January 4, 1894] 



NATURE 



2 19 



record of our general knowledge of the subject, exhibit- 

 ing a tolerably complete grip of all the circumstances 

 attending these phenomena. It does not show much 

 originality, perhaps, but it does show very extensive 

 reading, accurate observation, and power of condensa- 

 tion. 



The third book mentioned is scarcely of the kind that 

 compels one to sit down and read off-hand. It is pre- 

 cisely what it professes to be— a collection of the many 

 weather proverbs which possibly the wit of one, rather 

 than the wisdom of many, has perpetuated.- If these 

 adages did contain the results of long-sustained and well- 

 directed observation of the habits of birds, animals, and 

 insects, they would possess a distinct value, though it is 

 difficult to see how the information so gleaned could 

 indicate the severity or the mildness of the coming 

 season ; but it is to be feared they too frequently record 

 the opinion of one who is capable of a jingling rhyme, or 

 of one whom his comrades consider to be wise in such 

 matters. 



There are also quotations from the poets, ancient as 

 well as modern, and all bearing on the subject of weather 

 prediction. The hope of the author is that the perusal 

 of such a collection may induce students to take more in- 

 telligent notice of meteorological conditions, and to avail 

 themselves of accurate instrumental means, rather than 

 to rely upon hackneyed quotations. A somewhat similar 

 collection of " wise saws" was published by the United 

 States Signal Service, but we fail to see any reference to 

 this work in Mr. Inwards's introduction. A study of these 

 sayings would probably furnish some additional quota- 

 tions, and as the compiler aims at greater completeness 

 in the next edition, we would refer him to this source. 

 The book is well printed and admirably " got up," and 

 will no doubt be welcome to many interested in folk and 

 weather lore. 



PH YSICO- CHE MICA L MEASUREMENTS. 

 Hand- unci Hi If sb itch ziir Aus/iihrun^ physiko-chemis- 

 cher Messungen. Von W. Ostwald. (Leipzig : W. 

 Engelmann, 1893.) 



THIS manual must be regarded as the only guide to 

 measurements in physical chemistry which has 

 yet been published. The book is not intended to com- 

 pletely cover this field of investigation, but has evidently 

 been devised with the primary object of assisting Prof. 

 Ostwald in his course of instruction at Leipzig. It is 

 not an introduction to the subject, as the detail supplied, 

 both in connection with apparatus and methods, is insuffi- 

 cient for the requirements of the beginner ; nor is it a 

 treatise wherein a representative collection of methods 

 may be consulted. The book is rather to be viewed as 

 an aid to the teacher, or as indicating to the chemist or 

 the physicist methods which for the most part the author 

 has found to be of service in his own laboratory. 



The information contained in the opening portion of 

 the volume is of the kind usually met with in a physical 

 text-book : modes of calculating results, the influence 

 of errors, the use of corrections, the measurement of 

 length, the balance and weighing, and the measurement 

 and regulation of temperature. Succeeding chapters 

 NO. 1262, VOL. 49] 



take up the more common operations in glass-working, 

 the measurement of pressure, the measurement of the 

 volume and density of solids and liquids, and the 

 ordinary methods of measuring vapour density. Here it 

 may be noted that Perkin's modification of Sprengel's 

 pyknometer, which is perhaps the most useful of all 

 the various patterns, is not included among those de- 

 scribed. Kopp's pyknometer also is rendered more 

 serviceable if a short mm. scale instead of a single mark 

 be etched on the neck. 



The thermal properties of liquids are next briefly con- 

 sidered. Modes of determining expansion and mole- 

 cular volume at the boding-point are given with a 

 moderate amount of detail. The determination of the 

 boiling-point itself is, however, described in the most 

 meagre way. Of the various methods of measuring 

 vapour pressure the dynamical process introduced by 

 Ramsay and Young alone finds a place. Critical tem- 

 perature and critical pressure are determined in separate 

 pieces of apparatus in the manner recently described by 

 Altschul. No general method is indicated whereby the 

 relation between pressure and volume maybe determined 

 under varying conditions of temperature, and no practical 

 method can thus be given for estimating critical volume, 

 although the principle of the new method due to Mathias 

 is mentioned. 



Calorimetry is now dealt with, and short accounts are 

 given of the simpler methods of estimating specific 

 heat and the thermal changes accompanying vaporisa- 

 tion, dissolution, combustion, and reactions in dilute 

 solution. 



Descriptions of optical measurements relating to refrac- 

 tive indices, spectroscopy including spectrum photometry, 

 calorimetry, and rotatory polarisation are now introduced, 

 and are followed by a chapter on viscosity and surface 

 tension. In connection with viscosity, the apparatus repre- 

 sented is only adapted for obtaining relative values, and is 

 quite unsuited for investigating the effect of temperature. 

 What appears to be the correct value of the kinetic 

 energy correction used in calculating viscosity co- 

 efficients is ascribed to Finkener and Wilberforce, 

 whereas the first published account of the mode of deduc- 

 ing it is due to Couette. None of the methods given for 

 measuring surface tension are free from the objection 

 that air is in contact with the liquid surface. 



The remaining chapters are devoted to measurements 

 on solutions. Methods of estimating the solubility 

 of solids, liquids, and gases, and of determining 

 molecular weights from the freezing-points and boiling- 

 points of solutions are given at considerable length. 

 At still greater length, and thus in marked contrast 

 with the treatment elsewhere, electrical measure- 

 ments are next set out. Here are found accounts of 

 the methods of measuring electromotive force and con- 

 ductivity, dissociation constants, the basicity of acids, 

 &c. The last chapter takes up elementary problems in 

 chemical dynamics relating to the velocity of chemical 

 change, the catalysis of methyl acetate and the inversion 

 of cane-sugar by ddute acids being given as examples. 



From whit has been said it is evident that the 

 operations dealt with in the book are only such as are 

 frequently perlormed, or which at the present time are 

 considered to be of importance. Some of these even are 



