March 15, 1894] 



NATURE 



457 



species had a breeding-place near which any whaling ship, in 

 the present century at least, ever went ; and those who accept 

 this version recur to errors that were refuted by Prof. Stenstrup 

 more than five-and-thirty years ago. Alfred Newton. 



Magdalene College, Cambridge, March lo. 



The Decomposition of Liquids by Contact with 

 Cellulose. 



The recent work of Dr, Gore, on "The Decomposition of 

 Liquids by Contact with Powdered Silica," presents a striking 

 resemblance to what has from time to lime been ascertained with 

 such substances as cellulose. In fact, the properties ascribed to 

 silica are very likely shared under some conditions by colloids 

 in general, whether they be "organic" or "inorganic" bodies. 

 Cellulose, when imrriersed in diluted solutions of some metallic 

 sails, has the power of abstracting from them a certain quantity of 

 the salt for which it may have no chemical affinity as ordinarily 

 understood. The amount of salt abstracted is dependent upon 

 several conditions : the degree of dilution of the salt ; the 

 ratio of cellulose to salt ; the ratio of cellulose to weight of 

 soluiion : the temperature ; the physical condition of the 

 cellulose; and the chemical constitution of the cellulose. 



Let us, in order to eliminate the last-named condition, con- 

 fine ourselves to pure cellulose or cotton. When cotton wool 

 is placed in a solution of a metallic salt, it abstracts the salt from 

 the solution until equilibrium is established. If we regard 

 ihe'part played by the cellulose in the light of Win's theory of 

 solid solution, the amount of salt retained by cellulose is con- 

 ditioned by the relative solubility of the salt in water and cellu- 

 lose, and the ratio in which the three exist together. If water 

 is now added, a certain amount of the salt dissolved by ihe 

 cellulose will become resoluble in the water. Also, if the 

 solution be concentrated, the fibre will generally take up a 

 fuither quantity. In some cases, however, the amount of salt 

 taken up by the cellulose is not imparted to the solution on 

 dilution. This is probably due, as in the case, I believe, of the 

 ferric salts, to dissociation in solid solution. The dissociated base 

 being insoluble (in water) is retained by the cellulose on addition 

 of water, whereas the acid may be dissolved. The physical con- 

 dition of the same cellulose has a great influence upon the 

 amount of salt which it is capable of dissolving. If cellulose be 

 finely disintegrated, it behaves differently from that in which the 

 ultimate fibres remain intact. 



The cotton fibre, when seen under the microscope, is found 

 to vary considerably in shape and size. It is probable, then, 

 that each fibre has a certain constant of absorption peculiar lo 

 itself. Cellulose, when rendered anhydrous by placing it in a 

 water-bath or desiccator, is found to rise considerably in lem- 

 perature when exposed to a damp atmosphere. This may, how- 

 ever, be caused by the liberation of heat, due to the condensation 

 of moisture from the gaseous state. If so, no rise of temperature 

 would be noticed in plunging anhydrous cellulose into water. 

 It appears, however, that cellulose is susceptible of a certain 

 degree of hydration in coming in contact with water, which is 

 probably attended by the liberation of heat. I have found 

 that dried cellulose placed in a damp atmosphere remains at a 

 higher temperature than its surroundings so long as it is taking 

 up moisture, which appears to be greatest when ihe rate of ab- 

 sorption is greatest. By the time it has recovered its normal 

 condition of moisture it has sunk to the temperature of its 

 surroundings. 



The above considerations seem to point out that cellulose, 

 like silica, exhibits well the phenomena of solid solution. 



C. Beadle. 



Physiological Psychology and Psycho-physics. 



In a note contained in your issue of January u (p. 252), 

 upon the teaching of psycho-physiology in University College, 

 I notice two errors ; which, as they are, unfortunately, very wide 

 spread, you will perhaps allow me to correct. 



(i) "Physiological psychology"' and " psychopliysics " are 

 not one and the same thing. The former science is a specially 

 limited and specially enlarged psychology. Limited : in that 

 it pays more attention to experimentation carried out by physi- 

 ological methods than to any other psychological experimenta- 

 tion. Enlarged : in that it discusses the most important problems 

 relating to the physical basis of mental life. These latter 

 problems belong to psycho-physies, which is the science of the 

 relation of "mind" to "body." 



(2) A " practical course in psycho-physiology," which con- 

 fines itself to the senses, is not a representative or adequate 

 course, as the note implies. The psycho-physics of sensation is 

 no more the whole of psycho-physics than the physiology of the 

 sense-organs is the whole of physiology, or the psychology of 

 sensation, perception, and idea, is the whole of psychology. A 

 historical accident has led to this popular restriction of the term ; 

 but a glance at the literature of the science will show its 

 wrongness. E. B. Titchener, 



Cornell University, February 16. 



Dr. Titchener's criticism of my note strikes me as a little 

 strange. First of all, he objects to my speaking of " physiological 

 psychology or psycho-physics," maintaining that they are dif- 

 ferent, andt'nen proceeds at once to subsume psycho physics under 

 physiological psychology. As a matter of fact, psycho- physics, as 

 understood by P'echner, the coiner of the word, and generally 

 up to quite recent times, does not directly refer to the relation 

 of the organism to psychical phenomena at all, but to the 

 relation between the (extra-organic) stimulus and sensation, 

 though of course this inquiry leads on to two further inquiries : 

 (a) the relation of the extra-organic to the organic process, and 

 {b) the relation of this last to sensation. Miinsierberg and 

 others ro.v use "psycho-physical" for relations generally 

 between neural processes and psychical processes, but the change 

 of meaning is a little confusing. Anyhow, it will be seen that 

 there is no general agreement about the expressions "physio- 

 logical p-ychdogy" and "psycho-physics," such as Dr. 

 Titchener's note suggests. 



I may add that in using "or" rather loosely (as I 

 felt justified in doing in a short note), I did not mean to imply 

 that the two tiranches of inquiry were identical. I wanted to 

 call attention especially to the fact that the course would go 

 systematically over an experimental inquiry into the senses which 

 would necessarily include reference to stimulus, and so psycho- 

 physics, and reference to nerve process, and so physiological 

 psychology. As to Dr. Titchener's second " error," I find him 

 hypercritical. I am well aware that psycho-physiology covers 

 more than the senses, and I think that nothing which I say 

 implies the contradictory of this. There can surely be a prac- 

 tical course on a subject which does not exhaust all divisions of 

 the subject. As a matter of fact, however. Dr. Hill is taking 

 up other branches, as reaction-time experiments. I was content 

 to emphasise the fact that the senses would be systematically 

 examined ; and all who know what psycho-physiology has done, 

 know that by far the larger part of the really fruitful work 

 leading to definite results has been done in the investigation of 

 the senses. The Writer of the Note. 



March 3. 



THE LAST GREAT LAKES OF AFRICA} 



ADMIRABLY translated as it is. this book scarcely re- 

 tains a trace of its previous existence in a foreign 

 tongue ; but although the translator states in the preface 

 that she has slightly condensed the original matter in 

 bringing it to its present form, we believe that much more 

 rigid compression might wisely have been applied. 

 Earlier books have placed later travels in Eastern Equa- 

 torial Africa so prominently before the British reader, that 

 much of the ground which was full of fresh interest when 

 the two gallant Austrians traversed it is now familiar, and 

 its features common- place. Thus a great part of the first 

 volume, detailing the troubles of inexperienced and, per- 

 haps, somewhat imperious Europeans in organising a 

 large caravan at Zanzibar and Pangani, and in crossing 

 the coast-lands and ascending the slopes to Kikuyu, 

 might well have been omitted without lessening the 

 thrilling interest of subsequent chapters. 



The expedition, primarily a sporting one, was also in 

 large measure e.^pioratory, and if the pursuit of big 

 game, and the hairbreadth escapes of the hunters 



1 Discoverj' of Lakes Rudolf and Ste'anie. A Narrative of Count >amuel 

 Teleki's Exploring and Hunting Expedition in Eastern h.quatorial Africa in 

 1887 and 188S. By his companion, Lieut. Ludwig von Hohnel. Translated 

 by Nancy liell (N. D'Anvers). With 179 orig.nal illustrations and five 

 coloured map s. In two vols. (London: Longmans, Green, and Co., 1894.) 



NO. 



1272, VOL. 49J 



