i54 



NATURE 



{^Dec. 21, 1876 



in contact is effected by an interchange in position of 

 indefinitely minute volumes of the gases, which volumes 

 are not necessarily of equal magnitude, being in the case 

 of each gas inversely proportional to the square root 

 of the density of that gas." He speaks of diffusion " being 

 effected by a force of the highest intensity," and insists 

 that diffusion takes place between the ultimate particles 

 of erases, and not between sensible masses. In a later 

 paper, Phil. Trans., 1863, he states that molecules only 

 of gas can pass the pores of graphite, "and they may be 

 supposed to pass wholly unimpeded by friction." He 

 showed that a gas may pass into a vacuum in four ways, 

 first by effusion, a movement which affects masses of gas 

 only, second, by diffusion which affects molecules, third, 

 by transpiration through capillary tubes, " the transpira- 

 tion ratios forming a class of phenomena remarkably 

 isolated from all else at present known of gases," and 

 lastly by a previous absorption in the walls of the septum 

 which divides the gas from the vacuous space, as was 

 so beautifully shown in the papers published in the years 

 1866-69. In one of these, in considering the passage of 

 gas through metallic septa, he recognises "an inter- 

 molecular porosity due entirely to dilatation at a high 

 temperature," and thus apparently hoped to ascertain the 

 ulcimate size of molecules, for he says that this "species 

 of porosity, if it exists, might well be expected to throw 

 light on the distances of solid molecules at elevated 

 temperatures." 



His views are very clearly defined in a paper published 

 in 1863 entitled "Speculative Ideas respecting the Consti- 

 tution of Matter." He is of opinion that the various kinds 

 of matter now recognised as different elementary sub- 

 stances may possess one and the same ultimate or atomic 

 molecule existing in different conditions of movement. 

 Were this ultimate atom at rest, the uniformity of matter 

 would be perfect ; but it always possesses motion, due to 

 a primordial impulse, and, as differences in the amount of 

 this motion occasion differences of volume, matter only 

 differs in being lighter or denser matter. The gaseous 

 molecule is composed of a group of the preceding inferior 

 atoms following similar laws and is thus a reproduction 

 of th3 inferior atom on a higher scale. Chemical com- 

 bination consists in equal volumes of the different forms 

 of matter coalescing and forming a new atomic molecule, 

 and is therefore directly an affair of weight ; and the 

 combining weights differ because the densities, atomic 

 and molecular, differ. Graham is further careful to point 

 out that liquefaction and solidification probably only 

 involve a restriction of the range of the atomic move- 

 ment. 



In this brief sketch it has not been possible to touch on 

 his views as to states of matter, such, for instance, as the 

 " colloidal condition which intervenes between the liquid 

 and crystalline states," or to the more purely chemical 

 portion of his work, of which his theory of polybasic acids 

 is probably the most remarkable. 



Widely as the value of Graham's work was recognised 

 during his lifetime, there is no doubt that the appreciation 

 of it is increasing, and cannot fail to be stimulated by 

 Mr. Young's liberality, which has set forth the researches 

 in such a manner as to impress us with their coherence 

 and strength. 



W. Chandler Roberts 



THE ANDES AND THE AMAZON 

 The Andes and the Amazon; or, Across the Continent of 

 South America. By James Orton, A.M., Professor of 

 Natural History in Vassar College, U.S., &c. Third 

 Edition, Revised and Enlarged, containing Notes of a 

 Second Journey. Maps and Illustrations. (New 

 York : Harper Brothers, 1876.) 



A S is indicated in the title this work contains accounts 

 -^^ of two separate journeys, to a considerable extent 

 over the same ground, the first undertaken in 1867, the 

 second in 1873. A narrative of the former was published 

 several years ago both in America and in England, we 

 believe; the second half of the volume is quite new and 

 is essentially supplementary to the former. The results 

 of the journey of 1867 are given in the form of a personal 

 narrative, those of 1873 are arranged systematically in a 

 number of chapters on the various features cf the Amazon 

 and its surroundings. The main scientific results of 

 both expeditions have been described in the Proceedings 

 of various scientific societies and in scientific journals in 

 America and in England, and the present volume is 

 therefore perfectly free from any details that would prove 

 unattractive to the general reader. 



In the journey of 1867 Prof. Orton and party landed at 

 Guayaquil in Ecuador, mounted the Andes to Quito, pro- 

 ceeded by Papallacta, Baeza, and Archidona, still among 

 the Andes, to the Napo river. Floating down this river 

 they reached the Amazon, took s Learner at Pebas, and 

 enjoyed a splendid sail to the mouth of the river at Pard. 

 In the second journey, that of 1873, Prof. Orton Innded 

 at Para and sailed up the great river to Yurimaguas, 

 thence over the Andes to the Pacific Coast and down to 

 Lima, with a side-excursion to Lake Titicaca by way of 

 Arequipa. 



Prof. Orton tells his story in most attractive style. He 

 is in danger sometimes, no doubt, of degenerating into the 

 florid, but from beginning to end of his large volume he 

 never ceases to be attractive, amusing, and instructive. 

 He writes on people and things in the wonderful region 

 of the Amazon with great piquancy, genuine humour, 

 and full knowledge ; he fretjuently becomes absolutely 

 eloquent, if not poetic. Few features of the towns and 

 the country through which he passed have escaped his 

 attention. In describing his first journey, he lingers at 

 Quito for several chapters, describing the city, giving 

 hints and comments on its history, touching off the ap- 

 pearance and character of its easy-going people, giving 

 an account of the country of which it is the capital, 

 Ecuador, the flora and fauna and primeval inhabitants of 

 the Valley of Quito, rising thence to an eloquent dramatic 

 sketch, a la Hugh Miller, of the geological history of 

 South America, the rise of the Andes, and the creation of 

 the Amazon, devotes two interesting chapters to the 

 volcanoes of Ecuador and its earthquakes, and before 

 leaving, gives several details about a lew of the Indian 

 tribes in " the Province of the Orient." So on his way 

 dov/n the Napo and the Amazon, he paints vividly and 

 picturesquely the scenery, the people, the animals, the 

 plants, and the geology of one of the most interesting re- 

 gions in the world. He chats pleasantly and piquantly of 

 all he comes across, never gives the reader a chance of 

 feeling wearied, and leaves him, if he has been a faithful 



