190 



NATURE 



[Dec. 25, 1879 



Prof. Nordenskjold, before his departure, received from his 

 Excellency, as a present to the Vega expedition, an herbarium of 

 the plants 'of Hongkong and South China, prepared by Mr. 

 Ford, the head of the Botanical Department of the Colony. 



Zanzibar advices report that the Abbe Debaize, the French 

 explorer, was on the 13th of June at Ujiji, on Lake Tanganyika. 

 He was waitin"' for some boats to go to the north of the lake, 

 and meanwhile was examining neighbouring rivers and some 

 points on the lake. At the beginning of September he expected 

 to start for the Uzige country, there to leave a depot of mer- 

 chandise under trustworthy men while he proceeded with the 

 rest of his effects to Aruwimi or Stanley river, which joins the 

 Congo, leaving there a second depot, exploring with his best men 

 the western slope of the Blue Mountains and the region between 

 Lakes Albert and Tanganyika, and then returning to Uzige to 

 despatch reports and explain his further plans. 



The enlarged edition of Whitaker's Almanack for 18S0 con- 

 tains an article on geographical discovery, written in a somewhat 

 perfunctory manner. As instances of the want of proportion 

 observable in it, we may mention the space given to the voyage 

 of the Isbjbrn to Novaya Zemlya, and Mr. McCarthy's journey 

 across China, the former of which was admittedly unsuccessful, 

 while the latter, which did not occur in the period under review, 

 added nothing whatever to our geographical knowledge. Ac- 

 curacy hardly appears to be the mitefsfortg, otherwise he would 

 hardly discourse about Mr. E. Colborne Bauer's journey in 

 Western China, nor would he turn one of the Portuguese African 

 explorers' names into Ives, not to mention his inability to make 

 up his mind how to spell Thibet. 



In the course of their explorations last year in the unknown 

 highlands of Eastern Perak, a party of Englishmen met with 

 several small settlements of Sakis, presumably the aborigines of 

 the peninsula, who still hold themselves aloof from the Malays. 

 Few of these people have metal or earthenware cooking utensils-, 

 but roast their sago in large bamboos. The majority of them 

 speak Malay, with an accent not unlike the Chinese ; their own 

 language is described as soft and guttural. Two specimens of 

 these people— a man and a woman — on being measured, were 

 found to be 4 feet 6 inches and 4 feet t inch in height, and these 

 appeared to be about the average. The women are said to be 

 not bad-looking, with thick lips and flat noses ; their figures are 

 good, though rather inclined to stoutness ; and they have re- 

 markably pretty little feet and hands. The dress of both sexes 

 consists of a strip of bark about 9 feet long and I foot 6 inches 

 wide, wound round the bodies. The bark used is that of a 

 species of fig, and is very soft and pliable ; there are two descrip- 

 tions of it, obtained from different trees, one of a dirty while 

 and the other of a reddish brown colour. 



The new number of the Bulletin of the Societe Conimcrciale 

 de Geographie of Bordeaux, contains an article on Cabul, and 

 from its " Chronique Geographique " we learn that the French 

 Minister of Marine has ordered the Governor of Senegal to send 

 an expeditionary column to the country between the Upper 

 Senegal and the Niger. The object of the column will be to 

 explore the region in order to see by actual survey and examina- 

 tion whether the two rivers can be joined by a railway. The 

 expedition will be accompanied by a skilled topographer. 



Mr. H. Conybeare, of the Bengal Civil Service, has pub- 

 lished a carefully prepared report on the Pargana Dudhi, which 

 extends from 25" 52' 17" to 24° 21' 21" N. lat., and from 

 82° 59' 28" to 83° 28' 7" E. long. The first portion deals almost 

 entirely with geographical matters, and furnishes much interest- 

 ing information respecting the various aboriginal tribes, their 

 language, customs, and style of cultivation, &c. 



The Hiogo News states that the Japanese Government has 

 decided upon at once going on with the construction of a rail- 

 way between Shiwotsu, at the head of Lake Biwa, and Tsuruga, 

 a town at the head of a large bay, which will probably before 

 long become an open port. Some high officials connected with 

 the Board of Works are to proceed to Tsuruga on this business 

 without delay. It is expected that the opening of the line in 

 question will have a most beneficial effect on the trade of the 

 treaty port of Kobe. A large extent of rich country will be 

 opened up to commerce, and it is probable that the whole of the 

 produce of the silk districts to the north of Lake Biwa will be 

 brought to Kobe for shipment to Europe. 



ON THE NATURE OF THE ABSORPTION OF 



GASES 

 AT ORE than seventy years ago Dalton made the assertion that 

 ■'■•'- gases, when absorbed by liquids (e.g., water), remain only 

 mechanically included in the latter, without losing thereby any 

 property which belongs to them as gases. This hypothesis of the 

 nature of absorption is opposed by a still older one — the chemical 

 — which considers the phenomenon as the consequence of an 

 affinity between gases and liquids, and explains, for example, the 

 absorption of C0 2 and N 2 by water by the formation of H 3 C0 3 

 and HNO. Since the time when these two hypotheses were 

 started, their proofjj has jalways been attempted with the aid o f 

 the statical method ; i.e., by the determination of the proportion 

 in which the absorbed and absorbing bodies maintain their equi- 

 librium under given conditions ; or, in other words, by the deter- 

 mination of the coefficients of absorption. Mackenzie, who in 

 this way has lately most thoroughly examined into the absorption 

 of carbonic acid by means of a solution of salt in water, says that it 

 would be presumptuous, on the basis of existing observations, to 

 attempt yet to solve the problem whether absorption is a purely 

 physical phenomenon or whether it belongs rather to the domain 

 of the so-called chemical phenomena. 



After these two hypotheses there comes yet a third, set forth 

 by Graham, according to which gases are transformed into the 

 liquid state in the case of their absorption by bodies such as 

 liquids, caoutchouc, or by glowing metals. This hypothesis 

 is supported on the one hand by the circumstance, already 

 remarked by Mitchell, that membranes of caoutchouc are most 

 easily penetrable for those gases which are most readily capable 

 of being rendered liquid and are most soluble ; on the other, by 

 two assertions of Graham's— (1) That a body in the form of a 

 liquid penetrates another body more easily than in the form of a 

 gas ; and (2) That liquids and such colloid substances as caout- 

 chouc, have no pores at all, and, in point of fact, are, even 

 in the thinnest film, impenetrable, to gas;s as such. Accord- 

 ing to Graham, then, it is impossible tor a gas to penetrate 

 such a substance without this conversion into a liquid state, 

 which may or should be favoured in some measure by the 

 chemical affinity between the gas and the absorbing substance. 



My researches in the domain of diffusion gradually led me 

 to the conviction that a much nearer approach will be made 

 to a solution of the problem of absorption if conclusions 

 are drawn, with reference to the state in which gases exist in 

 these substances from the study of the phenomena of motion, 

 which exhibit them in their diffusion through absorbing substances. 

 Availing myself of the kind invitation of the editor of Nature, 

 I shall take the liberty of here briefly describing the results which 

 I have in this way obtained. They refer to what takes place in 

 the case of caoutchouc. 



The application of the laws of the diffusion of gases through 

 absorbing substances 1 to the phenomena which appear in caout- 

 chouc shows that the quantity of gas which passes through a 

 membrane of caoutchouc in a unit of time is, conditions being 

 equal (i.e., equal surfaces of diffusion, equal thickness of the 

 membrane, and equal difference of saturation on both sides 

 of the membrane) in proportion to the product D S. D is the 

 constant of diffusion of a gas in caoutchouc, and corresponds to 

 the thermometric conductivity of a body in the theory of the 

 conduction of heat. ^ is the coefficient of saturation, and is 

 expressed by the equation — 



8 76 

 in which A„ denotes the coefficient of absorption of caoutchouc 

 for the gas under consideration at the temperature 6, and 

 / the pressure (in centimetres of mercury) under which the 

 gas is. The coefficient, then, is that volume of gas reduced to 

 o° C. and under 76 cm. of mercury which can be contained in the 

 unit or volume of caoutchouc at the given temperature and under 

 the given pressure. It corresponds to the specific heat of the 

 unit of volume of a substance in the theory of heat. 



Mitchell and Graham, during their experiments with caout- 

 chouc, have always measured the product D S only, which can 

 give us absolutely no explanation of the nature of the absorption 

 of gases, and which has led Graham, as we shall see farther on, 

 to false inductions. 



In order to determine the constant D, which shall form the 



basis of our examination, it is necessary to know the coefficient 



of absorption, by means of wdiich the coefficient of saturation 



1 Wroblewski in Wiedemann's Annalin, ii., 481-513. , 



