232 



KNOWLEDGE. 



June, Mil. 



.^tain upon a telegraph form, which was supposed to ha%'e been 

 produced by the saliva of a person who had taken cocaine 

 was examined in the same way, and here, too, an unmistakable 

 reaction was obtained. 



ACTION OF STEAM UPON CARBON AND LIMK,— 

 The possible mode of formation of marsh gas and other 

 natural gases rich in methane is suggested by the results of 

 experiments made by M. L, \Mgnon (Comptcs Rcndiis. 1911, 

 CLII, 871) upon the action of steam upon a mixture of carbon 

 and lime. It was found that the steam was decomposed more 

 rapidly and at a lower temperature bj- a mixture of car- 

 bonaceous substances and lime than by the carbon alone. 

 Thus when the steam was conducted through the mixture 

 contained in a porcelain tube heated to about 600' to 800' C, 

 the resulting gas was found to contain hydrogen, methane, 

 carbon monoxide, oxygen, and nitrogen, the proportions 

 depending upon various factors such as the quantity of 

 steam present, and the duration of contact between the 

 excess of steam and the methane formed, more or less 

 decomposition taking place in accordance with the equaticm — 



CH4 + HoO = CO + 3H, 

 Thus tw-enty-eight per cent, of methane was produced by the 

 passage of five grammes of steam during thirty-five minutes, 

 whereas only about eight per cent, was obtained after the 

 passage of fifteen grammes of steam during two hours. By 

 regenerating the lime from the calcium carbonate produced it 

 was found possible to transform the whole of the organic 

 substances present into hydrocarbons in the following manner 



2C + CaO + 2H,0 = CaCO^ + CH4 

 and CaCO, = CaO + CO. 



or combining the two equations — 



2C + 2HoO = CO, + CH4 

 Since the methane requires a lower temperature for its 

 formation than that of the decomposition of the calcium 

 carbonate, the two gases may be collected separately. 



It is suggested that these experiments also throw light upon 

 the formation of petroleum deposits. When animal and 

 vegetable remains are left in contact with water in the 

 presence of calcareous deposits, hydrocarbons are produced, 

 and it is quite possible that these, under the influence of 

 various physical conditions of pressure, and so on, have been 

 transformed into petroleum compounds. 



GEOLOGY, 



By Russell F. Gwixxell, B.Sc, A.R.C.S., F.G.S. 



CARBON IN COLD ORE.— The well-known auriferous 

 conglomerates of the Witwatersrand, known as " banket," 

 consist of beds of coarse well-rolled quartz pebbles, 

 together with smaller pebbles, the whole being cemented 

 into a compact rock by means of secondary silica. 

 They are obviously shore deposits, and are of very great — 

 perhaps pre-Cambrian-age. The gold occurs in the matrix 

 and not in the pebbles themselves. Pyrites is conimonlv 

 present, and also in places, carbonaceous or graphitic matter. 

 As the origin of the gold appears to be intimately related to 

 that of the other "impurities," it is a matter of considerable 

 interest to determine the source of the carbon. This latter has 

 been regarded as organic matter which directly precipitated 

 the gold from solution, although this seems hardly likely in 

 face of the fact th.at there is neither gold nor carbon in the 

 finer sediments which are associated with the b.anket. For a 

 fine sediment is naturally expected to yield organic matter in 

 greater abundance than does a coarse conglomerate. Writing 

 in the Transactions of the Geological Society of Soiitli 

 Africa (Vol, ,\III., 1910), on "The Mode of Occurrence and 

 Genesis of the Carbon in the Rand Bankets," Mr, C, Baring 

 Horwood shows that from its mode of occurrence the carbon 

 is of later date than the bankets, and is of inorganic origin. 

 Gold can be found not only as a film on the particles of carbon, 

 but also actually embedded in the latter. The carbon occurs 

 frequently in small irregular spheroids sometimes actually 



replacing the quartz, and it is almost invariably closely 

 associated with pyrites when the latter is present. Further- 

 more, it occurs chiefly along and on both faces of partings in 

 the banket and along planes obli(jue to the bedding. These 

 facts cannot well be accounted for by any theory of organic 

 origin. Indeed the mode of occurrence of the carbon strongly 

 recalls the crystals of tourmaline of pneumatolytic origin, found 

 on the surface of joint planes in the red granite of the Bushveld. 

 The author's researches lead to the conclusion that the carbon 

 is of deep-seated origin and owes its presence in the bankets 

 to associated igneous magma, probably through the agency of 

 pneumatolysis. Other authors have ascribed an inorganic 

 origin to certain petroleums, and have included both graphite 

 and diamond as the end products of the petroleum series. 

 Now, great diabase dykes penetrate the Rand country, and to 

 these one would naturally look for the source of the carbon 

 (and incidentally of the gold). Analyses shew that carbon is 

 distributed evenly throughout the igneous rock, which would 

 hardly be the case if it were derived from organic fragments 

 caught up and enclosed in the molten magma at the time of 

 its intrusion. The fact that gold is not found, as is the carbon, 

 distributed about equally in dyke-rock and in banket is easily 

 accounted for by its relatively greater solubility. On this 

 account, subse(iuent leaching-out of the gold has removed it 

 from the dyke-rock. Summarily, the study of the carbon in 

 those mines of the Rand where it is most typically developed 

 certainly shows that its occurrence is closely associated with 

 that of the pyrites and gold, and indicates a close relationship 

 between its presence and that of neighbouring igneous rocks 

 which contain carbon. The occurrence of the carbon in tiny 

 spheroids scattered through the matrix of the bankets points 

 to deposition from gaseous or very mobile liquid hydrocarbons, 

 before the final cementation and induration of the bankets by 

 the deposition of secondary silica. Taken in conjunction with 

 the known facts of its occurrence in other parts of the world, 

 it is reasonable to attribute its origin to magmatic vapours 

 or solutions derived from the neighbouring basic igneous 

 intrusions before their final consolidation. 



LABRAHOK, A LAND OF PROMISE.— In the 

 Oeograpliical Journal for April, Dr. Wilfred T. Grenfell 

 sings the praises of Labrador after an acquaintance with it 

 of twenty years. The country has been greatly neglected up 

 to the present time and little knowledge exists of its resources 

 beyond its coastal portion. Vet the author is confident that 

 Labrador can and will carry, in the days to come, a population 

 as easily as Norway does to-day. It is a better country by 

 far than Iceland, and until the wizard hand of man was 

 turned to New Mexico, Arizona or even to parts of Egypt 

 and West Australia it was able to offer as good attractions to 

 settlement as any of them, " If ever a race shall rise to 

 people her glorious fjords and inlets, and to wrest her 

 undoubted wealth from her forests and mines, she will, like all 

 northern countries, evolve a people endowed with those 

 sterling physical qualities that characterised the Vikings of 

 old." The agricultural outlook of Labrador is not hopeful 

 owing to the fact that the super-incumbent rocks have been 

 removed by glaciation from the .Archaean floor, which is thus 

 laid bare over much of the country. On the other hand this 

 fact need not injure the prospects of the development of 

 mineral resources. While very little serious geological work 

 has been done, the deductions of the few prospectors who 

 have visited the country show every possibility of valuable 

 mineral deposits. The inland resources are almost unknown, 

 but near the coast several deposits of economic value have 

 been found, and in some cases worked ; among these are 

 alluvial gold, antimony, mica, copper, iron pyrites and garnet. 

 Coal which may be a continuation of the seams of Cape Breton, 

 has been partially prospected. Finally, the beautiful 

 plagioclase felspar Labradorite, which derives its name from 

 the country and which exhibits an iridescent play of colours, 

 has been worked in an island near Nain, which consists 

 almost entirely of this mineral. 



AN IGNEOUS COMPLE.X AND ITS ORIGIN.- A 

 number of instances are now known of igneous rock-masses 



