June 3, 1922] 



NATURE 



707 



book has been reissued in a second edition. It offers 

 a brief technical resume of the optical theories since 

 Descartes and Fermat till the present day, a little 

 being also said about ancient European and Indian 

 ideas on the subject. The elastic solid theories, the 

 electromagnetic theory, and the electron theory are 

 passed in review, each treated briefly in mathematical 

 manner, with its virtues and its imperfections exposed. 

 In the second edition there are a few additions, notably 

 on the theory of relativity in so far as it affects optics, 

 and the opinion is expressed that this theory will not 

 " dispose of the physical existence of the etherial model, 

 until a better one can be found, which shall explain 

 the intimate nature of the various concepts of modern 

 physics, corpuscles and negative particles, electric 

 charge and magnetic force, gross matter and gravita- 

 tion, in one comprehensive scheme." 



S. Brodetskv. 



Notes on Inorganic Chemistry. 



Notes on Inorganic Chemistry for First Year University 

 Students. By Prof. F. Francis. Pp. viii + 244. 

 (Bristol : J. W. Arrowsmith, Ltd. ; London : Simp- 

 kin, Marshall and Co., Ltd., 1921.) 8^. 6d. net. 



THE reputation which Prof. Francis has gained 

 as a teacher is so firmly established that a 

 book written by him on the lines that he has adopted 

 for his lectures may be expected to be of much interest 

 and value. Although the " Notes " have been written 

 primarily for students of Bristol University they will, 

 no doubt, be found useful by many others. 



The book commences with a few interesting extracts 

 of a philosophical nature from the works of various 

 authors and a brief note on the indestructibility of 

 matter ; the subject of errors is then fully discussed, 

 and the laws relating to gases are considered at length. 

 The properties of hydrogen and oxygen are next de- 

 scribed together with those methods of preparation 

 which are of practical or theoretical importance. 

 Opportunity is thus afforded for reference to catalysis, 

 autoxidation, and the methods of determining the 

 relative atomic weights of these two elements. The 

 next three chapters are devoted to a discussion of the 

 chemical atom, energy, thermochemistry, and to a 

 fuller account of catalysis. In the chapters on the 

 physical properties of water, a variety of subjects are 

 discussed, such as vapour pressures and boiling points, 

 the phase rule, solutions, osmotic pressure, electrolysis, 

 dissociation, and the electron theory. The utilisation 

 of atmospheric nitrogen in the preparation of ammonia 

 and nitric acid is considered in some detail and the 

 natural sources of these substances are mentioned. 

 Reference to the action of sulphuretted hydrogen on 

 NO. 2744, VOL. 109] 



arsenious acid serves as an introduction to a brief 

 discussion of the chemistry of colloids, and in the 

 remaining chapters Dulong and Petit's law, the periodic 

 law, the laws of constant composition and of multiple 

 proportions, the law of isomorphism, and the subject 

 of valency are discussed. 



The book is for the most part very clearly written, 

 but typographical errors are rather numerous : for 

 example (p. 9), 3-i4i5^'' = 93,621, not 93-621 ; (p. 21) 

 P should read p ; (p. 36) for Nitrogemn read Nitrogen ; 

 (p. 44) Lavoisier's name appears in place of Scheele's ; 

 (p. 56) for " proportional now " read " proportional. 

 Now " ; (p. 97) -62%, etc., should be 62%, etc. ; 

 (p. no) for Ladenberg read Ladenburg ; (p. 179) for 

 HCIO4 read HCIO3 ; (p. 205) the formulae for apatite 

 and vanadinite require correction ; (p. 207) in the 

 italicised sentence, " of " should read " or " and 

 " methods " should read " molecule " ; (p. 226) the 

 constant w does not appear in the formula. 



No doubt these mistakes will be corrected when a 

 secbnd edition is required. 



There are a few statements which appear to be open 

 to objection : On p. 23 Dalton's law of Partial 

 Pressures is stated thus: "If P = total pressure and 

 V = total volume, 





It is not stated, however, that the second equality only 

 holds if the volumes are all calculated at pressure P. 



In the thermochemical equations on p. 57 it would 

 perhaps be better to write JHg rather than H where 

 molecular and not atomic hydrogen is meant. 



On p. 65 there is the statement that " at 0° C. and 

 4 mm. pressure, IceF=^Water-^Vapour." Presumably 

 " ^Vapour " is intended, but, in any case, the triple 

 point pressure of water is 4-6 mm., and at 0° C. and 

 4 mm. pressure water could only exist as vapour. A 

 correct statement would be : " at 0-0075° and 4-6 mm. 

 pressure 



xWater 



NVVapour. 



It is stated on p. 88 that " one gm. molecular weight 

 of Methyl Alcohol, 32-03 gms., dissolved in 1000 gm. 

 of water raises the Boiling Point to ioo°'52 " ; but, 

 of course, all mixtures of methyl alcohol and water 

 boil at a lower temperature than pure water. It is 

 evidently assumed that methyl alcohol is practically 

 non-volatile. 



The following sentence occurs on p. 204 : " atomic 

 weight of Sulphur : atomic weight of Selenium = 18-39 • 

 45-34 of Sulphur = 32." Presumably the words "of 

 Sulphur = 32 " should be deleted. There is also a 



