530 



NA TURE 



\_Oct. 7, 1880 



schools and colleges, and we trust that when another 

 decade's work of the London or any other School Board has 

 to be summarised, the so-called extra subjects will have 

 become an integral part of the elementary education of 

 the country. Such institutions as that opened at Birming- 

 ham will greatly help on the cause of scientific education. 

 The standard of teaching we are glad to see is high, the best 

 science schools of the Continent being taken as models ; 

 and we trust the Mason College will never degenerate 

 into a mere technical training-school. Under the liberal 

 principles for its conduct laid down by the founder, it is 

 capable of the widest development in every direction ; 

 whether it may form the nucleus of a Birmingham Uni- 

 versity remains to be seen. Its working will be watched 

 with the greatest interest by all who have at heart the 

 raising of the standard of education in the country. 



CHEMISTRY OF THE CARBON COMPOUNDS 

 Elements ofCJiemist>y. By William Allen Miller, M.D., 

 &c. Revised and in great part re-written by Henry E. 

 Armstrong, Ph.D., F.K.S., and Charles E. Groves, 

 F.C.S. Part III.— Chemistry of Carbon Compounds, 

 or Organic Chemistry. Section I.— Hydrocarbons, 

 Alcohols, Ethers, Aldehydes, and ParafSnoid Acids. 

 Fifth edition. (London: Longmans, Green and Co., 

 1880.) 



''pHE study of the laws governing the combinations of 

 -*• molecules containing carbon is of the verj' first 

 importance to chemical science, inasmuch as this study so 

 well illustrates and extends the general laws of molecular 

 combinations, that is to say, the general laws of the 

 science of chemistry. 



An almost innumerable array of facts concerning 

 carbon compounds is to be found in the ordinary 

 text-books ; papers in the chemical journals sometimes 

 contain generalisations drawn from certain classes of those 

 facts: the later supplements to Watts's "Dictionary" 

 contain the more important of the comparatively recent 

 generalisations ; but there has undoubtedly existed for 

 some time among students of chemistry a wish for a text- 

 book in which the leading facts concerning the com- 

 pounds of carbon should be clearly stated, the general 

 properties of, and general relation between groups of 

 these bodies should be indicated, and summaries of the 

 evidence in favour of or against the generally adopted 

 structural formula of the more important compounds 

 should be presented to the student, in order that he might 

 thus have in one text-book such a fair compendium of 

 the present state of this branch of the science as should 

 furnish him with suggestions for work, by showing him 

 what is clearly known, where exact knowledge ceases, and 

 where even analogy lends but little help. 



The first part of such a text-book English chemistry 

 now possesses ; let us hope that the second part of this 

 admirable book will soon follow, and be worthy of that 

 now pubhshed. 



In their preface the editors— had we not better say at 

 once the authors ?— write : " Notwithstanding the extra- 

 ordinary increase in the number of the carbon compounds, 

 their study is gradually becoming simplified as the possi- 

 bility is extended of arranging them in series and of 



giving a general description of their chief properties 

 applicable to all the members of the group." 



There can be no hesitation in saying that the authors' 

 work— more than any other text-book in the English 

 language— will aid the advance of this, the only true 

 method, of studying Organic Chemistry. 



There are text-books of Organic Chemistry which tell 

 the student that the structure of this or that compound "is 

 represented by the following formula" ; this book follows 

 another and a better plan : the authors give a succinct 

 and clear sketch of the evidence for and against all 

 important structural formula;, thus indicating the true 

 value of these formute as condensed statements of che- 

 mical facts, and at the same time setting before the 

 student examples of the application of the chemical 

 method of inquiry. 



The general principles underlying the formation of 

 so-called structural formute are adverted to in more than 

 one place by the authors. 



These formula: are based on the laws of "atom- 

 linking," which again are deductions from the theory 

 of quantivalence or valency, itself an outcome of the 

 application of chemical methods of inquiry to the mole- 

 cular theory of matter. 



Although the volume before us is Part III. of a large 

 v.ork, the first part of which deals with chemical physics, 

 it would nevertheless, we think, have been advisable to 

 have given a brief sketch of the molecular theory of 

 matter, and to have shortly stated— but more fully than 

 is done on p. 42— the evidence on which is based the 

 (chemically) all-essential difference between atom and 

 molecule. 



A little space might have been spared for an exposition 

 of the laws of atom-hnking, such as, but very much more 

 condensed than, that in Lothar Meysr's " Modernen 

 Theorieen." 



In speaking of quantivalence, on p. 42, the authors do 

 not explicitly state that it is the atoms of the elements 

 which "are equivalent in combining or replacing power 

 to one, two, three, four, five, or six monad atoms of 

 hydrogen." Of course this is implied throughout the dis- 

 cussion which follows, but students sometimes fail clearly 

 to grasp the difference between the old chemistry, which 

 attempted, but failed, to determine equivalent weights of 

 elements, and the new, which is so largely based on the 

 equivalency of groups of atoms of the elements. 



Frankland's "bond" explanation of valency is sketched, 

 but so long as we have no definite physical conception 

 of what a " bond " is, this explanation really explains 

 nothing; such an expression as "two of the bonds neutral- 

 ise each other" has no meaning, further than that the 

 valency varies from a given number to two less than this 

 number. 



The authors give some examples of compounds, which 

 seem to show that the valency of certain elementary 

 atoms may vary from an odd to an even number ; but 

 they do not give examples which prove such a variation, 

 e.g., M0CI5 and MoCle ; WClj and WClo; NO, NO2, and 

 NH3. 



The authors, probably wisely, do not very definitely 

 express their opinion as to the exact meaning of a 

 sti-uctural formula ; they sometimes appear to regard 

 these formula; as real representations of the relative 



