the ,zulu1 assured me it would take months before ,i could begin to know anything about it4 ,he had tried for years and could make nothing of it4 ,illustration3 ,,fig4 #f4 ,,de ,,beers ,,compound4 ,illustration3 ,,fig4 #g4 ,,de ,,beers ,,mine4 ,,underground ,,workings4 ,to face p4 #dj4 ,they get good wages1 varying according to occupation4 ,the work is appreciated1 and there are always more applicants than can be accepted4 ,on entering1 the restrictions to which they must submit are fully explained1 and they are required to sign for three months at least1 during which time they must not leave the compound or mine4 ,a covered way and tunnel lead the workers underground to the down shaft1 while those working on the depositing floors go and come under guard4 ,it is seldom that a man does not return once he has lived the life in the compound2 some come again and again for years1 only leaving occasionally to spend accumulated savings4 ,the most careful men save money1 and carry it at intervals to the superintendent to keep for them4 ,occasionally they ask to look at their savings1 which may amount to #cj or #dj1 accumulated by driblets4 ,they are ignorant of savings banks or interest1 and are content if they see their own money in the original rags and papers4 ,the ,kafir1 on demand1 must behold his coins just as he handed them in1 wrappings and all4 ,sometimes the superintendent will have as much as #ajjj of savings in his care4 ,on leaving1 the men generally draw all their savings1 and it is not uncommon for a grateful ,kafir to press #b or #c on ,captain ,dallas in recognition of his trouble4 ,they are astonished when their offerings are declined2 still more so when it is explained that if they would put their savings in a bank they would have a few extra pounds given to them for the privilege of taking care of it4 ,a shrewd young ,pondo1 who had been coming year after year1 applied for some of his savings1 and gave as a reason that he wanted to buy a wife4 8,but you said the same thing last year10 replied ,captain ,dallas2 8,i hope nothing has happened40 8,no10 said the man2 8one wife1 she quarrel with me2 two wives1 they quarrel with each other2 me peace60 ,,underground ,,workings ,in the face of constant developments ,i can only describe the system in use at the time of my own visits in #ahif and #aije4 ,shafts are sunk in the solid rock at a sufficient distance from the pipe to be safe against reef movements in the open mine4 ,in #aijc the rock shafts in the ,de ,beers and ,kimberley ,mines reached depths of #bjgf and #beii feet respectively4 ,tunnels are driven from these shafts at different levels1 about #abj feet apart1 to cross the mine from west to east4 ,these tunnels are connected by two other tunnels running north and south1 one near the west side of the mine and one midway between it and the east margin of the mine4 ,from the east and west tunnels offsets are driven to the surrounding rock4 ,when near the rock the offsets widen into galleries1 these in turn being stoped on the sides until they meet1 and upwards until they break through the blue ground4 ,the fallen reef with which the upper part of the mine is filled sinks and partially fills the open space4 ,the workmen then stand on the fallen reef and drill the blue ground overhead1 and as the roof is blasted back the debris follows4 ,when stoping between two tunnels the blue is stoped up to the debris about midway between the two tunnels4 ,the upper levels are worked back in advance of the lower levels1 and the works assume the shape of irregular terraces4 ,the main levels are from #ij to #abj feet apart1 with intermediate levels every #cj feet4 ,hoisting is done from only one level at a time through the same shaft4 ,by this ingenious method every portion of blue ground is excavated and raised to the surface1 the rubbish on the top gradually sinking and taking its place4 ,the scene below ground in the labyrinth of galleries is bewildering in its complexity1 and very unlike the popular notion of a diamond mine 7,fig4 #g74 ,all below is dirt1 mud1 grime2 half-naked men1 dark as mahogany1 lithe as athletes1 dripping with perspiration1 are seen in every direction1 hammering1 picking1 shovelling1 wheeling the trucks to and fro1 keeping up a weird chant which rises in force and rhythm when a greater task calls for excessive muscular strain4 ,the whole scene is more suggestive of a coal mine than a diamond mine1 and all this mighty organisation1 this strenuous expenditure of energy1 this costly machinery1 this ceaseless toil of skilled and black labour1 goes on day and night1 just to win a few stones wherewith to deck my lady's finger6 ,all to gratify the vanity of woman6 8,and10 interposed a lady who heard this remark1 8the depravity of man60 ,,the ,,depositing ,,floors ,owing to the refractory character of blue ground fresh from the mines1 it has to be exposed to atmospheric influences before it will pulverise under the action of water and mechanical treatment4 ,from the surface-boxes1 into which the blue ground is tipped when it reaches the top of the main shaft1 it is transferred to side-tipping trucks and sent to the depositing floors by means of endless wire-rope haulage4 ,the speed of the haulage varies from #b to #d miles per hour4 ,the trucks are counted automatically as they are sent to the floor by a reciprocating engine-counter placed on a frame near the tramline4 ,the depositing floors are prepared by removing the bush and grass from a fairly level piece of ground2 this ground is then rolled smooth and hard4 ,the floors extend over many square miles of country and are surrounded by #g-;foot barbed wire fences1 vigilantly guarded day and night4 ,the ,de ,beers floors1 on ,kenilworth1 are laid off in rectangular sections #fjj yards long and #bjj yards wide1 each section holding about #ej1jjj loads4 ,the ground from the ,kimberley ,mine is the softest and only needs a few months' exposure on the floors2 the ground from ,de ,beers is much harder and requires at least six months' exposure1 while some ground is so hard that it will not disintegrate by exposure to the weather under one or two years4 ,the ,de ,beers ,mine contains a much larger quantity of this hard blue ground than the other mines1 and in order to save the loss of time consequent on keeping an enormous stock of blue constantly on the floors1 it has recently been decided to pass the harder and more refractory stuff direct from the mine through crushing mills4 ,for a time the blue ground remains on the floors without undergoing much alteration4 ,but soon the heat of the sun and moisture produce a wonderful effect4 ,large pieces1 hard as ordinary sandstone when taken from the mine1 commence to crumble4 ,at this stage the winning of the diamonds assumes more the nature of farming than mining4 ,the ground is frequently harrowed and occasionally watered1 to assist pulverisation by exposing the larger pieces to atmospheric influences4 ,the length of time necessary for the ground to weather before it becomes sufficiently pulverised for washing depends on the season of the year and the amount of rain4 ,the longer the ground remains exposed the better it is for washing4 ,illustration3 ,,fig4 #h4 ,,de ,,beers ,,washing ,,and ,,concentrating ,,machinery4 ,to face p4 #dh4 ,it is curious to note that there is a marked difference in the rapidity of disintegration of the blue ground in each of the four mines4 ,the longer the exposure1 the more complete the pulverisation and the better for washing4 ,under normal conditions soft blue ground becomes sufficiently pulverised in from four to six months1 but it is better to expose it for a longer period1 even for a whole year4 ,,washing ,,and ,,concentrating ,,machinery ,after the blue ground has been weathered for a sufficient time1 it is again loaded into trucks and hauled to the crushing machinery 7,fig4 #h74 ,the first or 8comet0 crushers reduce the ground so that it will pass into hoppers and thence into revolving cylinders covered with perforated steel plates1 having holes #a inches in diameter which separate the finely crushed from the coarse pieces4 ,pieces larger than #a inches pass out of the end of the cylinders and fall upon a conveyor belt1 which takes them to the end of the machine--these pieces are mostly waste rock which is found in the blue ground4 ,the fine ground which passes through the holes in the cylinder1 together with a plentiful current of water1 flows into the washing pans4 ,these pans are of iron1 #ad feet in diameter1 furnished with ten arms each having six or seven teeth4 ,the teeth are so set as to form a spiral1 so that when the arms revolve the teeth carry the heavy deposit to the outer rim of the pan1 while the lighter material passes towards the centre and is carried from the pan by the flow of water4 ,the heavy deposit contains the diamonds4 ,it remains on the bottom of the pan and near its outer rim4 ,this deposit is drawn off every twelve hours by means of a broad slot in the bottom of the pan4 ,the average quantity of blue ground passed through each pan is from #djj to #dej loads in ten hours4 ,the deposit left in each pan after putting the above number of loads through amounts to three or four loads1 which go to the pulsator for further concentration4 ,about #ad per cent of all the ground sent to the depositing floors is too hard to weather1 so of late years crushing and concentrating plant has been erected to deal effectually with the hard lumps1 thus saving the great lock-up of capital consequent on letting them lie on the floor a year or two4 ,the hard lumps being hauled to the upper part of the machine1 are tipped into bins1 whence they pass to crushing rollers which so reduce them that they will pass through a ring two inches in diameter4 ,the coarse powder is screened through revolving cylinders having -inch and #a-;inch perforations4 ,the stuff passing through the finer holes goes to the finishing mill1 while the coarser stuff goes to smaller crushers4 ,before the coarse lumps are re-crushed they pass over revolving picking tables1 where any specially large diamonds are rescued1 thus preventing the risk of breakage4 ,from the picking tables the ground is scraped automatically into two sets of rolls1 and the pulverised product screened again and graded into three sizes4 ,the finest size1 passing a -inch screen1 goes to the washing pans1 and the two coarser sizes to jigs4 ,large diamonds which have been separated from their envelope of blue are retained in the jig4 ,the ground still holding the smaller diamonds passes out of the end of the jig and then through a series of rolls1 screens1 and jigs until the diamantiferous gravel is drawn from the bottom jigs into locked trucks running on tramways to the pulsator for further concentration and sorting4 ,the pulsator is an ingeniously designed but somewhat complicated machine for dealing with the diamantiferous gravel already reduced one hundred times from the blue ground1 the pulsator still further concentrating it till the gravel is rich enough to enable the stones to be picked out by hand4 ,the value of the diamonds in a load of original blue ground being about #cjs41 the gravel sent to the pulsator from the pans1 reduced a hundredfold1 is worth #aej a load4 ,stuff of this value must not be exposed to risk of peculation4 ,the locked trucks are hoisted by a cage to a platform1 where they are unlocked and their contents fed into a shoot leading to a cylinder covered with steel sieving with holes from #a_/af to of an inch in diameter4 ,the five sizes which pass through the cylinder flow upon a combination of jigs1 termed at the mines the pulsators4 ,the bottoms of the jigs are covered with screens1 or sieving1 the meshes of which are a little larger than the holes in the revolving cylinder immediately at the back of them4 ,over each screen is spread a layer of bullets to prevent the rich deposit from passing too rapidly through the screens4 ,the jigs themselves are stationary1 but from below an intermittent stream of water passes in rapid pulsations with an up and down movement4 ,this pulsation keeps the diamantiferous gravel constantly moving--8alive0 is the expressive word used--and tends to sort out the constituents roughly according to their specific gravity1 the heavier particles working to the bottom and the lighter material washing off by the flow of water and passing into trucks1 whence it is carried to the tailings heap4 ,the heavier portions1 by the up and down wash of the water1 gradually work their way under the bullets and pass through the screens into pointed boxes1 whence the heavy concentrates are drawn off upon endless belts4 ,these convey their precious load to small elevators by means of which the concentrates are lifted into hoppers from which they are fed upon shaking tables4 ,illustration3 ,,fig4 #i4 ,,sorting ,,concentrates ,,for ,,diamonds4 ,,de ,,beers4 ,to face p4 #ed4 ,,chapter ,,iv ,,collecting ,,the ,,gems ,the sorting room in the pulsator house is long1 narrow1 and well lighted 7,fig4 #i74 ,here the rich gravel is brought in wet1 a sieveful at a time1 and is dumped in a heap on tables covered with iron plates4 ,the tables at one end take the coarsest lumps1 next comes the gravel which passed the -inch holes1 then the next in order1 and so on4 ,the first sorting is done by thoroughly trustworthy white men2 for here the danger of robbery is greatest4 ,sweeping the heap of gravel to the right1 the sorter scrapes a little of it to the centre of the table by means of a flat piece of sheet zinc4 ,with this tool he rapidly passes in review the grains1 seizes the diamonds and puts them into a little tin box in front of him4 ,the stuff is then swept off to the left and another lot taken1 and so on till the sieveful of gravel is exhausted1 when another is brought in4 ,the stuff the sorter has passed to his left as temporarily inspected is taken next to another part of the room1 where it is again scrutinised by native convicts again and again1 and whilst diamonds can be found in quantity sufficient to repay the cost of convict labour1 it is passed under examination4 ,the diamond has a peculiar lustre1 and on the sorter's table it is impossible to mistake it for any other stone that may be present4 ,it looks somewhat like clear pieces of gum arabic1 with a sort of intrinsic lustre which makes a conspicuous shine among the other stones4 ,,automatic ,,diamond ,,collector ,a series of experiments was initiated by ,mr4 ,gardner ,williams with the object of separating the diamonds from the heavy1 valueless concentrates with which they are associated4 ,an ordinary shaking or percussion table was constructed1 and every known means of separation was tried without success4 ,one of the employees of ,de ,beers1 ,mr4 ,fred ,kirsten1 was in charge of the experimenting1 under the supervision of the late ,mr4 ,george ,labram1 the manager of the large crushing plant1 and afterwards mechanical engineer to the ,company4 ,notwithstanding the fact that the specific gravity of the diamond 7#ceb7 was less than that of several of the minerals associated with it1 so that its separation would seem a simple matter1 it was found in practice to be impossible owing to the slippery nature of the diamond4 ,the heavy concentrates carried diamonds1 and diamonds flowed away from the percussion table with the tailings4 ,when it seemed that every resource to do away with hand-sorting had been exhausted1 ,kirsten asked to be allowed to try to catch the diamonds by placing a coat of thick grease on the surface of the percussion table with which the other experiments had been made4 ,kirsten had noticed that oily substances1 such as axle grease and white or red lead1 adhered to diamonds when they chanced to come into contact1 and1 he argued to himself1 if these substances adhered to diamonds and not to the other minerals in the concentrates1 why should not diamonds adhere to grease on the table and the other minerals flow away8 ,in this way the remarkable discovery was made that diamonds alone of all minerals contained in the blue ground will adhere to grease1 and that all others will flow away as tailings over the end of the percussion table with the water4 ,after this was determined by thorough experiments1 more suitable shaking tables were constructed at the ,company's workshops4 ,these were from time to time improved upon1 until now all the sorting 7except for the very coarse size7 is done by these machines1 whose power of distinction is far superior to the keenest eye of the native4 ,only about of #a per cent of diamonds is lost by the first table1 and these are recovered almost to a stone when the concentrates are passed over the second table4 ,the discrimination of this sorter is truly marvellous4 ,native workers1 although experienced in the handling of diamonds1 often pick out small crystals of zircon1 or ,dutch boart1 by mistake1 but the senseless machine is practically unerring4 ,the grease containing the diamonds1 together with a small percentage of very heavy minerals1 such as iron pyrites and barytes1 is scraped from the tables1 placed in buckets made of steel plates with fine perforations1 and boiled or steamed4 ,the grease passes away to tanks of water1 where it is cooled and is again fit for use4 ,the diamonds1 together with small bits of iron pyrites1 brass nails from the miners' boots1 pieces of copper from the detonator used in blasting1 which remain on the tables owing to their high specific gravity1 and a very small admixture of worthless deposit which has become mechanically mixed with the grease1 are then boiled in a solution containing caustic soda1 where they are freed from all grease4 ,the quantity of deposit from the size of of an inch downwards1 which now reaches the sorting table1 does not exceed #a cubic foot for every #ab1jjj loads 7#aib1jjj cubic feet7 of blue ground washed4 ,as already stated1 #e_/ab of #a per cent of the whole mass of blue formerly passed to the sorting tables2 or1 from #ab1jjj loads1 which is about the daily average of the quantity washed at ,de ,beers and ,kimberley ,mines1 #hjj cubic feet had to be assorted by hand4 ,,the ,,yield ,,of ,,diamonds ,sometimes as many as #hjjj carats of diamonds come from the pulsator in one day1 representing about #bj1jjj in value4 ,when the bare statement is made that nearly #e1jjj1jjj truck-loads1 or more than #d1jjj1jjj tons of blue ground1 have been washed in a year1 the mind only faintly conceives the prodigious size of the mass that is annually drawn from the old craters and laboriously washed and sorted for the sake of a few bucketfuls of diamonds4 ,it would form a cube of more than #dcj feet1 or a block larger than any cathedral in the world1 and overtopping the spire of ,st4 ,paul's1 while a box with sides measuring #b feet #i inches would hold the gems4 ,from two to three million carats of diamonds are turned out of the ,de ,beers mines in a year1 and as #e1jjj1jjj carats go to the ton1 this represents half a ton of diamonds4 ,to the end of #ahib #aj tons of diamonds had come from this mine1 valued at #fj1jjj1jjj sterling4 ,this mass of blazing diamonds could be accommodated in a box #e feet square and #f feet high4 ,the diamond is a luxury1 and there is only a limited demand for it throughout the world4 ,from four to four and a half millions sterling is as much as is spent annually in diamonds2 if the production is not regulated by the demand1 there will be over-production1 and the trade will suffer4 ,by regulating the output the directors have succeeded in maintaining prices since the consolidation in #ahhh4 ,the blue ground varies in its yield of diamonds in different mines1 but is pretty constant in the same mine4 ,in #ahij the yield per load of blue ground was3 ,,carats ,from the ,kimberley ,mine from #abe to #ae 0 ,de ,beers ,mine 0 #abj 0 #ac 0 ,dutoitspan ,mine 0 #jag 0 #je 0 ,bultfontein ,mine 0 #je 0 #jcc ,,varieties ,,of ,,diamonds ,,fancy ,,stones ,diamonds occur in all shades1 from deep yellow to pure white and jet black1 from deep brown to light cinnamon1 also green1 blue1 pink1 yellow1 orange1 and opaque4 ,both in ,kimberley and ,de ,beers the blue ground on the west side is poorer in diamonds than the blue ground in other parts of the mines4 ,the diamonds from the west side also differ somewhat from those in other parts of the same mine4 ,the diamonds from each mine have a distinctive character1 and so uniform are the characteristics that an experienced buyer can tell at once the locality of any particular parcel of stones4 ,an isolated stone may1 of course1 be found occasionally in any one mine which is characteristic of some other source of production1 but this is the exception to the general rule4 ,there is a great similarity between the produce of the ,de ,beers and ,kimberley mines4 ,a day's wash from either of these mines could be distinguished from each other1 but not so easily the majority of the individual stones4 ,the ,kimberley ,mine produces a small percentage of white crystals1 octahedral in shape1 is noted for its large macles1 and1 in common with the ,de ,beers ,mine1 it also yields a large percentage of coloured and large yellow diamonds4 ,the ,de ,beers ,mine produces a comparatively small percentage of really white diamonds1 but is noted for its fine silvery capes4 ,the ,dutoitspan ,mine is noted for its fine white cleavages1 silver capes1 large yellows1 and an exceptional proportion of large stones generally4 ,it also produces a small proportion of fine white1 octahedral-shaped crystals and a comparatively small proportion of diamonds below #jb of a carat in size4 ,the ,bultfontein ,mine produces a very large percentage of white diamonds1 mostly octahedral in shape and generally small in size4 ,it produces very few coloured stones1 but a larger percentage of flawed and spotted stones than any other mine4 ,even the apparently pure stones from this mine frequently develop flaws in cutting1 which in the rough were imperceptible to the naked eye4 ,the ,wesselton ,mine diamonds are noted for an abnormally large percentage of octahedral stones1 a large proportion of which are free from flaws4 ,white and brown stones predominate in this mine2 there is almost an entire absence of the ordinary yellow1 but very fine golden-coloured fancy stones are unearthed occasionally1 invariably in the form of cleavage1 and hardly ever exceeding #b carats each in weight4 ,for 8golden fancies0 this mine is unrivalled4 ,wesselton diamonds are easily distinguished from the produce of every other mine by a decided gloss common to them4 ,wesselton produces more stones of #aj carats each and over than ,bultfontein1 but comparatively few large stones of over #ej carats each4 ,it produces a very large percentage of small diamonds under #jb of a carat4 ,with ,bultfontein it shares the distinction of yielding cubical stones occasionally4 ,it also produces a small percentage of blue-whites4 ,the ,frank ,smith ,mine produces very fine white diamonds1 fairly regular in shape1 mostly octahedral1 and hardly any coloured stones4 ,many of the stones are grooved at the edges4 ,the ,kamfersdam ,mine yields diamonds of very inferior quality1 dark brown being the predominating colour1 and even the majority of the better-class stones from this mine are faintly tinged with brown4 ,the ,kimberley ,west1 formerly known as ,theron's ,mine1 situated about #cj miles due west of ,kimberley1 yields a very small percentage of blue-whites1 fine 8silver capes10 and a large proportion of brown diamonds1 somewhat better in quality than ,kamfersdam and more regular in shape4 ,the diamonds from this mine present a distinctly 8alluvial0 appearance1 but they are nevertheless distinctive in character from river diamonds and much inferior in quality4 ,the diamonds from the ,leicester ,mine are of a distinctive character2 they are very much grooved1 extremely bad shapes for cutting1 and many of the stones are cross-grained4 ,the ,newlands ,mine1 ,west ,griqualand1 about #dj miles north-west of ,kimberley1 is interesting on account of the occurrence of diamond in what the ,reverend ,professor ,bonney considers to be its true matrix4 ,the workmen occasionally come across well-rounded1 boulder-like masses of eclogite1 a rather coarsely crystalline rock1 sometimes more than a foot in diameter4 ,some of these boulders have diamonds imbedded in them4 ,one piece examined by ,professor ,bonney measured approximately #d inches by #c inches by #b inches1 and appeared to have been broken off a larger eclogite boulder4 ,in it were seen ten diamonds1 mostly well-crystallised octahedra1 perfectly colourless1 with brilliant lustre1 four of them being comprised within a space of a quarter of an inch square4 ,all these diamonds were on the surface4 ,probably others would have been found inside1 but it was not considered desirable to destroy the specimen by breaking it up4 ,it is now in the ,natural ,history ,museum1 having been presented by the ,directors of the ,newlands ,mine4 ,eclogite has been found in other diamond mines1 but ,i am not aware that diamonds have been found imbedded in it except in the ,newlands ,mine4 ,stones from ,jagersfontein1 in the ,orange ,river ,colony1 display great purity of colour and brilliancy1 and they have the so-called 8steely0 lustre characteristic of old ,indian gems4 ,,falling ,,off ,,of ,,yield ,,with ,,depth ,according to tables furnished by the ,de ,beers ,company1 the yield of the ,de ,beers and ,kimberley mines has declined as the depth increases4 ,at the same time the value of the stones has risen1 and diamonds are more expensive to-day than at any previous time4 ,,number ,,of ,,value ,,year ,,carats#e ,,per ,,carat ,,per ,,load s4 d4 #ahhi #abhc #ai #hge #ahij #aae #cb #fge #ahia #jii #bi #f #ahib #jib #be #f #ahic #aje #bi #jf #ahid #jhi #bd #eb #ahie #jhe #be #f #ahif #jia #bf #id #ahig #jib #bf #ajf #ahih #jhj #bf #fb #ahii #jga #bi #gb #aijj #jfg #ce #ajb #aija #jgf #ci #g #aijb #jgf #df #eg #aijc #jfa #dh #fc #aijd #jed #dh #aah ,,stones ,,other ,,than ,,diamonds ,accompanying diamonds in the concentrates are a number of other minerals of high specific gravity1 and some of notable beauty4 ,among these are the rich red pyrope 7garnet71 sp4 gr4 #cg1 containing from #ad to #c per cent of oxide of chromium2 zircon1 in flesh-coloured grains and crystals1 sp4 gr4 #d to #dg2 kyanite1 sp4 gr4 #cde to #cg1 discernible by its blue colour and perfect cleavage2 chrome diopside1 sp4 gr4 #cbc to #ce1 of a bright green colour2 bronzite1 sp4 gr4 #ca to #cc2 magnetite1 sp4 gr4 #di to #eb2 mixed chrome and titanium iron ore1 sp4 gr4 #dd to #di1 containing from #ac to #fa per cent of oxide of chromium1 and from #c to #fh per cent of titanic acid1 in1 changeable quantities2 hornblende1 sp4 gr4 #bi to #cd2 barytes1 sp4 gr4 #dc to #dg2 and mica4 ,some of the garnets are of fine quality1 and one was recently cut which resembled a pigeonblood ruby1 and attracted an offer of #be4 ,in the pulsator and sorting house most of the native labourers are long-sentence convicts1 supplied with food1 clothing1 and medical attendance by the ,company4 ,they are necessarily well guarded4 ,i myself saw about #ajjj convicts at work4 ,i was told that insubordination is very rare2 apart from the hopelessness of a successful rising1 there is little inducement to revolt2 the lot of these diamond workers is preferable to life in the ,government prisons1 and they seem contented4 ,illustration3 ,,fig4 #aj4 ,,de ,,beers ,,diamond ,,office4 #be1jjj ,,carats4 ,illustration3 ,,fig4 #aa4 ,,de ,,beers ,,diamond ,,office4 ,,the ,,valuators' ,,table4 ,to face p4 #gb4 ,,chapter ,v ,,the ,,diamond ,,office ,from the pulsator the diamonds are sent to the general office in ,kimberley to be cleansed in a boiling mixture of nitric and sulphuric acids4 ,a parcel of diamonds loses about half a part per #ajjj by this treatment4 ,on one of my visits to the diamond office the door opened and in walked two young men1 each carrying a large enamelled saucepan containing something steaming hot4 ,they went to one of the zinc-covered tables and turned out from the saucepans a lustrous heap of #be1jjj carats of diamonds 7,fig4 #aj74 ,they had just been boiled in acid and washed4 ,after purification the diamonds are handed to the valuators 7,fig4 #aa71 who sort them into classes1 according to size1 colour1 and purity4 ,in the diamond office they are sorted into ten classes4 ,in the year #ahie1 in #aadah carats of stones1 the proportions of the different classes were as follows3 ,close goods 7best stones7 #ech ,spotted stones #geh ,fine cleavage #gia ,flats #cie ,macles #cfe ,ordinary and rejection cleavage #bdcd ,rejection stones #dcb ,light and brown cleavage #efi ,rubbish #cgah ------ #ajjjj ------ ,fine sand #adah ------ #aadah ,it is a sight for ,aladdin to see the valuators at work in the strong-room of the ,de ,beers ,company at ,kimberley4 ,the tables are literally heaped with stones won from the rough blue ground--stones of all sizes1 purified1 flashing1 and of inestimable price2 stones that will be coveted by men and women all the world over2 and last1 but not least1 stones that are probably destined to largely influence the development and history of a whole huge continent4 ,,chapter ,,vi ,,noteworthy ,,diamonds ,prodigious diamonds are not so uncommon as is generally supposed4 ,diamonds weighing over an ounce 7#aeae carats7 are not unfrequent at ,kimberley4 ,some years ago1 in one parcel of stones1 ,i saw eight perfect ounce crystals1 and one stone weighing #b ounces 7,fig4 #ab74 ,the largest diamond from the ,kimberley mines weighed #dbh carats1 or nearly #d ounces troy4 ,it measured #a inch through the longest axis and was #a inch square4 ,after cutting it weighed #bbh carats1 losing #bjj carats in the process4 ,the largest known diamond was discovered in ,january1 #aije1 at the ,new ,premier ,mine1 near ,pretoria4 ,this mine is of the same type as the ,kimberley mines1 but larger in size1 and1 in fact1 is the largest known diamantiferous pipe in the world--the pipe containing the 8blue ground10 along the longer diameter of its oval-shaped cross-section1 measuring over half a mile1 and its area is estimated at #cej1jjj square yards4 ,this pipe breaks through felsitic rocks4 ,the diamond1 called 8,cullinan0 from the name of one of the directors of the company on whose farm it was discovered1 was presented to ,king ,edward on his birthday by the people of the ,transvaal4 ,it weighed no less than #cjbe carats1 or #iehfe grains 7#acg lb4 avoirdupois74 ,it was a fragment1 probably less than half1 of a distorted octahedral crystal2 the other portions still await discovery by some fortunate miner4 ,the frontispiece shows this diamond in its natural size1 from a photograph taken by myself4 ,i had an opportunity of examining and experimenting with this unequalled stone before it was cut4 ,a beam of polarised light passed in any direction through the stone1 and then through an analyser1 revealed colours in all cases1 appearing brightest when the light passed along the greatest diameter--about #d inches4 ,here the colours were very fine1 but no regular figure was to be seen4 ,round a small black spot in the interior of the stone the colours were very vivid1 changing and rotating round the spot as the analyser was turned4 ,these observations indicated internal strain4 ,illustration3 ,,fig4 #ab4 ,a ,,group ,,of ,,large ,,diamond ,,crystals4 ,to face p4 #gf4 ,the clearness throughout was remarkable1 the stone being absolutely limpid like water1 with the exception of a few flaws1 dark graphitic spots1 and coloured patches close to the outside4 ,at one part near the surface there was an internal crack1 showing well the colours of thin plates4 ,at another point there was a milky1 opaque mass1 of a brown colour1 with pieces of what looked like iron oxide4 ,there were four cleavage planes of great smoothness and regularity4 ,on other parts of the surface the crystalline structure was very marked4 ,the edges were rounded in parts1 and triangular markings 7depressions7 were to be seen4 ,i also noticed square depressions1 nearly as sharp and perfect as the triangular ones4 ,the cleaving and cutting and polishing of the ,cullinan diamond was entrusted to the firm of ,asscher and ,co41 in ,amsterdam4 ,the cleavage of the diamond was very successfully accomplished by ,mr4 ,joseph ,asscher4 ,an incision half an inch deep was made with a sharp diamond point in the proper place1 then a specially designed knife blade was placed in the incision and it was struck a heavy blow with a piece of steel4 ,the diamond split through a defective spot1 part of which was left in each portion of the diamond4 ,gigantic as is the ,cullinan diamond1 it represents in weight less than half the daily output of the ,de ,beers mines1 which averages about #gjjj carats per day4 ,next in size to the ,cullinan comes the one which was found at the ,jagersfontein ,mine4 ,it weighed #igj carats--over half a pound4 ,the following table gives the names and weights of some historic diamonds 7,fig4 #ac73 #a4 ,koh-i-noor1 after the second cutting1 #ajf carats4 #b4 ,loterie d',angleterre1 #di carats4 #c4 ,nizam of ,hyderabad1 #bgi carats4 #d4 ,orloff1 #aid carats4 #e4 ,koh-i-noor1 after first cutting1 #bgi carats4 #f4 ,regent or ,pitt1 #acg carats4 #g4 ,duke of ,tuscany1 #acc carats4 #h4 ,star of the ,south1 #abd carats4 #i4 ,pole ,star1 #dj carats4 #aj4 ,tiffany1 yellow1 #abe carats4 #aa4 ,hope1 blue diamond1 #dd carats4 #ab4 ,sancy1 #ec carats4 #ac4 ,empress ,eugenie1 #ea carats4 #ad4 ,shah1 #hf carats4 #ae4 ,nassak1 #gi carats4 #af4 ,pasha of ,egypt1 #dj carats4 #ag4 ,cullinan1 #cjbe carats4 #ah4 ,excelsior1 ,jagersfontein1 #ifi carats4 ,illustration3 ,,fig4 #ac4 ,,some ,,historic ,,diamonds4 ,to face p4 #hj4 ,,chapter ,,vii ,,boart1 ,,carbonado1 ,,and ,,graphite ,the black inclusions in some transparent diamonds consist of graphite4 ,on crushing a clear diamond showing such spots and heating in oxygen to a temperature well below the point at which diamond begins to burn1 ,moissan found that the grey tint of the powder disappeared1 no black spots being seen under the microscope4 ,there also occur what may be considered intermediate forms between the well-crystallised diamond and graphite4 ,these are 8boart0 and 8carbonado40 ,boart is an imperfectly crystallised diamond1 having no clear portions1 and therefore useless for gems4 ,shot boart is frequently found in spherical globules1 and may be of all colours4 ,ordinary boart is so hard that it is used in rock-drilling1 and when crushed it is employed for cutting and polishing other stones4 ,carbonado is the ,brazilian term for a still less perfectly crystallised form of carbon4 ,it is equally hard1 and occurs in porous masses and in massive black pebbles1 sometimes weighing two or more ounces4 ,the ash left after burning a diamond invariably contains iron as its chief constituent2 and the most common colours of diamonds1 when not perfectly pellucid1 show various shades of brown and yellow1 from the palest 8off colour0 to almost black4 ,these variations give support to the theory advanced by ,moissan that the diamond has separated from molten iron--a theory of which ,i shall say more presently--and also explain how it happens that stones from different mines1 and even from different parts of the same mine1 differ from each other4 ,further confirmation is given by the fact that the country round ,kimberley is remarkable for its ferruginous character1 and iron-saturated soil is popularly regarded as one of the indications of the near presence of diamonds4 ,,graphite ,intermediate between soft carbon and diamond come the graphites4 ,the name graphite is given to a variety of carbon1 generally crystalline1 which in an oxidising mixture of chlorate of potassium and nitric acid forms graphitic oxide4 ,this varies in colour from green to brown or yellow1 or it is almost without colour1 according to the completeness of the reaction4 ,graphites are of varying densities1 from #bj to #cj1 and generally of crystalline aspect4 ,graphite and diamond pass insensibly into one another4 ,hard graphite and soft diamond are near the same specific gravity4 ,the difference appears to be one of pressure at the time of formation4 ,some forms of graphite exhibit the remarkable property by which it is possible to ascertain approximately the temperature at which they were formed1 or to which they have subsequently been exposed4 ,sprouting graphite is a form1 frequently met with in nature1 which on moderate heating swells up to a bulky1 very light mass of amorphous carbon4 ,moissan has found it in blue ground from ,kimberley2 my own results verify his4 ,when obtained by simple elevation of temperature in the arc or the electric furnace graphites do not sprout2 but when they are formed by dissolving carbon in a metal at a high temperature and then allowing the graphite to separate out on cooling1 the sprouting variety appears4 ,the phenomenon of sprouting is easily shown4 ,if a few grains are placed in a test-tube and heated to about #agj ,c41 the grains increase enormously in bulk and fill the tube with a light form of amorphous carbon4 ,the resistance of a graphite to oxidising agents is greater the higher the temperature to which it has previously been exposed4 ,graphites which are easily attacked by a mixture of fuming nitric acid and potassium chlorate are rendered more resistant by strong heat in the electric furnace4 ,i have already signified that there are various degrees of refractoriness to chemical reagents among the different forms of graphite4 ,some dissolve in strong nitric acid2 other forms of graphite require a mixture of highly concentrated nitric acid and potassium chlorate to attack them1 and even with this intensely powerful agent some graphites resist longer than others4 ,m4 ,moissan has shown that the power of resistance to nitric acid and potassium chlorate is in proportion to the temperature at which the graphite was formed1 and with tolerable certainty we can estimate this temperature by the resistance of the specimen of graphite to this reagent4 ,,crystallisation ,the diamond belongs to the isometric system of crystallography2 the prevailing form is octahedral4 ,it frequently occurs with curved faces and edges4 ,twin crystals 7macles7 are not uncommon4 ,diamond crystals are generally perfect on all sides4 ,they seldom show irregular sides or faces by which they were attached to a support1 as do artificial crystals of chemical salts2 another proof that the diamond must have crystallised from a dense liquid4 ,the accompanying illustration 7,fig4 #ad7 shows some of the various crystalline forms of native diamonds4 ,illustration3 ,,fig4 #ad4 ,,crystalline ,,forms ,,of ,,native ,,diamonds4 ,to face p4 #hf4 ,no4 #a4 ,diamond in the form of a hexakis-octahedron 7the forty-eight scalenohedron71 or a solid figure contained by forty-eight scalene triangles4 ,according to ,professor ,maskelyne1 this occurs as a self-existent form only in the diamond4 ,no4 #b4 ,diamond in the form of a hexakis-octahedron and octahedron4 ,from ,sudafrika4 ,no4 #c4 ,diamond in the form of octahedron with intersections4 ,no4 #d4 ,diamond from ,brazil4 ,no4 #e4 ,diamond from ,kimberley4 ,no4 #f4 ,diamond from ,brazil4 ,no1 #g4 ,a macle or twin crystal1 showing its formation from an octahedron with curved edges4 99 99 99 99 99 ,some crystals of diamonds have their surfaces beautifully marked with equilateral triangles1 interlaced and of varying sizes 7,fig4 #ae74 ,under the microscope these markings appear as hollow depressions sharply cut out of the surrounding surface1 and these depressions were supposed by ,gustav ,rose to indicate the probability that the diamonds had at some previous time been exposed to incipient combustion4 ,rose pointed out that similar triangular striations appeared on the surfaces of diamonds burnt before the blowpipe4 ,this experiment ,i have repeated on a clear diamond1 and ,i have satisfied myself that during combustion before the blowpipe1 in the field of a microscope1 the surface is etched with triangular markings different in character from those naturally on crystals 7,fig4 #af74 ,the artificial stri are very irregular1 much smaller1 and massed closer together1 looking as if the diamond during combustion flaked away in triangular chips1 while the markings natural to crystals appear as if produced by the crystallising force as they were being built up4 ,many crystals of chemical compounds appear striated from both these causes4 ,geometrical markings can be produced by eroding the surface of a crystal of alum with water1 and they also occur naturally during crystallisation4 ,illustration3 ,,fig4 #ae4 ,,triangular ,,markings ,,on ,,natural ,,face ,,of ,a ,,diamond ,,crystal4 ,illustration3 ,,fig4 #af4 ,,triangular ,,markings ,,artificially ,,produced ,,on ,a ,,diamond ,,crystal4 ,to face page #hh4 ,,chapter ,,viii ,,physical ,,and ,,chemical ,,properties ,,of ,,the ,,diamond ,i need scarcely say the diamond is almost pure carbon1 and it is the hardest substance in nature4 ,when heated in air or oxygen to a temperature varying from #gfj to #hge ,c41 according to its hardness1 the diamond burns with production of carbonic acid4 ,it leaves an extremely light ash1 sometimes retaining the shape of the crystal1 consisting of iron1 lime1 magnesia1 silica1 and titanium4 ,in boart and carbonado the amount of ash sometimes rises to #d per cent1 but in clear crystallised diamonds it is seldom higher than #jje per cent4 ,by far the largest constituent of the ash is iron4 ,the following table shows the temperatures of combustion in oxygen of different kinds of carbon3 ,c4 ,condensed vapour of carbon #fej ,carbon from sugar1 heated in an electrical furnace #ffj ,artificial graphites1 generally #ffj ,graphite from ordinary cast-iron #fgj ,carbon from blue ground1 of an ochre colour #fij ,carbon from blue ground1 very hard and black #gaj ,diamond1 soft ,brazilian #gfj ,diamond1 hard ,kimberley #ghj ,boart from ,brazil #gij ,boart from ,kimberley #gij ,boart1 very hard1 almost impossible to cut #ijj ,,hardness ,diamonds vary considerably in hardness1 and even different parts of the same crystal differ in their resistance to cutting and grinding4 ,beautifully white diamonds have been found at ,inverel1 ,new ,south ,wales1 and from the rich yield of the mine and the white colour of the stones great things were expected4 ,in the first parcel which came to ,england the stones were found to be so much harder than ,south ,african diamonds that it was at first feared they would be useless except for rock-boring purposes4 ,the difficulty of cutting them disappeared with improved appliances1 and they now are highly prized4 ,the famous ,koh-i-noor1 when being cut into its present form1 showed a notable variation in hardness4 ,in cutting one of the facets near a yellow flaw1 the crystal became harder and harder the further it was cut1 until1 after working the mill for six hours at the usual speed of #bdjj revolutions a minute1 little impression was made4 ,the speed was increased to more than #cjjj1 when the work slowly proceeded4 ,other portions of the stone were found to be comparatively soft1 and became harder as the outside was cut away4 ,the intense hardness of the diamond can be illustrated by the following experiment4 ,on the flattened apex of a conical block of steel place a diamond1 and upon it bring down a second cone of steel4 ,on forcing together the two steel cones by hydraulic pressure the stone is squeezed into the steel blocks without injuring it in the slightest degree4 ,in an experiment ,i made at ,kimberley the pressure gauge showed #fj atmospheres1 and the piston being #cb inches diameter1 the absolute pressure was #caf tons1 equivalent on a diamond of #ab square mm4 surface to #agj tons per square inch of diamond4 ,the use of diamond in glass-cutting ,i need not dwell on4 ,so hard is diamond in comparison to glass1 that a suitable splinter of diamond will plane curls off a glass plate as a carpenter's tool will plane shavings off a deal board4 ,the illustration 7,fig4 #ag7 shows a few diamond-cut glass shavings4 ,,density ,,or ,,specific ,,gravity ,the specific gravity of the diamond varies ordinarily from #cead to #ceah4 ,for comparison1 ,i give in tabular form the specific gravities of the different varieties of carbon and of the minerals found on the sorting tables3 ,,specific ,,gravity4 ,amorphous carbon #ade-agj ,hard gas coke #bcef ,hard graphite #be ,quartzite and granite #bf ,beryl #bg ,mica #bh ,hornblende #cj ,boart #cdg-cdi ,carbonado #cej ,diamond #cead-ceah ,garnet #cg ,corundum #ch ,zircon #dd ,barytes #de ,chrome and titanic iron ore #dg ,magnetite #ej ,there is a substance1 the double nitrate of silver and thallium1 which1 while solid at ordinary temperatures1 liquefies at #ge ,c4 and then has a specific gravity of #de4 ,admixture with water lowers the density to any desired point4 ,if a glass cell is taken containing this liquid diluted to a density of about #cf1 and in it is thrown pieces of the above-named minerals1 all those whose density is lower than #cf will rise to the surface1 while the denser minerals will sink4 ,if now a little water is carefully added with constantly stirring until the density of the liquid is reduced to that of the diamond1 the heterogeneous collection sorts itself into three parts4 ,the graphite1 quartz1 beryl1 mica1 and hornblende rise to the surface2 the garnet1 corundum1 zircons1 etc41 sink to the bottom1 while the diamonds float in the middle of the liquid4 ,with a platinum landing-net ,i can skim off the swimmers and put them into one dish2 with the same net ,i can fish out the diamonds and put them in a second dish1 while by raising a sieve at the bottom ,i can remove the heavy minerals and put them into a third4 ,the accurate separation of diamonds from the heterogeneous mixture can be effected in less time than is taken to describe the experiment4 ,the table shows that diamonds vary somewhat in density among themselves1 between narrow limits4 ,occasionally1 however1 diamonds overpass these figures4 ,here is an illustration4 ,in a test-tube of the same dense liquid are three selected diamonds4 ,one rises to the top1 another floats uncertain where to settle1 rising and falling as the temperature of the sorting liquid is raised or lowered1 whilst the third sinks to the bottom4 ,allowing the liquid to cool a degree or two slightly increases the density and sends all three to the surface4 ,,phosphorescence ,,of ,,diamond ,after exposure for some time to the sun many diamonds glow in a dark room4 ,some diamonds are fluorescent1 appearing milky in sunlight4 ,in a vacuum1 exposed to a high-tension current of electricity1 diamonds phosphoresce of different colours1 most ,south ,african diamonds shining with a bluish light4 ,diamonds from other localities emit bright blue1 apricot1 pale blue1 red1 yellowish green1 orange1 and pale green light4 ,the most phosphorescent diamonds are those which are fluorescent in the sun4 ,one beautiful green diamond in the writer's collection1 when phosphorescing in a good vacuum1 gives almost as much light as a candle1 and you can easily read by its rays4 ,but the time has hardly come when diamonds can be used as domestic illuminants6 ,the emitted light is pale green1 tending to white1 and in its spectrum1 when strong1 can be seen bright lines1 one at about #ecgj in the green1 one at #eacj in the greenish blue1 and one at #ejcj in the blue4 ,a beautiful collection of diamond crystals belonging to ,professor ,maskelyne phosphoresces with nearly all the colours of the rainbow1 the different faces glowing with different shades of colour4 ,diamonds which phosphoresce red generally show the yellow sodium line on a continuous spectrum4 ,in one ,brazilian diamond phosphorescing a reddish-yellow colour ,i detected in its spectrum the citron line characteristic of yttrium4 ,the rays which make the diamond phosphoresce are high in the ultra-violet4 ,to illustrate this phosphorescence under the influence of the ultra-violet rays1 arrange a powerful source of these rays1 and in front expose a design made up of certain minerals1 willemite1 franklinite1 calcite1 etc4--phosphorescing of different colours4 ,their brilliant glow ceases entirely when a thin piece of glass is interposed between them and the ultra-violet lamp4 ,i now draw attention to a strange property of the diamond1 which at first sight might seem to discount the great permanence and unalterability of this stone4 ,it has been ascertained that the cause of phosphorescence is in some way connected with the hammering of the electrons1 violently driven from the negative pole on to the surface of the body under examination1 and so great is the energy of the bombardment1 that impinging on a piece of platinum or even iridium1 the metal will actually melt4 ,when the diamond is thus bombarded in a radiant matter tube the result is startling4 ,it not only phosphoresces1 but becomes discoloured1 and in course of time becomes black on the surface4 ,some diamonds blacken in the course of a few minutes1 while others require an hour or more to discolour4 ,this blackening is only superficial1 and although no ordinary means of cleaning will remove the discolouration1 it goes at once when the stone is polished with diamond powder4 ,ordinary oxidising reagents have little or no effect in restoring the colour4 ,illustration3 ,,fig4 #ag4 ,,diamond-,,cut ,,glass ,,and ,,shavings4 ,illustration3 ,,fig4 #ah4 ,,diamonds ,,in ,r,,ntgen ,,rays4 ,a4 ,,black ,,diamond ,,in ,,gold ,,frame4 ,b4 ,,pink ,,delhi ,,diamond4 ,c4 ,,paste ,,imitation ,,of ,b4 ,to face p4 #ih4 ,the superficial dark coating on a diamond after exposure to molecular bombardment ,i have proved to be graphite4 ,m4 ,moissan has shown that this graphite1 on account of its great resistance to oxidising reagents1 cannot have been formed at a lower temperature than #cfjj ,c4 ,it is thus manifest that the bombarding electrons1 striking the diamond with enormous velocity1 raise the superficial layer to the temperature of the electric arc and turn it into graphite1 whilst the mass of diamond and its conductivity to heat are sufficient to keep down the general temperature to such a point that the tube appears scarcely more than warm to the touch4 ,a similar action occurs with silver1 the superficial layers of which can be raised to a red heat without the whole mass becoming more than warm4 ,,conversion ,,of ,,diamond ,,into ,,graphite ,although we cannot convert graphite into diamond1 we can change the diamond into graphite4 ,a clear crystal of diamond is placed between two carbon poles1 and the poles with intervening diamond are brought together and an arc formed between4 ,the temperature of the diamond rapidly rises1 and when it approaches #cfjj ,c41 the vaporising point of carbon1 it breaks down1 swells1 and changes into black and valueless graphite4 ,,tribo-,,luminescence ,a few minerals give out light when rubbed4 ,in the year #affc the ,hon4 ,robert ,boyle read a paper before the ,royal ,society1 in which he described several experiments made with a diamond which markedly showed tribo-luminescence4 ,as specimens of tribo-luminescent bodies ,i may instance sphalerite 7sulphide of zinc71 and an artificial sphalerite1 which is even more responsive to friction than the native sulphide4#f ,mrs4 ,kunz1 wife of the well-known ,new ,york mineralogist1 possesses1 perhaps1 the most remarkable of all phosphorescing diamonds4 ,this prodigy diamond will phosphoresce in the dark for some minutes after being exposed to a small pocket electric light1 and if rubbed on a piece of cloth a long streak of phosphorescence appears4 ,,absorption ,,spectrum ,,of ,,diamond ,on passing a ray of light through a diamond and examining it in a spectroscope1 ,walter has found in all colourless brilliants of over #a carat in weight an absorption band at wave-length #daee 7violet74 ,he ascribes this band to an impurity and suggests it may possibly be due to samarium4 ,three other fainter lines were detected in the ultra-violet by means of photography4 ,,refractivity ,but it is not the hardness of the diamond so much as its optical qualities that make it so highly prized4 ,it is one of the most refracting substances in nature1 and it also has the highest reflecting properties4 ,in the cutting of diamonds advantage is taken of these qualities4 ,when cut as a brilliant the facets on the lower side are inclined so that light falls on them at an angle of #bd #ac1 at which angle all the incident light is totally reflected4 ,a well-cut brilliant should appear opaque by transmitted light except at a small spot in the middle where the table and culet are opposite4 ,all the light falling on the front of the stone is reflected from the facets1 and the light passing into the diamond is reflected from the interior surfaces and refracted into colours when it passes out into the air1 giving rise to the lightnings1 the effulgence1 and coruscations for which the diamond is supreme above all other gems4 ,the following table gives the refractive indices of diamonds and other bodies3 ,,refractive ,,indices ,,for ,,the ,d ,,line ,chromate of lead #bej-big ,diamond #bdg-bge ,phosphorus #bbb ,sulphur #bab ,ruby #agh ,thallium glass #age ,iceland spar #afe ,topaz #afa ,beryl #afj ,emerald #aei ,flint glass #aeh ,quartz #aee ,canada balsam #aec ,crown glass #aec ,fluor-spar #add ,ice #aca ,in vain ,i have searched for a liquid of the same refraction as diamond4 ,such a liquid would be invaluable to the merchant1 as on immersing a stone the clear body would absolutely disappear1 leaving in all their ugliness the flaws and black specks so frequently seen even in the best stones4 ,,the ,,diamond ,,and ,,polarised ,,light ,having no double refraction1 the diamond should not act on polarised light4 ,but as is well known1 if a transparent body which does not so act is submitted to strain of an irregular character it becomes doubly refracting1 and in the polariscope reveals the existence of the strain by brilliant colours arranged in a more or less defined pattern1 according to the state of tension in which the crystal exists4 ,i have examined many hundred diamond crystals under polarised light1 and with few exceptions the colours show how great is the strain to which some of them are exposed4 ,on rotating the polariser1 the black cross most frequently seen revolves round a particular point in the inside of the crystal2 on examining this point with a high power we sometimes see a slight flaw1 more rarely a minute cavity4 ,the cavity is filled with gas at enormous pressure1 and the strain is set up in the stone by the effort of the gas to escape4 ,i have already said that the great ,cullinan diamond by this means revealed a state of considerable internal stress and strain4 ,so great is this strain of internal tension that it is not uncommon for a diamond to explode soon after it reaches the surface1 and some have been known to burst in the pockets of the miners or when held in the warm hand4 ,large crystals are more liable to burst than smaller pieces4 ,valuable stones have been destroyed in this way1 and it is whispered that cunning dealers are not averse to allowing responsible clients to handle or carry in their warm pockets large crystals fresh from the mine4 ,by way of safeguard against explosion some dealers imbed large diamonds in raw potato to ensure safe transit to ,england4 ,the anomalous action which many diamonds exert on polarised light is not such as can be induced by heat1 but it can easily be conferred on diamonds by pressure1 showing that the strain has not been produced by sudden cooling1 but by sudden lowering of pressure4 ,the illustration of this peculiarity is not only difficult1 but sometimes exceedingly costly--difficult because it is necessary to arrange for projecting on the screen the image of a diamond crystal between the jaws of a hydraulic press1 the illuminating light having to pass through delicate optical polarising apparatus--and costly because only perfectly clear crystals can be used1 and crystals of this character sometimes fly to pieces as the pressure rises4 ,at first no colour is seen on the screen1 the crystal not being birefringent4 ,a movement of the handle of the press1 however1 gives the crystal a pinch1 instantly responded to by the colours on the screen1 showing the production of double refraction4 ,another movement of the handle brightens the colours1 and a third may strain the crystal beyond its power of resistance1 when the crystal flies to pieces4 ,,the ,,diamond ,,and ,r,,ntgen ,,rays ,the diamond is remarkable in another respect4 ,it is extremely transparent to the ,rntgen rays1 whereas highly refracting glass1 used in imitation diamonds1 is almost perfectly opaque to the rays4 ,i exposed for a few seconds over a photographic plate to the ,x-rays the large ,delhi diamond of a rose-pink colour weighing #ca carats1 a black diamond weighing #bc carats1 and a glass imitation of the pink diamond 7,fig4 #ah74 ,on development the impression where the diamond obscured the rays was found to be strong1 showing that most rays passed through1 while the glass was practically opaque4 ,by this means imitation diamonds can readily be distinguished from true gems4 ,,action ,,of ,,radium ,,on ,,diamond ,the -rays from radium having like properties to the stream of negative electrons in a radiant matter tube1 it was of interest to ascertain if they would exert a like difference on diamond4 ,the diamond glows under the influence of the -radiations1 and crushed diamond cemented to a piece of card or metal makes an excellent screen in a spinthariscope--almost as good as zinc sulphide4 ,some colourless crystals of diamond were imbedded in radium bromide and kept undisturbed for more than twelve months4 ,at the end of that time they were examined4 ,the radium had caused them to assume a bluish-green colour1 and their value as 8fancy stones0 had been increased4 ,this colour is persistent and penetrates below the surface4 ,it is unaffected by long-continued heating in strong nitric acid and potassium chlorate1 and is not discharged by heating to redness4 ,to find out if this prolonged contact with radium had communicated to the diamond any radio-active properties1 six diamonds were put on a photographic plate and kept in the dark for a few hours4 ,all showed radio-activity by darkening the sensitive plate1 some being more-active than others4 ,like the green tint1 the radio-activity persists after drastic treatment4 ,to me this proves that radio-activity does not merely consist in the adhesion of electrons or emanations given off by radium to the surface of an adjacent body1 but the property is one involving layers below the surface1 and like the alteration of tint1 is probably closely connected with the intense molecular excitement the stone had experienced during its twelve months' burial in radium bromide4 ,a diamond that had been coloured by radium1 and had acquired strong radio-active properties1 was slowly heated to dull redness in a dark room4 ,just before visibility a faint phosphorescence spread over the stone4 ,on cooling and examining the diamond it was found that neither the colour nor the radio-activity had suffered appreciably4 ,,boiling- ,,and ,,melting-,,point ,,of ,,carbon ,on the average the critical point of a substance is #ae times its absolute boiling-point4 ,therefore the critical point of carbon should be about #ehjj ,ab4 ,but the absolute critical temperature divided by the critical pressure is for all the elements so far examined never less than #be2 this being about the value ,sir ,james ,dewar finds for hydrogen4 ,so that1 accepting this1 we get the maximum critical pressure as follows1 viz4 #bcbj atmospheres3 7#ehjj ,ab47_/,cr,p #b4e1 or ,cr,p 7#ehjj ,ab47_/#b4e1 or #bcbj atmospheres4 ,carbon and arsenic are the only two elements that have a melting-point above the boiling-point2 and among compounds carbonic acid and fluoride of silicium are the only other bodies with similar properties4 ,now the melting-point of arsenic is about #ab times its absolute boiling-point4 ,with carbonic acid and fluoride of silicium the melting-points are about #aa times their boiling-points4 ,applying these ratios to carbon1 we find that its melting-point would be about #ddjj4 ,therefore1 assuming the following data3 ,boiling-point #chgj ,ab4 ,melting-point #ddjj ,critical temperature #ehjj ,critical pressure #bcbj ,ats4 the ,rankine or ,van der ,waals formula1 calculated from the boiling-point and critical data1 would be as follows3 log4 ,p #ajaa - #ciabj_/,t1 and this gives for a temperature of #ddjj ,ab4 a pressure of #aff ,ats4 as the melting-point pressure4 ,the results of the formula are given in the form of a table3 ,temperature ,pressure ,ab4 ,ats4 #chgj #ajj ,boiling-point4 #djjj #bad #dbjj #fbe #ddjj #aff ,melting-point4 #dfjj #djd #dhjj #iab #ejjj #aic #ebjj #chf #edjj #gce #efjj #accj #ehjj #bcbj ,critical point 7#ae tons per square inch74 ,illustration3 ,,fig4 #ai4 ,,curve ,,of ,,vapour ,,pressure ,,of ,,carbon ,if1 then1 we may reason from these rough estimates1 above a temperature of #ehjj ,ab4 no amount of pressure will cause carbon vapour to assume liquid form1 whilst at #ddjj ,ab4 a pressure of above #ag atmospheres would suffice to liquefy some of it4 ,between these extremes the curve of vapour pressure is assumed to be logarithmic1 as represented in the accompanying diagram4 ,the constant #ciabj which occurs in the logarithmic formula enables us to calculate the latent heat of evaporation4 ,if we assume the vapour density to be normal1 or the molecule in vapour as ,c#b1 then the heat of volatilisation of #ab grms4 of carbon would be #ij1jjj calories2 or1 if the vapour is a condensed molecule like ,c#f1 then the #ab grms4 would need #cj1jjj calories4 ,in the latter case the evaporation of #a grm4 of carbon would require #bejj calories1 whereas a substance like zinc needs only about #djj calories4 ,,chapter ,,ix ,,genesis ,,of ,,the ,,diamond ,speculations as to the probable origin of the diamond have been greatly forwarded by patient research1 and particularly by improved means of obtaining high temperatures1 an advance we owe principally to the researches of the late ,professor ,moissan4 ,until recent years carbon was considered absolutely non-volatile and infusible2 but the enormous temperatures placed at the disposal of experimentalists by the introduction of electricity show that1 instead of breaking rules1 carbon obeys the same laws that govern other bodies4 ,it volatilises at the ordinary pressure at a temperature of about #cfjj ,c41 and passes from the solid to the gaseous state without liquefying4 ,it has been found that other bodies1 such as arsenic1 which volatilise without liquefying at the ordinary pressure1 will easily liquefy if pressure is added to temperature4 ,it naturally follows that if along with the requisite temperature sufficient pressure is applied1 liquefaction of carbon will take place1 when on cooling it will crystallise4 ,but carbon at high temperatures is a most energetic chemical agent1 and if it can get hold of oxygen from the atmosphere or any compound containing it1 it will oxidise and fly off in the form of carbonic acid4 ,heat and pressure therefore are of no avail unless the carbon can be kept inert4 ,it has long been known that iron1 when melted1 dissolves carbon1 and on cooling liberates it in the form of graphite4 ,moissan discovered that several other metals1 especially silver1 have similar properties2 but iron is the best solvent for carbon4 ,the quantity of carbon entering into solution increases with the temperature4 ,illustration3 ,,fig4 #bj4 ,,moissan',s ,,electric ,,furnace4 ,to face p4 #aaf4 ,for the artificial manufacture of diamond the first necessity is to select pure iron--free from sulphur1 silicon1 phosphorus1 etc4--and to pack it in a carbon crucible with pure charcoal from sugar4 ,the crucible is then put into the body of the electric furnace and a powerful arc formed close above it between carbon poles1 utilising a current of #gjj ampres at #dj volts pressure 7,fig4 #bj74 ,the iron rapidly melts and saturates itself with carbon4 ,after a few minutes' heating to a temperature above #djjj ,c4--a temperature at which the iron melts like wax and volatilises in clouds--the current is stopped and the dazzling fiery crucible is plunged beneath the surface of cold water1 where it is held till it sinks below a red heat4 ,as is well known1 iron increases in volume at the moment of passing from the liquid to the solid state4 ,the sudden cooling solidifies the outer layer of iron and holds the inner molten mass in a tight grip4 ,the expansion of the inner liquid on solidifying produces an enormous pressure1 and under the stress of this pressure the dissolved carbon separates out in transparent forms--minutely microscopic1 it is true--all the same veritable diamonds1 with crystalline form and appearance1 colour1 hardness1 and action on light1 the same as the natural gem4 ,now commences the tedious part of the process4 ,the metallic ingot is attacked with hot nitro-hydrochloric acid until no more iron is dissolved4 ,the bulky residue consists chiefly of graphite1 together with translucent chestnut-coloured flakes of carbon1 black opaque carbon of a density of from #cj to #ce and hard as diamonds--black diamonds or carbonado1 in fact--and a small portion of transparent1 colourless diamonds showing crystalline structure4 ,besides these there may be carbide of silicon and corundum1 arising from impurities in the materials employed4 ,the residue is first heated for some hours with strong sulphuric acid at the boiling-point1 with the cautious addition of powdered nitre4 ,it is then well washed and for two days allowed to soak in strong hydrofluoric acid in cold1 then in boiling acid4 ,after this treatment the soft graphite disappears1 and most1 if not all1 the silicon compounds have been destroyed4 ,hot sulphuric acid is again applied to destroy the fluorides1 and the residue1 well washed1 is attacked with a mixture of the strongest nitric acid and powdered potassium chlorate1 kept warm--but not above #fj ,c41 to avoid explosions4 ,this treatment must be repeated six or eight times1 when all the hard graphite will gradually be dissolved and little else left but graphitic oxide1 diamond1 and the harder carbonado and boart4 ,the residue is fused for an hour in fluorhydrate or fluoride of potassium1 then boiled out in water and again heated in sulphuric acid4 ,the well-washed grains which resist this energetic treatment are dried1 carefully deposited on a slide1 and examined under the microscope4 ,along with numerous pieces of black diamond are seen transparent1 colourless pieces1 some amorphous1 others with a crystalline appearance4 ,fig4 #ba ,b shows one of these crystalline fragments4 ,although many fragments of crystals occur1 it is remarkable ,i have never seen a complete crystal4 ,all appear shattered1 as if on being liberated from the intense pressure under which they were formed they burst asunder4 ,i have singular evidence of this phenomenon4 ,a fine piece of artificial diamond1 carefully mounted by me on a microscopic slide1 exploded during the night and covered the slide with fragments4 ,moissan's crystals of artificial diamond sometimes broke a few weeks after their preparation1 and some of the diamonds which cracked weeks or even months after their preparation showed fissures covered with minute cubes4 ,i have explained that this bursting paroxysm is not unknown at the ,kimberley mines4 ,so far1 all such artificial diamonds are microscopic4 ,the largest artificial diamond is less than one millimetre across4 ,illustration3 ,,fig4 #ba4 ,,artificial ,,diamond ,,made ,,by ,,the ,,author ,,from ,,molten ,,iron4 ,illustration3 ,,fig4 #bb4 ,,moissan',s ,,artificial ,,diamonds4 ,to face p4 #abj4 ,these laboratory diamonds burn in the air before the blowpipe to carbonic acid4 ,in lustre1 crystalline form1 optical properties1 density1 and hardness they are identical with the natural stone4 ,in several cases ,moissan separated ten to fifteen microscopic diamonds from a single ingot4 ,the larger of these are about #jge mm4 long1 the octahedra being #jb mm4 ,the accompanying illustrations 7,fig4 #bb7 are copied from drawings in ,moissan's book ,le ,four ,electrique4 ,along with carbon1 molten iron dissolves other bodies which possess tinctorial powers4 ,we know of blue1 green1 pink1 yellow1 and orange diamonds4 ,one batch of iron might contain an impurity colouring the stones blue1 another lot would tend towards the formation of pink stones1 another of green1 and so on4 ,cobalt1 nickel1 chromium1 and manganese1 all metals present in the blue ground1 would produce these colours4 ,a ,,new ,,formation ,,of ,,diamond ,i have long speculated as to the possibility of obtaining artificially such pressures and temperatures as would fulfil the above conditions4 ,in their researches on the gases from fired gunpowder and cordite1 ,sir ,frederick ,abel and ,sir ,andrew ,noble obtained in closed steel cylinders pressures as great as #ie tons to the square inch1 and temperatures as high as #djjj ,c4 ,according to a paper recently communicated to the ,royal ,society1 ,sir ,andrew ,noble1 exploding cordite in closed vessels1 has obtained a pressure of #hjjj atmospheres1 or #ej tons per square inch1 with a temperature reaching in all probability #edjj ,ab4 ,here1 then1 we have conditions favourable for the liquefaction of carbon1 and were the time of explosion sufficient to allow the reactions to take place1 we should certainly expect to get the liquid carbon to solidify in the crystalline state4#g ,by the kindness of ,sir ,andrew ,noble ,i have been enabled to work upon some of the residues obtained in closed vessels after explosions1 and ,i have submitted them to the same treatment that the granulated iron had gone through4 ,after weeks of patient toil ,i removed the amorphous carbon1 the graphite1 the silica1#h and other constituents of the ash of cordite1 and obtained a residue among which1 under the microscope1 crystalline particles could be distinguished4 ,some of these particles1 from their crystalline appearance and double refraction1 were silicon carbide2 others were probably diamonds4 ,the whole residue was dried and fused at a good red heat in an excess of potassium bifluoride1 to which was added1 during fusion1 #e per cent of nitre4 7,previous experiments had shown me that this mixture readily attacked and dissolved silicon carbide2 unfortunately it also attacks diamond to a slight degree47 ,all the operations of washing and acid treatment were performed in a large platinum crucible by decantation 7except the preliminary attack with nitric acid and potassium chlorate1 when a hard glass vessel was used72 the final result was washed into a shallow watch-glass and the selection made under the microscope4 ,the residue1 after thorough washing and then heating in fuming sulphuric acid1 was washed1 and the largest crystalline particles picked out and mounted4 ,from the treatment the residual crystals had undergone1 chemists will agree with me that diamonds only could stand such an ordeal2 on submitting them to skilled crystallographic authorities my opinion is confirmed4 ,speaking of the largest crystal1 one eminent authority calls it 8a diamond showing octahedral planes with dark boundaries due to high refracting index40 ,after careful examination1 another authority writes of the same crystal diamond1 8,i think one may safely say that the position and angles of its faces1 and of its cleavages1 the absence of birefringence1 and the high refractive index are all compatible with the properties of the diamond crystallising in the form of an octahedron4 ,others of the remaining crystals1 which show a similar high refractive index1 appeared to me to present the same features40 ,it would have been more conclusive had ,i been able to get further evidence as to the density and hardness of the crystals2 but from what ,i have already said ,i think there is no doubt that in these closed vessel explosions we have another method of producing the diamond artificially4 ,,chapter ,x ,,the ,,natural ,,formation ,,of ,,the ,,diamond ,an hypothesis is of little value if it only elucidates half a problem4 ,let us see how far we can follow out the ferric hypothesis to explain the volcanic pipes4 ,in the first place we must remember these so-called volcanic vents are admittedly not filled with the eruptive rocks1 scoriaceous fragments1 etc41 constituting the ordinary contents of volcanic ducts4 ,certain artificial diamonds present the appearance of an elongated drop4 ,i have seen diamonds which have exactly the appearance of drops of liquid separated in a pasty condition and crystallised on cooling4 ,diamonds are sometimes found with little appearance of crystallisation1 but with rounded forms similar to those which a liquid might assume if kept in the midst of another liquid with which it would not mix4 ,other drops of liquid carbon retained for sufficient time above their melting-point would coalesce with adjacent drops1 and on slow cooling would separate in the form of large perfect crystals4 ,two drops1 joining after incipient crystallisation1 might assume the not uncommon form of interpenetrating twin crystals4 ,many circumstances point to the conclusion that the diamond of the chemist and the diamond of the mine are strangely akin as to origin4 ,it is evident that the diamond has not been formed in situ in the blue ground4 ,the genesis must have taken place at vast depths under enormous pressure4 ,the explosion of large diamonds on coming to the surface shows extreme tension4 ,more diamonds are found in fragments and splinters than in perfect crystals2 and it is noteworthy that although these splinters and fragments must be derived from the breaking up of a large crystal1 yet in only one instance have pieces been found which could be fitted together1 and these occurred at different levels4 ,does not this fact point to the conclusion that the blue ground is not their true matrix8 ,nature does not make fragments of crystals4 ,as the edges of the crystals are still sharp and unabraded1 the locus of formation cannot have been very distant from the present sites4 ,there were probably many sites of crystallisation differing in place and time1 or we should not see such distinctive characters in the gems from different mines1 nor indeed in the diamonds from different parts of the same mine4 ,i start with the reasonable supposition that at a sufficient depth#i there were masses of molten iron at great pressure and high temperature1 holding carbon in solution1 ready to crystallise out on cooling4 ,far back in time the cooling from above caused cracks in superjacent strata through which water#aj found its way4 ,on reaching the incandescent iron the water would be converted into gas1 and this gas would rapidly disintegrate and erode the channels through which it passed1 grooving a passage more and more vertical in the necessity to find the quickest vent to the surface4 ,but steam in the presence of molten or even red-hot iron liberates large volumes of hydrogen gas1 together with less quantities of hydrocarbons#aa of all kinds--liquid1 gaseous1 and solid4 ,erosion commenced by steam would be continued by the other gases2 it would be easy for pipes1 large as any found in ,south ,africa1 to be scored out in this manner4 ,sir ,andrew ,noble has shown that when the screw stopper of his steel cylinders in which gunpowder explodes under pressure is not absolutely perfect1 gas escapes with a rush so overpowering and a temperature so high as to score a wide channel in the metal4 ,to illustrate my argument ,sir ,andrew ,noble has been kind enough to try a special experiment4 ,through a cylinder of granite he drilled a hole #jb inch diameter1 the size of a small vent4 ,this was made the stopper of an explosion chamber1 in which a quantity of cordite was fired1 the gases escaping through the granite vent4 ,the pressure was about #aejj atmospheres and the whole time of escape was less than half a second4 ,the erosion produced by the escaping gases and by the heat of friction scored out a channel more than half an inch diameter and melted the granite along the course4 ,if steel and granite are thus vulnerable at comparatively moderate gaseous pressure1 it is easy to imagine the destructive upburst of hydrogen and water-gas1 grooving for itself a channel in the diabase and quartzite1 tearing fragments from resisting rocks1 covering the country with debris1 and finally1 at the subsidence of the great rush1 filling the self-made pipe with a water-borne magma in which rocks1 minerals1 iron oxide1 shale1 petroleum1 and diamonds are violently churned in a veritable witch's cauldron6 ,as the heat abated the water vapour would gradually give place to hot water1 which1 forced through the magma1 would change some of the mineral fragments into the existing forms of to-day4 ,each outbreak would form a dome-shaped hill2 the eroding agency of water and ice would plane these eminences until all traces of the original pipes were lost4 ,actions such as ,i have described need not have taken place simultaneously4 ,as there must have been many molten masses of iron with variable contents of carbon1 different kinds of colouring matter1 solidifying with varying degrees of rapidity1 and coming in contact with water at intervals throughout long periods of geological time--so must there have been many outbursts and upheavals1 giving rise to pipes containing diamonds4 ,and these diamonds1 by sparseness of distribution1 crystalline character1 difference of tint1 purity of colour1 varying hardness1 brittleness1 and state of tension1 have the story of their origin impressed upon them1 engraved by natural forces--a story which future generations of scientific men may be able to interpret with greater precision than is possible to-day4 ,,chapter ,,xi ,,meteoric ,,diamonds ,sensational as is the story of the diamond industry in ,south ,africa1 quite another aspect fixes the attention of the chemist4 ,the diamonds come out of the mines1 but how did they get in8 ,how were they formed8 ,what is their origin8 ,gardner ,williams1 who knows more about diamonds than any man living1 is little inclined to indulge in speculation4 ,in his fascinating book he frankly says3 8,i have been frequently asked1 #8,what is your theory of the original crystallisation of the diamond8' and the answer has always been1 #8,i have none2 for after seventeen years of thoughtful study1 coupled with practical research1 ,i find that it is easier to 8drive a coach and four0 through most theories that have been propounded than to suggest one which would be based on any non-assailable data4' ,all that can be said is that in some unknown manner carbon1 which existed deep down in the internal regions of the earth1 was changed from its black and uninviting appearance to the most beautiful gem which ever saw the light of day40 ,another diamond theory appeals to the imagination4 ,it is said the diamond is a gift from ,heaven1 conveyed to earth in meteoric showers4 ,the suggestion1 ,i believe1 was first broached by ,a4 ,meydenbauer1#ab who says1 8,the diamond can only be of cosmic origin1 having fallen as a meteorite at later periods of the earth's formation4 ,the available localities of the diamond contain the residues of not very compact meteoric masses which may1 perhaps1 have fallen in prehistoric ages1 and which have penetrated more or less deeply1 according to the more or less resistant character of the surface where they fell4 ,their remains are crumbling away on exposure to the air and sun1 and the rain has long ago washed away all prominent masses4 ,the enclosed diamonds have remained scattered in the river beds1 while the fine light matrix has been swept away40 ,according to this hypothesis1 the so-called volcanic pipes are simply holes bored in the solid earth by the impact of monstrous meteors--the larger masses boring the holes1 while the smaller masses1 disintegrating in their fall1 distributed diamonds broadcast4 ,bizarre as such a theory appears1 ,i am bound to say there are many circumstances which show that the notion of the heavens raining diamonds is not impossible4 ,the most striking confirmation of the meteoric theory comes from ,arizona4 ,here1 on a broad open plain1 over an area about five miles in diameter1 have been scattered one or two thousand masses of metallic iron1 the fragments varying in weight from half a ton to a fraction of an ounce4 ,there is no doubt these masses formed part of a meteoric shower1 although no record exists as to when the fall took place4 ,curiously enough1 near the centre1 where most of the meteorites have been found1 is a crater with raised edges three-quarters of a mile in diameter and about #fjj feet deep1 bearing exactly the appearance which would be produced had a mighty mass of iron struck the ground and buried itself deep under the surface4 ,altogether1 ten tons of this iron have been collected1 and specimens of the ,canyon ,diablo meteorite are in most collectors' cabinets4 ,an ardent mineralogist--the late ,dr4 ,foote--cutting a section of this meteorite1 found the tools were injured by something vastly harder than metallic iron4 ,he examined the specimen chemically1 and soon after announced to the scientific world that the ,canyon ,diablo meteorite contained black and transparent diamonds4 ,this startling discovery was afterwards verified by ,professors ,moissan and ,friedel1 and ,moissan1 working on #ahc kilogrammes of the ,canyon ,diablo meteorite1 has recently found smooth black diamonds and transparent diamonds in the form of octahedra with rounded edges1 together with green1 hexagonal crystals of carbon silicide4 ,the presence of carbon silicide in the meteorite shows that it must at some time have experienced the temperature of the electric furnace4 ,since this revelation the search for diamonds in meteorites has occupied the attention of chemists all over the world4 ,fig4 #bc ,a1 ,c1 and ,d1 are reproductions of photographs of true diamonds ,i myself have extracted from the ,canyon ,diablo meteorite4 ,illustration3 ,,fig4 #bc4 ,,diamonds ,,from ,,canyon ,,diablo ,,meteorite4 ,to face p4 #ach4 ,under atmospheric influences the iron would rapidly oxidise and rust away1 colouring the adjacent soil with red oxide of iron4 ,the meteoric diamonds would be unaffected and left on the surface of the soil1 to be found haphazard when oxidation had removed the last proof of their celestial origin4 ,that there are still lumps of iron left at ,arizona is merely due to the extreme dryness of the climate and the comparatively short time that the iron has been on our planet4 ,we are here witnesses to the course of an event which may have happened in geologic times anywhere on the earth's surface4 ,although in ,arizona diamonds have fallen from the skies1 confounding our senses1 this descent of precious stones is what may be called a freak of nature rather than a normal occurrence4 ,to the modern student of science there is no great difference between the composition of our earth and that of extra-terrestrial masses4 ,the mineral peridot is a constant extra-terrestrial visitor1 present in most meteorites4 ,and yet no one doubts that peridot is also a true constituent of rocks formed on this earth4 ,the spectroscope reveals that the elementary composition of the stars and the earth are pretty much the same2 and the spectroscope also shows that meteorites have as much of earth as of heaven in their composition4 ,indeed1 not only are the selfsame elements present in meteorites1 but they are combined in the same way to form the same minerals as in the crust of the earth4 ,it is certain from observations ,i have made1 corroborated by experience gained in the laboratory1 that iron at a high temperature and under great pressure--conditions existent at great depths below the surface of the earth--acts as the long-sought solvent for carbon1 and will allow it to crystallise out in the form of diamond4 ,but it is also certain1 from the evidence afforded by the ,arizona and other meteorites1 that similar conditions have existed among bodies in space1 and that on more than one occasion a meteorite freighted with jewels has fallen as a star from the sky4 ,,index ,able1 ,sir ,f41 closed vessel experiments1 #abb ,absorption spectrum of diamond1 #aja ,aliwal ,north1 #f ,alluvial deposits of diamonds1 #i ,amygdaloidal trap1 #aj ,arizona meteor1 #acf ,arkansas1 diamonds in1 #b ,ash of diamond1 #hb1 #hi ,augite1 #bj ,automatic diamond collector1 #ef ,barytes1 #ga -- density of1 #ic ,basalt1 #ae ,basutos1 #ab1 #ci ,bechuanas1 #ab1 #ci ,beryl1 density of1 #ic -- refractive index of1 #ajc ,biotite1 #bj ,blackening of diamonds1 #ih ,blue ground1 #aj1 #dg -- -- diamantiferous1 #ah1 #ai ,boart1 #ha1 -- combustion temperature of1 #ij -- density of1 #ic ,boiling-point of carbon1 #aaj ,bonney1 ,rev4 ,professor1 #fg ,boyle on the diamond1 #ajj ,brazil1 diamonds in1 #d ,breakwater1 ,cape ,town1 #cf ,breccia1 diamantiferous1 #ai ,brilliant cut diamond1 #ajb ,british ,association in ,south ,africa1 #g ,british ,guiana1 diamonds in1 #d ,bronzite1 #bj1 #ga -- hydrated1 #ai ,bultfontein ,mine1 #ad -- -- characteristics of diamond from1 #fd ,bursting of diamonds1 #aje ,calcite1 #bj1 #ig ,california1 diamonds in1 #c ,canada balsam1 refractive index of1 #ajc ,canyon ,diablo meteorite1 #acf ,cape ,colony1 #e ,cape ,town1 #e ,carat1 equivalent in grains1 #fi ,carbon1 boiling and melting point of1 #aaj -- combustion temperature of1 #ij -- critical point of1 #aaj -- density of1 #ic -- dissolved in iron1 #aaf -- volatilisation of1 #aae ,carbonado1 #ha -- density of1 #ic ,characteristics of diamonds from the different mines1 #fd ,chemical properties of diamond1 #hi ,chromate of lead1 refractive index of1 #ajc ,chrome diopside1 #ga -- iron1 #bj -- -- ore1 #ga -- -- -- density of1 #ic ,chromite1 #bj ,classification of rough diamonds1 #gc ,cleavage of diamonds1 #gh ,coke1 density of1 #ic ,colesberg ,kopje1 #bf ,collecting the gems1 #ee ,coloured diamonds1 #fb1 #hb ,combustion of diamond1 #hi -- temperatures of diamond1 boart1 graphite1 and carbon1 #ij 8,comet0 crushers1 #di ,compound system1 #cf1 #cg ,concentrating and washing machinery1 #di ,convict labourers1 #ga ,cordite1 diamond from explosion of1 #abc ,corundum1 #bj -- density of1 #ic ,cradock1 #f ,craters or pipes1 #ah ,crown glass1 refractive index of1 #ajc ,crusher1 8,comet10 #di ,crystallisation of diamond1 #hf ,crystals1 octahedra1 of diamond1 #fc1 #hf ,cullinan diamond1 #ae1 #gf1 #hj1 #ajd ,dallas1 ,captain1 #dj ,de ,beers ,consolidated ,mines1 #g1 #cc -- -- floors at ,kenilworth1 #dg -- -- ,mine1 #ad1 #bd1 #cd -- -- -- characteristics of diamonds from1 #fd -- -- strong-room1 #gd ,delhi diamond1 #ajg ,density of diamond1 #eg1 #ic -- of graphite1 #hc1 #ic -- of stones accompanying diamond1 #gj1 #ga1 #ic1 #ie ,depositing floors1 #df ,dewar1 ,sir ,j41 conversion of diamond into graphite1 #abc ,diabase1 olivine1 #af ,diallage1 #bj ,diamond1 absorption spectrum of1 #aja -- and polarised light1 #ajd -- a new formation of1 #abb -- ash of1 #hb1 #hi -- collector1 automatic1 #ef -- combustion of1 #hi -- -- temperature of1 #ij -- converted into graphite1 #ajj -- density of1 #eg1 #ic -- etched by burning1 #hh -- explosion of1 #abj -- genesis of the1 #aae -- in meteors1 #acd -- in ,rntgen rays1 #ajg -- matrix of1 #fg -- natural formation of1 #abg -- ,office at ,kimberley1 #gc -- physical and chemical properties of1 #hi -- pipes or craters1 #ah -- radio-activity of1 #aji -- refractive index of1 #ajc -- ,trade ,act1 #cf -- triangular markings on1 #hg -- tribo-luminescence of1 #ajj ,diamonds1 coloured or fancy1 #fb1 #hb -- ,maskelyne on1 #a -- noteworthy1 #gf -- phosphorescence of1 #if -- produced1 weight1 value of1 #ce -- yield of1 from ,de ,beers1 #fj ,drift1 diamonds from the1 #ab ,duke of ,tuscany diamond1 #hj ,dutch boart1 or zircon1 #ei ,dutoitspan ,mine1 #ad1 #bc -- -- characteristics of diamonds from1 #fd ,eclogite1 #bj -- containing diamonds1 #fg ,electrons1 bombardment by1 #ih ,emerald1 refractive index of1 #ajc ,empress ,eugenie diamond1 #hj ,enstatite1 #bj ,explosion of diamonds1 #abj ,excelsior diamond1 #hj ,fancy stones1 #fb ,fingoes1 #ci ,flint glass1 refractive index of1 #ajc 8,floating ,reef10 #ba ,floors1 depositing1 #df ,fluor-spar1 refractive index of1 #ajc ,formation1 new1 of diamond1 #abb ,fort ,beaufort1 #f ,franklinite1 #ig ,frank ,smith ,mine1 #ae -- -- -- characteristics of diamonds from1 #ff ,fraserburg1 #f ,garnet1 #bj1 #gj -- density of1 #ic ,genesis of the diamond1 #aae 8,golden fancies10 #fe ,granite1 #ah -- density of1 #ic ,graphite1 #ha1 #hc -- combustion temperature of1 #ij -- conversion of diamond into1 #ajj -- density of1 #ic -- diamonds coated with1 #ii ,graphitic oxide1 #hc1 #ic ,grease1 collecting diamonds by aid of1 #eg ,hard blue ground1 #dg ,hardness of diamond1 #ij ,haulage system1 #df ,hexakis-octahedron crystal1 #hf ,hope blue diamond1 the1 #hj ,hornblende1 #ga -- density of1 #ic ,iceland spar1 refractive index of1 #ajc ,ice1 refractive index of1 #ajc ,i4,d4,b4 laws 7,illicit ,diamond ,buying71 #cf ,ilmenite1 #bj ,india1 diamonds in1 #d ,inverel diamonds1 #ia ,internal strain in diamonds1 #ajd ,iron a solvent for carbon1 #aaf -- ore1 density of1 #ic -- pyrites1 #bj ,jagersfontein diamond1 #gi -- ,mine1 #ad -- -- characteristics of diamonds from1 #fh ,jeffreysite1 #bj ,kafirs1 #db ,kamfersdam ,mine1 #ae -- -- characteristics of diamonds from1 #ff ,kenilworth depositing floors1 #dg ,kimberley1 #f -- blue ground1 #aj -- mines1 #ad1 #bc1 #cd -- ,mine in old days1 #be -- -- at the present day1 #cd -- -- characteristics of diamonds from1 #fc -- shales1 #ae -- ,west ,mine1 #ae -- -- -- characteristics of diamonds from1 #ff ,kirsten's automatic diamond collector1 #eg ,klipdam1 #h1 #bc ,koffyfontein ,mine1 #ad ,koh-i-noor diamond1 #hj -- hardness of1 #ia ,kyanite1 #bj1 #ga ,lamp1 ultra-violet1 #ig ,leicester ,mine1 #ae1 #bc -- -- characteristics of diamonds from1 #fg ,loterie d',angleterre diamond1 #hj ,lustre of rough diamonds1 #ef ,machinery for washing and concentrating1 #di ,macles1 #hf ,magnetite1 #bj1 #ga -- density of1 #ic ,maskelyne on diamonds1 #a ,matabele1 #ab1 #ci ,matrix of diamond1 #fg ,melaphyre1 #aj1 #af ,melting-point of carbon1 #aaj ,meteor1 ,canyon ,diablo1 #acf ,meteoric diamonds1 #acd ,meydenbauer on meteoric diamonds1 #ace ,mica1 #bj1 #ga -- density of1 #ic ,moissan's experiments on the genesis of diamond1 #aae ,mud volcano1 #bd ,nassak diamond1 #hj ,natal1 coal in1 #f ,natural formation of diamond1 #abg ,newlands ,mine1 #ae -- -- characteristics of diamonds from1 #fg ,new ,rush diggings1 #bf ,nizam of ,hyderabad diamond1 #hj ,noble1 ,sir ,a41 experiments1 #abb1 #aca ,noteworthy diamonds1 #gf ,octahedral crystals of diamond1 #fc1 #hf ,olivine1 #bj -- diabase1 #af ,orange ,river ,colony1 coal in1 #f -- -- -- diamonds in1 #ad ,orloff diamond1 #hj ,pasha of ,egypt diamond1 #hj ,paterson1 ,mr41 description of ,kimberley in old days1 #be ,peridot1 #bj1 #aci ,peridotite1 #c ,perofskite1 #bj ,phosphorescence of diamonds1 #if ,phosphorus1 refractive index of1 #ajc ,physical properties of diamond1 #hi ,picking tables1 #ea ,pipes or craters1 #ah ,pitt diamond1 #hj ,polarised light and diamond1 #ajd ,pole ,star diamond1 #hj ,pondos1 #ci1 #db ,premier ,mine1 #ae1 #gf ,prodigious diamonds1 #gf ,pseudobrookite1 #bj ,pulsator1 #eb ,pyrope1 #gj ,quartzite1 #af1 #bj -- density of1 #ic -- refractive index of1 #ajc ,radio-activity of diamond1 #aji ,radium1 action on diamond1 #ajh 8,reef10 #ba ,refractive indices1 #ajc ,refractivity of diamond1 #ajb ,regent diamond1 #hj ,reunert1 ,mr41 description of ,kimberley ,mine1 #cj ,rhodes1 ,cecil ,john1 #cd ,river washings1 #g ,rock shafts1 #dc ,rntgen rays1 diamond in1 #ajg ,ruby1 refractive index of1 #ajc ,rutile1 #bj ,sahlite1 #bj ,sancy diamond1 #hj ,savings of the native workmen1 #da ,scalenohedron diamond crystal1 #hf ,serpentine1 #ai ,shafts1 rock1 #dc ,shah diamond1 #hj ,shales1 ,kimberley1 #ae ,shangains1 #ci ,shells in blue ground1 #ba ,shot boart1 #ha ,silver and thallium1 nitrate of1 #id ,smaragdite1 #bj ,soft blue ground1 #dg ,sorting the diamantiferous gravel1 #ee ,specific gravity1 see ,density ,spectrum1 absorption of diamond1 #aja ,sphalerite1 #ajj ,spinthariscope1 #ajh ,sprat's ,history of the ,royal ,society1 #a ,sprouting graphite1 #hd ,star of the ,south diamond1 #hj ,stones other than diamonds1 #gj1 #ga1 #ic1 #ie ,strain1 internal1 in diamonds1 #ajd ,sulphur1 refractive index of1 #ajc ,swazis1 #ci ,ultra-violet lamp to show phosphorescence1 #ig ,underground workings1 #dc ,united ,states1 diamonds in1 #b ,vaalite1 #bj ,vaal ,river1 #h1 #af ,valuators1 #gc ,value of diamonds per carat1 #ab1 #fi ,value of diamonds1 progressive increase in1 #fi ,vermiculite1 #bj ,volatilisation of carbon1 #aae ,volcanic necks1 #ah ,volcano1 mud1 #bd ,wages1 scale of1 #ce ,washing and concentrating machinery1 #di ,wesselton ,mine1 #ad1 #ae1 #bc1 #ce -- -- characteristics of diamonds from1 #fe ,willemite1 #ig ,wollastonite1 #bj ,workings1 underground1 #dc ,yellow ground1 diamantiferous1 #ai ,yield of diamonds1 annual1 #fj -- -- -- total1 #ce -- falls off with depth1 #fh -- per load of blue ground1 #fb ,zimbabwe ruins1 #dj ,zircon1 #bj1 #ei1 #ga -- density of1 #ic ,zulus1 #ab1 #ci1 #dj ,w4 ,,brendon ,,and ,,son1 ,,ltd41 ,,printers1 ,,plymouth ,,footnotes3 #a ,chemical ,news1 ,vol4 ,i1 p4 #bjh4 #b ,mr4 ,paterson called 8limey stuff0 what is now termed 8blue ground40 ,it was also formerly called 8marl stuff10 8blue stuff10 and 8blue clay40 #c ,the original name for the ,kimberley ,mine4 ,it was also sometimes known as 8,colesberg ,kopje40 #d ,diamonds and ,gold in ,south ,africa4 ,by ,t4 ,reunert4 ,johannesburg1 #ahic4 #e ,according to ,gardner ,williams the ,south ,african carat is equivalent to #cagd grains4 ,in ,latimer ,clark's ,dictionary of ,metric and other ,useful ,measures the diamond carat is given as equal to #cafhc grains #jbjec gramme #d diamond grains2 #a diamond grain #jgib troy grain2 #aeae diamond carats #a ounce troy4 ,webster's ,international ,dictionary gives the diamond carat as equal to #c troy grains4 ,the ,oxford ,english ,dictionary says the carat was originally #a_/add of an ounce1 or #c grains1 but now equal to about #c grains1 though varying slightly with time and place4 ,the ,century ,dictionary says the diamond carat is equal to about #c troy grains1 and adds that in #ahgg the weight of the carat was fixed by a syndicate of ,london1 ,paris1 and ,amsterdam jewellers at #bje milligrammes4 ,this would make the carat equal to #cafc troy grains4 ,a law has been passed in ,france ordaining that in the purchase or sale of diamonds and other precious stones the term 8metric carat0 shall be employed to designate a weight of #bjj milligrammes 7#cjhf grains troy71 and prohibiting the use of the word carat to designate any other weight4 #f ,artificial tribo-luminescent sphalerite3-- ,zinc carbonate #ajj parts ,flower of sulphur #cj 0 ,manganese sulphate per cent4 ,mix with distilled water and dry at a gentle heat4 ,put in luted crucible and keep at a bright red heat for from two to three hours4 #g ,sir ,james ,dewar1 in a ,friday evening discourse at the ,royal ,institution in #ahhj1 showed an experiment proving that the temperature of the interior of a carbon tube heated by an outside electric arc was higher than that of the oxy-hydrogen flame4 ,he placed a few small crystals of diamond in the carbon tube1 and1 maintaining a current of hydrogen to prevent oxidation1 raised the temperature of the tube in an electric furnace to that of the arc4 ,in a few minutes the diamond was transformed into graphite4 ,at first sight this would seem to show that diamond cannot be formed at temperatures above that of the arc4 ,it is probable1 however1 for reasons given above1 that at exceedingly high pressures the result would be different4 #h ,the silica was in the form of spheres1 perfectly shaped and transparent1 mostly colourless1 but among them several of a ruby colour4 ,when #e per cent of silica was added to cordite1 the residue of the closed vessel explosion contained a much larger quantity of these spheres4 #i ,a pressure of fifteen tons on the square inch would exist not many miles beneath the surface of the earth4 #aj ,there are abundant signs that a considerable portion of this part of ,africa was once under water1 and a fresh-water shell has been found in apparently undisturbed blue ground at ,kimberley4 #aa ,the water sunk in wells close to the ,kimberley mine is sometimes impregnated with paraffin1 and ,sir ,h4 ,roscoe extracted a solid hydrocarbon from the 8blue ground40 #ab ,chemical ,news1 vol4 lxi1 p4 #bji1 #ahij4 ,,transcriber',s ,,note ,obvious typographical errors and punctuation errors have been corrected after careful comparison with other occurrences within the text and consultation of external sources4 ,all misspellings in the text1 and inconsistent or archaic usage1 have been retained3 for example1 unfrequent2 clayey2 friable2 slaty2 imbed2 stoped2 peculation2 situate4 ,in the ,table of ,contents1 the ,index page number #8#ade' has been replaced by #8#ada'4 ,in the ,index1 #8,colesberg ,copje' has been replaced by #8,colesberg ,kopje'1 and #8,de,beers' has been replaced by #8,de ,beers'4