November io, 1904] 



jVA TURE 



29 



— this forming, perhaps, the best portion of the book. 

 After three experiments in gravimetric work the learner 

 passes on to systematic qualitative analysis, treated 

 from the standpoint of electrolytic dissociation. The 

 author recognises that, " logically," the quantitative 

 work should follow rather than precede the qualitative ; 

 but after repeated trials he prefers the order indicated. 

 In the present connection, however, the matter is more 

 one of convenience than of logic. 



Accepting the author's system, the experiments 

 themselves are judiciously selected, and well fitted for 

 their purpose. But there are educationists who would 

 by no means agree that " theoretical explanations 

 should be reserved for the recitation-room," and not 

 given in the laboratory. Still less would they say that 

 the students should " study thoroughly all the details 

 of an experiment before attempting to perform it," and 

 that "this should be done outside the laboratory." 

 Whether such a system would tend to produce a hod- 

 man or an architect would depend, as it seems to the 

 writer, less upon its own merits than upon the 

 personality of the instructor. C. S. 



D/e Einheit der Naturkrafte in der Thermodynamik. 



By Richard Wegner. Pp. viii+132. (Leipzig: 



Von Veit and Co., 1904.) 

 As described in the secondary title, this pamphlet is 

 an attempt to deduce from the kinetic energy of non- 

 elastic atoms, corporeal and ethereal, all known 

 physical forces, chemical, electrical, and mechanical, 

 including gravity. Nothing Boschovichian is assumed ; 

 only the kinetic energy of moving atoms of different 

 sizes. It is not easy to follow an argument which 

 provisionally assumes that the atoms are held together 

 to form molecules with regular vibration frequencies 

 capable of propagating through the surrounding swarm 

 of ether-atoms waves of condensation and rarefaction, 

 by means of the reactions and interference of which 

 (when there are two or more molecules) attractions 

 are brought into being; and which then, in terms of 

 this general outlook, gives reasons why the reaction 

 of the ether atoms may be found sufficient to hold the 

 corporeal atoms together. A necessary consequence 

 of the investigation is that gravity is propagated in 

 time, and should be a function of the temperature. 

 The author has tested the latter point by experiment, 

 and finds some evidence in favour of its truth. The 

 source of the chemical elements is found in the different 

 magnitudes of the atoms, with the corresponding 

 differences in their energetic combinations. The 

 temperature of a body is proportional to the mean 

 molecular weight, multiplied by the square of the mean 

 translational velocity of the molecule ; divided by the 

 relative number of molecules in unit volume ; multiplied 

 by the relative mean path of the molecule. Since, 

 according to the theory elaborated, the kinetic energy 

 of the elementary particles implies attraction, all bodies 

 will be surrounded by a layer of condensed gas and 

 ether particles. In the waves in the ether sheath is 

 found the source of the electrical current. Electro- 

 static action, on the other hand, depends on chemical 

 actions In the ether sheath. The applications to 

 chemical and electrical phenomena are admittedly 

 crude and imperfectly worked out; but the author 

 claims to have proved the possibility of deducing all 

 the recognised forces of nature from the kinetic energy 

 of non-elastic Lucretian atoms. 



The Science and Practice of Photo graphy . By Chap- 

 man Jones, F.I.C., &c. Fourth edition. Pp. 569. 

 (London : Iliffe and Co., Ltd., 1904.) Price 5^. net. 

 This volume, which is the fourth edition of the work, 

 has been very greatly enlarged and rewritten since the 

 appearance of the third edition, the number of chapters 



NO. 1828. VOL. 71] 



having been increased from fifty-five to sixty-eight. 

 It may be considered as forming a most excellent guide 

 to the practice of photography, and a perfect reference 

 for those who so continually question one as to " the 

 best book on photography, for a beginner, you know " ; 

 and it will doubtless prove useful as a reference book 

 to many who have long passed the beginner stage. 

 There is a decision of tone and clearness of exposition, 

 combined with an intelligent anticipation of the many 

 questions which arise at every step of the path, which 

 render it especially suitable for this purpose. 



At the same time, the scientific reader who hopes 

 to gain from it some account of the work which has 

 been done of late years, with a view to the clearing 

 up in some measure of the chemical and physical 

 problems in which photography abounds, will probably 

 be greatly disappointed. The two most noteworthy 

 features of this, as of almost all English works on 

 photographic science, are found in the method in which 

 contemporary German literature is ignored, and in 

 which the whole of modern physical chemistry is dis- 

 regarded. The fact, for instance, that development 

 may be regarded as a reversible heterogeneous re- 

 action occurring between ionised salts, in accordance 

 with the mass law, seems to be entirely beyond the idea 

 of this or any other book on the subject. Development 

 with ferrous oxalate is here represented by the 

 equation : — 



3AgBr+ 3FeC,0, = FeBr^ + Fe2(C„OJ, + 3Ag, 

 which, involving as it does the existence of ferric ions 

 in the developer after use, gives a sufficiently distorted 

 view of the reaction. While we find the chemical 

 theory of the book to be of this type, the information 

 as to the progress of sensitometrv' is of the slightest, 

 no mention whatever being made of the notable re- 

 searches by Dr. Eder. A most original suggestion as 

 to the nature of the developable condition is to be 

 found at the close of the chapter devoted to that sub- 

 ject. In brief, this book is a most delightful manual 

 of the practice of photography, but can scarcely claim 

 to represent the scientific side of the subject in any 

 sense whatever. C. E. Kenneth Mees. 



Ants and Some Otiier I)isccts. An Inquiry into the 



Psychic Powers of tliese Animals. With an Appen- 



di.x on the Peculiarities of their Olfactory Sense. 



By Dr. August Forel. Translated from the German 



by Prof. William Morton W'heeler. Pp. 49 ; figures. 



(Chicago, 1904.) Price 2S. 6d. 



An elaborate treatise on the senses of insects, especially 



ants, illustrated by numerous experiments. The book 



deserves the most serious attention of students of 



psychology and animal intelligence ; but it would 



occupy too much space, nor would any useful object 



be gained, by attempting to epitomise either the body 



of the work or even the author's deductions. We may, 



however, quote the following conclusions ; — 



" Even to-day I am compelled to uphold the seventh 

 thesis which I established in 1877 in my habilitation as 

 privat-docent in the University of Munich : 



" ' All the properties of the human mind may be 

 derived from the properties of the animal mind.' 

 " I would merely add to this : 



" And all the mental attributes of higher animals 

 may be derived from those of lower animals. In other 

 words, the doctrine of evolution is quite as valid in 

 the province of psychology as it is in all the other 

 provinces of organic life. Notwithstanding all the 

 differences presented by animal organisms and the con- 

 ditions of their existence, the psychic functions of the 

 nerve-elements seem nevertheless everywhere to be in 

 accord with certain fundamental laws, even in the 

 cases where this would be least expected on account of 

 the magnitude of the differences." 



