January 4, 19 12] 



NATURE 



organic matter. The first runnings are put into a pan and 

 further concentrated by exposure to the sun, or by boil'ng 

 over a fire until a mixture of sodium chloride and potassium 

 nitrate, with varying quantities of sodium sulphate and 

 magnesium nitrates, separates out. This is sold to the 

 refiner as crude saltpetre. The mother liquor is thrown on 

 to the heap of saltpetre earth, the so-called factory, to 

 which are also added the wet soil from the " Kuria " and 

 the weaker solution of nitrates coming out in the later 

 stages of the percolation, and requiring too much fuel to 

 make further concentration worth while. After a time the 

 heap can again be extracted, and so the process goes on 

 perpetually. Fresh village earth is constantly being added, 

 but no special additions of organic matter seem to be 

 made. 



At the refinery the crude saltpetre, the impurities of 

 which are soil, sodium sulphate, sodium chloride, and 

 magnesiuoi nitrate, is added to a boiling mother liquor 

 from a previous operation. This liquor, being already 

 saturated with sodium chloride and sodium sulphate, only 

 dissolves the nitrate. When the insoluble matter has sub- 

 sided, the clear liquor is run into wooden vats, and on 

 cooling deposits a good deal of potassium nitrate, that 

 only requires to be drained and slightly washed to be 

 ready for market. The insoluble material still contains 

 some potassium nitrate, and is thrown out on to the 

 factory heap of nitre earth, from which more nitrate is 

 subsequently again extracted as before. The mother liquor 

 cannot be used indefinitely for the purification of the crude 

 saltpetre, but it is not wasted. When it becomes too 

 impure for further use, it is concentrated to deposit some of 

 the sodium chloride, and the final liquor is simply thrown 

 on to the factory heap again. Whilst the extraction process 

 is remarkably efficient, considering that it has been evolved 

 by the natives themselves without outside help, the refinerv 

 process is admittedly wasteful, and various improvements 

 are suggested by Messrs. Leather and Mukerji. 



GEOPHYSICAL RESEARCH.' 



T^O write the history of the earth is a very different 

 undertaking from writing the history of a people. In 

 the latter case, a diligent seeker can usually find some 

 ancient monastery where far-sighted historians of an earlier 

 generation have collected Ihe more important records which 

 he requires, and placed them within reach of his hand. 

 With the earth's history, which is the province of geology, 

 it is another matter. The great globe has been millions 

 of years in the making, and, except for a mere fragment 

 of its most recent history, it has had neither a historian 

 nor an observer. Its formation has not only extended over 

 an almost incomprehensible interval of time, but we have 

 no parallel in our limited experience to help us to under- 

 stand its complicated development, and no svstem of classifi- 

 cation adequate to the task, even of grouping in an orderly 

 way all the observed rock and mineral formations with 

 reference to the forces which moulded them. And even if 

 we could correctly interpret all the visible rock records, we 

 are still quite helpless to comprehend all those earlier 

 activities of the formation period, the record of which is 

 now obliterated. 



To the student of the earth's history, therefore, the 

 problem of gathering and ordering such a widely scattered 

 and heterogeneous collection of effects and causes is one of 

 somewhat overwhelming scope and complication. In the 

 industrial world, a situation of this kind soon results in 

 replacing individual effort with collective effort, in the 

 organisation of a system of a scope more appropriate to 

 the magnitude of the task. We are familiar with indus- 

 trial organisation and the wonderful progress in the 

 development of American industries which has everywhere 

 followed it. We are also familiar with organised geo- 

 logical surveys and the success which has attended them 

 in geological and topographical classification. But the idea 

 of organising research to meet a scientific situation of 

 extraordinary scope and complexity is still comparatively 

 1 Presidential address delivered at the 700th meetingr of the Philosophical 

 Society of Washington, November 25, 191 1. by Dr. Arthur L Day 

 Reprinted from the Journal of the Waihington Academy of Sciences, 

 Derember 4, 1311. 



NO. 2201, VOL 



88] 



new. The very words science and research are still re- 

 garded as referring to something out of the ordinary, 

 something to be withheld from the common gaze, to be 

 kept hidden in a special niche, behind a mysterious curtain 

 and served by priests of peculiar temperament and un- 

 practical ideals. This is both disparaging to our good 

 sense and prejudicial to the progress of knowledge. Scien- 

 tific research is not a luxury ; it is a fundamental necessity. 

 i It is not a European fad, but is the very essence of the 

 I tremendous technologic and industrial success of the last 

 i twenty years, in which we have shared. 



Prof. Nichols, of Cornell, as retiring president of the 

 American Association for the Advancement of Science, put 

 the case in this way : " The main product of science (re- 

 search) ... is knowledge. Among its by-products are the 

 technologic arts, including invention, engineering in all its 

 branches, and modern industry." The idea of scientific 

 research is therefore not less tangible than industrial 

 development, or less practical ; it is merely one step more 

 fundamental ; it is concerned with the discovery of prin- 

 ciples and underlying relations rather than their applica- 

 tion. This being true, research should profit as much 

 from efficient organisation as industrial development has 

 done, or even more. 



Although this conclusion is making its way but slowly 

 in American science, in geological research, where material 

 must be gathered from the utmost ends of the earth and 

 even from within it, and where nearly every known branch 

 of scientific activity finds some application, there is a 

 peculiarly favourable opportunity for organised effort which 

 is already coming to be recognised. " So long as geology 

 remained a descriptive science," says President Van Hise, 

 of Wisconsin, " it had little need of chemistry and physics; 

 but the time has now come when geologists are not satis- 

 fied with mere description. They desire to interpret the 

 phenomena they see in reference to their causes — in other 

 words, under the principles of physics and chemistry. . . . 

 This involves cooperation between physicists, chemists, and 

 geologists." 



In a general way, physics, chemistry, and biology have 

 already supplied working hypotheses which have been used 

 by students of geology to help in the examination, classifi- 

 cation, and mapping of the most conspicuous features of 

 the exposed portion of the earth. The geologist has gone 

 abroad and has studied the distribution of land and water, 

 the mountain ranges, the erosive action of ice and of 

 surface water and the resulting sedimentary deposits, the 

 distribution of volcanic activity and of its products, the 

 igneous rocks ; or more in detail he has studied the appear- 

 ance of fossils in certain strata, and has inferred the 

 sequence of geologic time. The distribution of particular 

 minerals and of ore deposits has been carefully mapped. 

 Regions which offer evidence of extraordinary upheaval 

 through the e.xercise of physical forces have been pains- 

 takingly examined, and so on through the great range of 

 geologic activity. In a word, the field has been given a 

 thorough general examination ; but the manifold problems 

 which this examination has developed, although early 

 recognised, and often the subject of philosophical specula- 

 tion and discussion, still await an opportunity for quanti- 

 tative study. They are often problems for the laboratory 

 and not for the field, problems for exact measurement 

 rather than for inference, problems for the physicist and 

 chemist rather than for the geologist. This is not a result 

 of oversight ; it is a stage in the development of the science 

 — first the location and classification of the material, then 

 the laboratory study of why and how much. 



Certain indications have led us to believe, for example, 

 that the earth was once completely gaseous and in appear- 

 ance much like our sun. Indeed, it possibly formed a part 

 of the sun, but through some instability in the system 

 became split off — a great gaseous ball which has cooled to 

 its present condition. The cooling probably went on 

 rapidly at first until a protecting crust formed about the 

 ball, "then more and more slowly, until now. when our 

 loss of heat by radiation into space is more than com- 

 pensated by heat received from the sun. Obviously, the 

 earliest portions of this history are. and must remain, 

 dependent upon inference, but the formation of a solid 

 crust cannot advance far before portions of it become fixed 

 in a form such that further disturbance do^s not destroy 



