4o6 



NA TURE 



[August 24, 1905 



Corstorphine in his interesting and exhaustive Presidential 

 Address last year. 



If we must regret that we never had the opportunity 

 of seeing the great pioneers and the earlier workers, we 

 may rejoice that we have been able to meet those who are 

 now actively engaged in continuing their labours ; the 

 period of cursory visits and fragmentary essays is closing 

 and the era of deliberate and systematic surveys is 

 beginning ; we now look for authoritative information to 

 the Cape Survey inaugurated by Dr. Corstorphine in 1895 

 and so ably continued by his successor Mr. Rogers ; to 

 the Transvaal Survey begun by Dr. Molengraaff in 1897 

 and auspiciously revived under Mr. Kynaston ; and to the 

 Natal Survey which .Mr. Anderson has so successfully 

 directed since 1901. I hope that it will not be long before 

 there is no part of South Africa outside the direct super- 

 vision of a systematic and well-ordered survey. 



There is perhaps some danger lest in a developing 

 country, where the commercial possibilities are prominently 

 before all eyes, the immense importance of such surveys 

 should be overlooked, and lest it should be thought that 

 what appears to be purely scientific research may be left 

 to take care of itself until the mineral wealth of the 

 country has been explored. I cannot enter too emphatic 

 a protest against such a view ; how closely the two interests 

 are knit together must be apparent to anyone who reflects 

 that the nature and sequence of the more northerly form- 

 ations which have yielded coal, diamonds, gold, and 

 metalliferous deposits can only be studied in the light of 

 the more intelligible geology of Cape Colony and Natal. 

 It is, moreover, immensely to the advantage of South 

 Africa that you have intimately connected with the mining 

 industry geologists of such training as Doctors Corstor- 

 phine, Molengraaff, and Hatch, who have all gained 

 valuable e.xperience upon geological surveys. 



I may now, perhaps, cease to speak merely as a re- 

 presentative of the visitors and identify myself more closely 

 with the Section as a whole ; for the most gratifying 

 feature of this meeting is that it is not merely a visit of 

 strangers who are enjoying your hospitality, but that ,vith 

 Section C of the British -Association is fused Section B 

 of the South African Association, so that for the tiine 

 being we are all colleagues ; and even such vexed questions 

 as the correlation of the rocks of the Transvaal or of 

 Rhodesia with those of the Cape, or the origin of Ban'set, 

 or of Blue Ground, or the extension of the Main Reef 

 Series (perhaps it is no longer necessary to include the 

 problem of the Dwyka conglomerate) can be discussed \y 

 us on the spot as members of the same body inspired by 

 the same earnest desire for truth. 



I began these preliminary remarks by asking that I 

 might be regarded as the spokesman of the visitors, and 

 therefore represented myself as a geologist visiting the 

 country for the first time. I must, however, make a frank 

 confession. Not only is this my second visit to the country, 

 but I have not even any claim to be called a geologist. 

 My training and experience have been such that upon 

 many of the questions which must be most interesting 

 to this Section I am not competent to form an opinion or 

 to appreciate properly the evidence. I must, therefore, 

 crave your indulgence if in this Address I refrain from 

 discussing any of the problems of surpassing interest which 

 naturally engage the attention of those who are occupied 

 with the study of South .African geology. It would inde./d 

 be an impertinence for "me to do so. 



I venture, however, to hope that the frontier between 

 geology and mineralogy is so ill-defined — if indeed a scien- 

 tific frontier can be said to exist — that the thoughts and 

 occupations of one who has confined himself to the study 

 of minerals, and that rather in the laboratory than in 

 the field, are not alien to the interests of Section C. 



Experimental Geology. 

 A somewhat lamentable aspect of modern science is the 

 vast array of unorganised facts which are awaiting co- 

 ordination ; this is too often because they have teen 

 amassed without any definite idea of the purpose which 

 they may serve ; consequently it may happen that laborious 

 observations belonging to one science may fail to attract 

 the regard of a neighbouring science merely for want of 

 the mutual acquaintance which would make' them service- 

 able to each other ; and in these days of e.Kclusive special- 

 NO. 1869, VOL. 72] 



isation the introduction which might lead to a happy 

 union is, perhaps, not brought about for years. Noie 

 can be more fully alive to the importance of such an 

 alliance than those whose work lies on the borderland 

 between different sciences ; the mineralogist, for example, 

 is in contact on the one side with the experimental sciences 

 of chemistry and physics, and on the other with geology, 

 which has scarcely yet entered the experimental stage. 

 He cannot fail to be impressed by the need of the appeal 

 to experiment on the geological side of the border, and 

 it is perhaps his duty to supply the want so far as lies 

 in his power. 



Owing to this very need some of the most difficuh 

 problems in geology are those concerned with the origin 

 of minerals and of the rocks which they compose. One 

 need but recall the many theories which have been held 

 about the origin of mineral deposits, the filling of metal- 

 liferous veins, the local concentration of certain minerals, 

 the distribution of various rock types, the existence of 

 rocI< magmas of diverse compositions, and the differenti- 

 ation of their constituents. Could the importance and 

 difficulty of such problems be better illustrated than in 

 South .4fr!ca, and by its two most valuable minerals, gold 

 and diamond? 



Now all these are problems in which direct appeal may, 

 and indeed must, be made to laboratory experiments ; the 

 well-defined minerals of which the earth's crust consists 

 do not, after all, number much more than 800, and of 

 these many have already been manufactured in the labor- 

 atory. Speculation upon the origin of rocks and minerals 

 should surely be controlled by the results of experiments, 

 and equally should experiment which is to be of service 

 to geology be guided by a knowledge of the problems to 

 which it is to be applied. It will be my object in the 

 present .Address to illustrate these principles by examples 

 drawn from recent experimental work which can be applied 

 to geological problems, and to indicate the course which 

 such research is likely to pursue in the immediate future. 



It seems to be sometimes expected of a Presidential 

 Address that it should contain a summary of the progress 

 of a science during past years, and this is no doubt very 

 useful and instructive ; but if we are to go forward in our 

 scientific work we must not be satisfied with the patient 

 accumulation of details, or content to congratulate our- 

 selves upon the number of them which have been amassed. 

 I venture to think that it is more profitable to take our 

 stand upon the actual work of to-day, and from that 

 tower of observation to look forward to the future rather 

 than backwards to the past ; to exclaim with the poet — 

 " No, at noonday in the bustle of man's work-time 

 Greet the unseen with a cheer 1 

 Bid him forward.'' 



It would be interesting enough to trace the history 

 of the artificial reproduction of minerals, beginning w'ith 

 the famous experiment of James Hall ; to follow the lines 

 that led to the development of the French School during 

 the last half of the nineteenth century ; to dwell on the 

 researches of Senarmont, Ebelmen, Daubr^e, and Sainte- 

 Claire Deville ; to show how the increasing study of petro- 

 graphy and the invention of the electric furnace have led 

 to renewed activity in the attempts to reproduce igneous 

 rocks and the lock-forming minerals ; to discuss the more 

 modern experiments of Fouqu^ and L^vy, Lagorio, 

 Loevinson-Lessing, and Morozewicz ; or to describe the 

 manufacture of many an interesting mineral by de Schulten 

 and others who are actively prosecuting research of this 

 nature, including such sensational achievements as the 

 production of the ruby by Fr^my and of the diamond by 

 Moissan. 



Instead, however, of attempting a survey of all that 

 has been done, or even of all that is being done in the 

 artificial reproduction of minerals, let me adhere to the 

 principle that I have laid down, and discuss only a few 

 of those researches, now being carried on, which promise 

 to be most fruitful because their methods and aims are 

 inspired by the discoveries and views of modern chemistry 

 and modern physics. 



Van 't Hoff's Work on the Salt Deposits. 



Among such researches the most remarkable are those 



conducted by Prof, van 't Hoff and his pupils during the 



last eight years upon the Stassfurt salt deposits. These 



