Ib2 



NA TURE 



Yjfune 20, 1889 



scientific bases of commercial geography should be laid ; and his 

 paper, combined with what is being done elsewhere, leads us to 

 hope that that hitherto ill-used and profitless subject may yet 

 ■be worthy of a high place in technical education. In the same 

 magazine is the report of an address by M. Kropotkin on the 

 study »f geography, which we commend to all interested in this 

 important subject. 



At the recent German Geographentag, Dr. Eschenhagen, of 

 the Imperial Marine Observatory, described the results of his 

 magnetic survey of the Harz Mountains, begun last autumn, and 

 comprising about 3000 measurements. He has shown that no 

 connection can be proved to exist between the ancient geological 

 line of fracture of the Harz and the distribution of terrestrial 

 magnetism, such as Naumann demonstrated in the case of Japan. 

 Dr. Eschenhagen has extended his explorations in terrestrial 

 magnetism over the whole of the north-west of Germany, so 

 that, inasmuch as a similar survey of Austria-Hungary will be 

 completed about 1892, our knowledge of the distribution of 

 terrestrial magnetism in Central Europe has made a great 

 advance. 



Dr. O. Krummel contributes to the current number oi Peter- 

 matin's Mitteihmgen an important paper on erosion through the 

 agency of tidal currents, in which, by a careful examination of 

 several specific instances, he endeavours to come to some con- 

 clusion as to the laws which govern the erosive work performed 

 by the tides. There is paper of some practical importance on 

 the suitability of Central Asia for Russian colonization, by 

 General Annenkof. 



The number of the Boletino of the Lisbon Geographical 

 Society is entirely occupied by a long paper in French, by M. 

 A. Marques, giving a detailed account of the Samoan Islands 

 in all their aspects. As a summary of our knowledge of these 

 islands, the paper will be found useful. 



In the current number (4) of the Mittheilungen of the Vienna 

 Geographical Society will be found the first p irt of a paper, by 

 Herr Janko, on the development and topography of the Rosetta 

 mouth of the Nile. 



Dr. Schweinfurth writes with great satisfaction of his 

 journey in Hodeida, in Southern Arabia, in the early part of the 

 present year. Among the places he visited were Khalife, at 

 the foot of the Jebel "Bura, Wolleje, the Jebel Melhan, Bajil, 

 Hojela, Wossil, and Jebel Harrassa. The climate he found quite 

 European, the nights bitterly cold, though it was hot enough for 

 an hour or two in the middle of the day. Dr. Schweinfurth's 

 botanical collections exceeded all his expectations ; the moun- 

 tain-slopes are covered with vegetation. He sent home some 

 600 species (1803 specimens), besides seeds and living plants. 



In a very able memoir published by the Danish Society of 

 Northern Antiquaries (in English), Prof. Gustav Storm redis- 

 cusses the vexed question of the Vinland voyages of the Norse 

 colonists of Greenland, for the purpose of determining as 

 accurately as the data will permit the various lands mentioned in 

 the old Sagas. " Helluland," Prof. Storm is inclined to think, 

 must be Labrador ; Markland corresponds to Newfoundland, 

 and Vinlan 1 to Cape Breton Island and Nova Scotia. 



Mr. J. Y. Buchanan has been appointed Lecturer in Geo- 

 graphy at the University of Cambridge. 



It is reported from Sydney that the New South Wales branch 

 of the Royal Geographical Society is sending an explorer, 

 Mr. Arthur J. Vogan, to gather information relative to the far 

 interior. Mr. Vogan will travel northwards from Fort Bourke 

 to Pitchiri Creek, on the Upper Mulligan (lat. 21° S.), and after 

 exploring the country from that point to the Herbert River, will 

 either make his way to the Gulf of Carpentaria or to Hughenden. 

 Mr. Vogan intended leaving Sydney during May. 



AL UMINIUM.^ 



r^HEMISTS of many lands have contributed to our knowledge 

 ^-^ of the metal aluminium. Davy, in 1807, tried in vain to 

 reduce alumina by means of the electric current. Oerstedt, the 

 Dane, in 1824. pointed out that the metal could be obtained by 

 treating the chloride with an alkali metal ; this was accom- 

 plished in Germany by Wohler in 1827, and more completely 

 in 1845, whilst in 1854, Bunsen showed how the metal can be 



* The Friday evening discourse delivered by Sir Henry Roscoe, M.P., 

 D.C.L., LL.D., V.P.R.S., at the Royal Institution of Great Britain, on 

 May 3, 1889. 



obtained by electrolysis. But it is to France, by the hands of 

 Henri St. Claire Deville, in the same year, that the honour 

 belongs of having first prepared aluminium in a state of purity, 

 and of obtaining it on a scale which enabled its valuable 

 properties to be recognized and made available, and the bar of 

 "silver-white metal from clay," was one of the chemical 

 wonders in the first Paris Exhibition of 1855. Now England 

 and America step in, and 1 have this evening to relate the im- 

 portant changes which further investigation has effected in the 

 metallurgy of aluminium. The process suggested by Oerstedt, 

 carried out by Wohler, and modified by Deville, remains in 

 principle unchanged. The metal is prepared, as before, by a 

 reduction of the double chloride of aluminium and sodium, by 

 means of metallic sodium in presence of cryolite ; and it is 

 therefore not so much a description of a new reaction as of 

 improvements of old ones of which I have to speak. 



I may perhaps be allowed to remind my hearers that more 

 than thirty-three years ago, Mr. Barlow, then secretary to the 

 In titution, delivered a discourse, in the presence of M. Deville, 

 on the properties and mode of preparation of aluminium, then a 

 novelty. He stated that the metal was then sold at the rate of 

 ;i^3 per ounce, and the exhibition of a small ingot, cast in the 

 laboratory by M. Deville, was considered remarkable. As 

 indicating the progress since made, I may remark that the 

 metal is now sold at 20s. per pound, and manufactured by the ton, 

 by the Aluminium Company, at their works at Oldbury, near 

 Birmingham. The improvements which have been made in this 

 manufacture by the zeal and energy of Mr. Castner, an American 

 metallurgist, are of so important a character, that the process 

 may properly be termed the Deville-Castner process. 



The production of aluminium previous to 1887, probably did 

 not exceed 10,000 pounds per annum, whilst the price at that time 

 was very high. To attain even this production required that at 

 least 103,000 pounds of double chloride, and 40,000 of sodium 

 should be manufactured annually. From these figures an idea 

 of the magnitude of the undertaking assumed by the Aluminium 

 Company may be es'imated, when we learn that they erected 

 works having an annually producing capacity of 100,000 pounds 

 of aluminium. To accomplish this, required not only that at least 

 400,000 pounds of sodium, 800,000 of chlorine, and 1,000,000 

 of double chloride, should be annually manufactured, but 

 in addition that each of these materials should be produced at a 

 very low cost, in order to enable the metal to be sold at 20.i-. 

 per pound. 



The works, which now cover a space of nearly five acres, are 

 divided into five separate departments, viz. (i) sodium ; (2) 

 chlorine ; (3) chloride'; (4) aluminium ; and (5) fouridry, rolling, 

 wire mills, &c. 



In each department an accurate account is kept of the pro- 

 duction each day, the amount of material used, the different 

 furnaces and apparatus in operation, &c. In this manner it has 

 been found possible to ascertain each day exactly how the 

 difierent processes are progressing, and what effect any modifi- 

 cation has, either on cost, quantity, or quality of product. By 

 this means a complicated chemical process is reduced to a series 

 of very simple operations, so that whilst the processes are 

 apparently complicated and difficult to carry out successfully, this 

 is not the case now that the details connected with the manu- 

 facture have been perfected, and each operation carried on 

 quite independently until the final materials are brought together 

 for the production of the aluminium. 



Manufacture of Sodium. 



The first improvement occurs in the manufacture of sodium by 

 what is known as the " Castner process." The successful work- 

 ing of this process marks an era in the production of sodium, as 

 it not only has greatly cheapened the metal, but has enabled the 

 manufacture to be carried out upon a very large scale with little 

 or no danger. Practically, the process consists in heating fused 

 caustic soda in contact with carbon whilst the former substance 

 is in a perfectly liquid condition. By the process in vogue before 

 the introduction of this method, it was always deemed necessar}- 

 that special means should be taken to guard against actual fusion 

 of the mixed charges, which, if it were to take place, would to a 

 large extent allow the alkali and reducing material to separate. 

 Thus, having an infusible charge to heat, requiring the employ- 

 ment of a very high temperature for its decomposition, the iron 

 vessels must be of small circumference to allow the penetratioi 

 of the heat to the centre of the charge without actually meltind 

 the vessel in which the materials are heated. By the new prol 



