400 



NATURE 



[February 23, 1893 



in Greece. He is now engaged in preparing a comprehensive 

 memoir on the subject which may be expected to throw new light 

 on some questions of historical geography. 



Mr. Mackinder, in his fifth lecture for the Royal Geo- 

 graphical Society's education scheme, spoke of the chief lines of 

 communication between Asia and Europe and the ways by 

 which successive bands or hordes of Asiatic invaders forced a 

 passage into the heart of Europe. The routes across Asia Minor 

 from the Gate of Cilicia to the northern waters, and the thorough- 

 fare through the Balkan peninsula now traversed by the inter- 

 national railway, were shown to have guided the movements 

 of peoples and the formation or dissolution of nations from the 

 dawn of European history on to the present day. 



The United States appears to have entered the field as an 

 aggrandising power, taking up territory beyond the limits of the 

 continent of North America, The annexation of Hawaii seems 

 likely to be effected without remonstrance, and a footing has 

 also been obtained in San Domingo, the eastern part of the 

 island of Haiti. 



M^. A. Vaughan Williams has been exploring the region 

 round the mouth of the Sabi River in south-east Africa. He 

 has ascended the stream for thirty miles to the limit of tidal 

 influence. 



The orthography of African place names is a perpetual source 

 of confusion. It appears that in place of Zimbabwe or Zim- 

 babye we ought, in order to render the sound of the word used 

 by the people surrounding the ruins, to write " Zimbabghi." The 

 familiar name Mashonaland is in itself a corruption of the native 

 name, but is always pronounced Mashunaland, a pronunciation 

 to which the spelling ought to conform. 



Railways seem likely at last to become established in 

 China. The line from Teintsin to Taku has now been ex- 

 tended to the River Lan, a total distance of 130 miles, and is 

 being rapidly pushed northward, a considerable section being 

 already opened for passenger traffic. 



CAPTAIN BOWER'S JOURNEY IN TIBET. 



A T an extra meeting of the Royal Geographical Society, on 

 "^^ Monday night, Captain H. Bower described his recent 

 journey with Dr. Thorold across Tibet from west to east. They 

 set out from Leh on June 14, 1891, and were fortunate enough 

 to get well into Tibet before meeting any natives. Travelling 

 due east they crossed a pass of 18,400 feet, on the other side of 

 which lay the Horpa Cho, the highest lake yet met with in Tibet, 

 and probably the highest in the world, its altitude being 17,930 

 feet. Along the route eastward many other lakes were 

 passed, all salt and without outlet, the want of fresh water being 

 sometimes severely felt ; a kettleful of hailstones was a welcome 

 catch on one occasion. The travellers used ponies and donkeys 

 for carrying their loads, as yaks do not eat grain, and grass was 

 often not met with for many days' journey. At length, after 

 travelling east and south-east for about 700 miles, they were 

 stopped within 200 miles of Lhasa by the Tibetans, who paid no 

 attention to Chinese passports, and after much parleying in- 

 sisted on a complete change of route. The party had to retrace 

 their steps for several days' march, turn northward, and then make 

 their way east at a safer distance from the capital. It was now 

 the month of October and the crossing of passes over 18,000 

 feet, with temperatures of 15° or more below zero, in strong 

 wind was extremely trying. About the end of November, for the 

 first time for four months, the tents were pitched at a less altitude 

 than 15,000 feet, and soon afterwards Chiamdo was reached. 

 Here great difficulty was experienced with the lamas, who in- 

 sisted that no European should enter the town ; but by the 

 intervention of the Chinese Amban, whose power was really but 

 slight, the party was allowed to proceed, passing round the out- 

 side of the town. From Chiamdo to Batang the way was easy, 

 and no difficulties were experienced thereafter. At Ta-Chen-Lu 

 they entered China and reached Shanghai on March 29, 1892. 

 Throughout Central Tibet the authorities disclaimed the 

 sovereignty of China, maintaining that only the grand lama had 

 jurisdiction in that region. Many of the lamas met with were 

 educated and intelligent men, but not inclined to give informa- 

 tion. Much difficulty was experienced in getting the names of 

 lakes and mountains, no two Tibetans giving the same answer, 



NO. 12 17, VOL. 47] 



The fanaticism and distrust of the people created constant diffi- 

 culties, but Captain Bower, under the pretext of being a Budd- 

 hist with a peculiar ritual, succeeded in making observations for 

 position openly as part of a religious service, previous attempts 

 to do so by stealth having failed. 



THE CHEMISTRY OF OSMIUM. 



A N important addition to our knowledge of the chemical 

 ■^^ nature of this interesting element is contributed by Prof. 

 Moraht and Dr. Wischin, of Munich, to the current number of 

 the Zeitschrift fur Anorganische Chemie. Two years have 

 scarcely elapsed since the position of osmium in the periodic 

 system was finally decided by the painstaking re-determination 

 of its atomic weight by Prof. Seubert. Previous determinations 

 of the atomic weight of osmium had been made with material 

 which Seubert subsequently showed to be impure, and in con- 

 sequence the erroneous value, 198 '6, had been ascribed to it. 

 Indeed previous to the year 1878 the order of precedence as 

 regards atomic weight of the four metals of the platinum group 

 — gold 196'2, iridium I96'7, platinum 1967, and osmium 198 '6 

 — was entirely at variance with the order demanded by their 

 chemical and physical properties, and a standing contradiction 

 of the periodic law of Newlands and Mendeleef. In that 

 year, however, Seubert attacked the case of iridium, and as the 

 result of a series of determinations, made with the laborious 

 care which has characterised all his work, the atomic weight of 

 this metal, when obtained in a pure state, was shown 

 to be 192 '5, a number very different to that previously assigned 

 to it, and which was afterwards remarkably confirmed, even to 

 the decimal place, by an independent investigation by Joly. 

 Three years later Seubert made his celebrated re-determination 

 of the atomic weight of platinum, which resulted in the number 

 I94'3 being finally derived for the true atomic weight of the 

 perfectly pure metal. This value was likewise subsequently 

 confirmed by Halberstadt. In the year 1887 the position of 

 gold was decided by simultaneous independent re-determinaiions 

 of its atomic weight by Thorpe and Laurie in this country and 

 Kriiss in Germany, the two values being practically identical, 

 1967. Lastly,' in 1891, Seubert completed his work by re- 

 determining the atomic weight of osmium with a specimen of 

 the metal of practically perfect purity, with the result that the 

 old number, I98"6, was found to be entirely erroneous, due to 

 considerable quantities of impurities being present in the 

 samples previously employed, and that the real value of this 

 constant was 190 3, thus removing osmium from its former 

 situation at the end of the series and placing it in its proper 

 position at the head of it. 



The order of precedence of the metals of the platinum group 

 is therefore as follows : — Osmium I90'3, iridium 192 "5, platinuiii 

 194*3, ^nd gold 1967. This order is in full accordance with 

 the relative chemical and physical properties of these metals, 

 and the last outstanding exception to the periodic generalisation 

 has dfsappeared. 



Although the properties of pure metallicosmium, and particular- 

 ly its atomic weight, are now known with certainty, the nature 

 of its compounds is yet very little understood. Moreover, it is 

 evident from the result of the investigation of Prof. Seubert 

 that previous workers have been dealing with an impure metal of 

 atomic weight, I98'6. It was therefore desirable that not only 

 should the chemistry of this element be extended to compounds 

 hitherto uninvestigated, but that the composition and properties 

 of the compounds already known should be subjected to a re- 

 examination. 



Prof. Moraht and Dr. Wischin have therefore taken up the 

 study of the compounds of osmium with oxygen, sulphur, and 

 the halogens, employing material of a very high degree of 

 purity, and the results of their investigation are both novel and 

 interesting. 



Work with osmium compounds is endowed with peculiar 

 personal danger to the chemist, owing to the great facility ex- 

 hibited under the most various conditions for the formation of 

 the tetroxide OSO4, a substance which boils at 100° C, and is 

 very volatile at the ordinary temperature, and which attacks the 

 skin, the lungs, and particularly the eyes with most serious con- 

 sequences. 



The material started with was a comparatively pure sample of 

 the best known salt containing osmium, potassium osmate, 

 K2OSO4.2H2O. This salt was further purified by distillation 



