2IO 



NA TURE 



[Dec. 30, 1880 



absDrbable wave-lengths become more rare the greater the atmo- 

 spheric layer the rays have already traver.ed. The author cal- 

 culates from hi.i experiments the proportion of carbonic acid in 

 the atmosphere, finding it 3'27 in 10,000 parts by volume ; a 

 number agreeing so well with results of chemical analysis as to 

 indicate that this is a good way of determining the carboni'; acid 

 in the atmosphere and its variations, applicable, too, at heights 

 where direct measurements are impossible. 



Herr Winkelmann proves by experiment [IVkJ. Ann. 

 No. II) that the heat-conduction of ethylene decreases e^omewhat 

 with increased pressure. The pressure was varied from 10 to 

 740 mm. (Comparative experiments with air showed no in- 

 fluence of pressure.) The author explains the phenomenon by 

 the divergence of ethylene from Boyle's law. The action of 

 cohec ion-forces between the molecules is indicated by that fact ; 

 and this will cause, at each collision, a temporary retardation of 

 the straight movements, which effect will occur oftener the 

 greater the number of collisions (i.e. the greater the den-ity). 

 Hence this retardation will increasingly affect the velocity «ith 

 which two contiguous layers of different temperature exchange 

 the energy of their motions. 



A REMARICABLE fall of rain in Austria and neighbouring 

 parts on August 11-15 '^'^ year, has been closely investigated 

 by Dr. Hann (JVien. Akad. Anz,), on the basis of data from 

 260 stations in Austria- Hungary, Bavaria, Switzerland, ai.d 

 Saxony. This fall caused the Danube at Vienna to reach (on 

 the iSth) its highest summer level in this century. The rain 

 began in Siebenburgen and south-east Hungary on the nth, 

 and in general went from east to west. It was most extensive 

 .on the I2th, and the heaviest fall was in Salzkammergut and 

 neighbourhood. The rain-area is found to lie on the west and 

 north-we-t side of the area of lowest air-pressure, and to ^^r^:tch 

 westw.irds far over the border of the minimum region. Near 

 the centre of lowes! pressure the precipitation was much less 

 than in several parts distant from it. The nonexistence of a 

 miniumm-producing power of rainfall (contrary to common 

 views), and the incapability of so great rainfall as that in the 

 present case attracting a minimum and influencing its propaga- 

 tion, are noteworthy. The general conclusion arrived at is that 

 no relation is demonstrable between barometric variation and 

 rainfall ; the fall of the barometer does not primarily depend on 

 the rainfall, and is not perceptibly influenced by it. Dr. Hann 

 finds this confirmed by an examination of several other heavy 

 rainfalls in their relation to distribution of air-pressure. 



The salt and the ice in cryohydrates have been regarded 

 by Prof. Guthrie as in chemical combination. In 1S77 

 Herr Pfaundler expresssed the view that cryohydrates were 

 merely mixtures of salt and ice. This view is also maintained 

 by Herr Offer, who in a recent paper to the Vienna Academy 

 raises various objections to the existence of cryohydrates as 

 chemical compounds. The numbers expressing the quaiitities 

 in which the water unites with the salts in various cryohydrates, 

 indicate no stoichiometric law, and tell much rather in favour of 

 chemical mixtures. No cryohydrate forms a clear anil pure 

 crystal, but always an opaque confused crystalline mass. The 

 phenomena which occur when cryohydrates are brought into 

 alcohol and into water are considered to be against Prof. 

 Guthrie's view. The heat-absorption of cryohydrates in dis- 

 solving, as compared w ith that of the salt and ice separately, 

 only presents differences which lie within the errors of observa- 

 tion. Further, Herr Offer compared the specific gravity of 

 several cryohydrates with those of their constituents, and found 

 pretty close agreement. 



From recent magnetic researches Herr Auerbach ( f^zVi/. An». 

 No. II) finds the temporary magnetism of cylindrical bodies, 

 ceteris paribus, proportional to the mass ; greater the greater the 

 length ; the less the thickness ; the greater the density ; depen- 

 dent only on form, not on size ; in the case of nickel, according 

 to density and force, a quarter to half as much as in iron. It 

 increases with magnetising force, first proportionally, then (cAcept 

 with very small density) more quickly, and at last more slowly. 

 The quick increase is greater the denser the body. The turn- 

 ing point is, for the same density, at the same place, but with 

 stronger forces the greater the density ; for magnetic saturation 

 of powders extremely strong forces are necessary. Herr 

 Auerbach theorises on these results. 



Another paper on magnetism in these Annalen is by Herr 

 Baur, and deals with the " function of magnetisation" for very 

 small magnetising forces ; the influence of temperature on it ; 



the magnetisability of iron at very high temperatures ; Gore's 

 phenomenon ; and the function for varieties of iron. Among 

 other re uhs, the smaller the magneti-ing force the greater is the 

 influence of temperature on the function in question. Up to a 

 certain force the function increases with increase in temperature, 

 but beyond that it decreases. With weak forces the temporary 

 magnetic moment rises quickly (with rise of te "perature) to a 

 maximum at red glow, then sinks quickly to nil; with strong 

 forces it gradually sinks, "ith rise of temperature, to a very 

 low value at red glow. With increased magnetic force Gore's 

 phenomenon becomes more intense and prolonged, and it occurs 

 at a higher glow. In ordinary iron the function of magnetisation 

 reaches its maximum very quickly, in iron filings later, and in 

 electrolytic iron very late. 



GEOGRAPHICAL NOTES 



The glacier of the Byeloukher Mountain, the chief summit of 

 the Siberian or Great Allay, which has not been visited by men 

 of science during the la't fifty years, was recently explored by an 

 expedition engaged in the study of the life of the West Siberian 

 natives. After having crossed the 90CO feet high Alps of the 

 Tchouya, the explorers descended into ihe pretty and wealthy 

 broad valley of the Tchouya, whence, following the Arkhyt River, 

 they soon reached the foot of the mighty Berel glacier. The 

 glacier, which forms in its lower parts a ?ner de glace two miles 

 long and 2S00 feet wide, was accurately explored and surveyed 

 during a week by the expedition from its lower end to a great 

 ice-fall, w-here the travellers were compelled to stop their work 

 before a moving wall of ice, while mighty masses of snow fell, one 

 after the other, on the glacier from the neighbouring mountains. 

 After having surveyed the glacier and made several drawings of 

 the severe scenery which it affords, the travellers returned to the 

 valley of Ouimon, and thence to the civilised towns. 



The astronomical determinations of positions which were made 

 by .M. Pyevtsoff' during his journey from Khobdo through Mon- 

 golia to Kalgan, and from Ourga to Kosh-agatch, are published 

 by Col. .Scharnhorst in the last number of the Iz-'estia of the 

 Russian Geographical .Society. They are most w elcome, as they 

 come from a country where exact determinations are very scanty. 

 — The same fascicule of the /"vj/w contain- M. Larionoff's cata- 

 logue of seventy-five determinations of heights in the northern 

 and eastern parts of the province of Kouldja and in the moun- 

 tains which border it north and ea^t ; and M. Severtsoff's map 

 of his route on the Pamir Rang-koul, south-east of the Lake 

 Kara-koul. 



The Russian travellers who have been engaged in the explora- 

 tion of Central Asia are now returning to St. Petersburg. Col. 

 Prshevalsky is expected every day, and the Russian Geographical 

 Society, at its last meeting (December 15), elected the inde- 

 fatigable traveller an Honorary Member. M. Potanin is already 

 at St. Petersburg, and will soon give a lecture on his journey to 

 Western Mongolia, as also M. Pyevtsoff, who travelled with 

 merchants from Biysk to Khou-khoii-khoto, and who during his 

 journey collected much material for the correction of the map of 

 Mongolia. M. Mushketoff, who has explored the glacier of 

 Zaraf-han (NATURE, vol. xxiii. p. 44), gave a lecture at the last 

 meeting of the Russian Geom'aphical Society on his excursion. 

 This traveller, contrary to M. Severtsoff's experience, did not 

 find in the Thian-Shan any traces of the glacial period. 



The Kouban News announces the appearance, in the Sea of 

 Azofif, of a new little island, some 150 feet in diameter, and 10 

 feet above the level of the water. Its appearance was accom- 

 panied with a kind of marine eruption. It is 150 brasses distant 

 from the -hore, wheie a crevice has appeared. 



The organisation of the Polar meteorological station on the 

 Lena is being actively carried out by Prof. Lentz. The director 

 of the station will be M. Vurgens. 



Prof. Nordenskjold is again thinking of fresh enterprises. 

 At present a ship is being built at the Lena estu.ary, in which he 

 intends to start on a new Arctic expedition in the summer 

 of 1882. 



Prince Borghesi-, the Italian African traveller, has arrived 

 near Tripolis from Wadai. This is the first time that a traveller 

 from Darfur has reached the Mediterranean by way of Wadai 

 and Bornu. 



The Leipzig publishing firm of Ferd. Hirt and Son announce 

 that Major Serpa Pinto's great African work of travel will be 

 published in January, 1881. 



