450 



NATURE 



[April 8, 1922 



This suggestion is far from new. Biot himself, as 

 long ago as 1836, produced an artificial anomaly when 

 he attempted to compensate the optical rotatory power 

 of laevorotatory turpentine by means of a column of 

 dextrorotatory oil of lemon. Similar results were 

 obtained with artificial mixtures of turpentine and 

 camphor"; and so long ago as 1858 Arndtsen, after 

 establishing by his own measurements the unequal 

 dispersive power of optically active compounds, made 

 the following suggestions : — 



" If one should imagine two active substances which 

 do not act chemically upon one another, of which one 

 turns the plane of polarisation to the right, the other 

 to the left, and, in addition, that the rotation of the 

 first increases (with the refrangibility of the light) 

 more rapidly than that of the other, it is clear that, 

 on mixing these substances in certain proportions, one 

 would have combinations which would show optical 

 phenomena precisely similar to those of tartaric acid, 

 as M. Biot has already proved by his researches on 

 different mixtures of turpentine and natural camphor. 

 One could then regard tartaric acid as a mixture of 

 two substances differing only in their optical properties, 

 of which one would have a negative, and the other a 

 positive, rotatory power, and of which the rotations 

 would vary in different proportions with the refrangi- 

 bility of the light." 



This suggestion, made more than sixty years ago, 

 can now be supported by two additional lines of argu- 

 ment : (i) the mathematical evidence that the rotatory 

 dispersion of these substances is in fact the sum of two 

 simple rotations — e.g. as expressed graphically by the 

 fact that the complex curves obtained by plotting a 

 against A^ are merely the weighted mean of two rect- 

 angular hyperbolas ; (ii) the chemical evidence that 

 mixtures of isomers do in fact exist, which fulfil the 

 conditions laid down by Arndtsen. Of these optically 

 active " dynamic isomerides " nitrocamphor was one 



of the earliest examples to be studied, and it is still one 

 of the best illustrations that Can be given of this group 

 of phenomena. 



The existence of two forms of nitrocamphor was 

 proved by the discovery of mutarotation — i.e. change 

 of rotatory power with time in freshly prepared solu- 

 tions of the compound ; but a mere trace of a catalyst, 

 such as piperidine at a concentration of M/io,ooo, is 

 sufficient to speed up the isomeric change to such an 

 extent that mutarotation can no longer be detected. 

 In tartaric acid and its esters similar conditions of 

 rapid interconversion appear to prevail, since careful 

 observations have failed to detect any lag of rotatory 

 power after dissolution, dilution, distillation, or fusion. 

 As in the case of nitrocamphor, however, it is possible 

 to recognise, in addition to the usual mixtures, a certain 

 number of derivatives of a fixed or homogeneous 

 character, and these are characterised by opposite 

 rotatory powers and unequal simple dispersions, 

 precisely as we have postulated for the two modifica- 

 tions of the parent acid. Thus (i) tartar emetic differs 

 from the other tartrates not only in showing a much 

 higher rotatory power, but also in giving a dispersion- 

 curve of the " simple " type which is characteristic of 

 the vast majority of optically active organic com- 

 pounds ; (ii) on adding an excess of alkali to tartar 

 emetic a Isevorotatory derivative is produced, but this 

 also exhibits simple rotatory dispersion ; (iii) boric acid 

 also possesses the power of fixing tartaric acid in a 

 dextrorotatory form with simple rotatory dispersion. 



In view of these observations it is difficult to resist 

 the conclusion that tartaric acid, like nitrocamphor, 

 can exist in two forms and yield two types of deriva- 

 tives, and that the presence of these two types is 

 responsible for the complex rotatory dispersion of the 

 acid and of so many of its derivatives. The molecular 

 structure of these two types is a fascinating problem 

 which still awaits investigation. 



Obituary. 



Dr. G. B. Mathews, F.R.S. 



BRIEFLY recorded in Nature a fortnight ago, the 

 death of Dr. George Ballard Mathews occurred 

 in a Liverpool nursing home on March 19. 



Born in London (February 23, 1861), of a Hereford- 

 shire family, Mathews' versatile intellect showed itself 

 during his schoolboy days at Ludlow Grammar School, 

 where the then head master instructed his boys in 

 Hebrew and Sanscrit as well as in Greek and Latin. 

 After a year at University College, London, where he 

 studied geometry under Henrici, and of which body he 

 later became a fellow, he entered St. John's College, 

 Cambridge, which offered him the senior scholarship of 

 his year either in mathematics or classics. Carrying 

 out his intention of reading for the Mathematical Tripos 

 he became a private pupil of Mr. W. H. Besant of 

 St. John's. The keen competition for leading places in 

 the Tripos of this period had brought fame to Mr. E. J. 

 Routh as a coach and all the abler candidates went to 

 Routh as a matter of course, for Routh had a long series 

 of senior wranglers to his credit. However, Mathews' 

 name was read out first in the list of 1883, this being 

 the only break in a succession of about thirty conse- 

 cutive seniors trained by Routh. 



NO. 2736, VOL. 109] 



In 1884 Mathews was appointed to the chair of 

 mathematics in the then newly-constituted University 

 College of North Wales at Bangor, his election to a 

 fellowship at St. John's taking place the same year. 

 His colleagues at Bangor were all of the same genera- 

 tion as himself and included such men as Professors 

 Andrew Gray, James Dobbie, and the late Henry Jones 

 under the leadership of Principal Harry Reichel (the 

 last three named have all since been knighted). The 

 Bangor chair was resigned in 1896, and shortly followed 

 by Mathews' election into the Royal Society and by his 

 return to Cambridge as University Lecturer in Mathe- 

 matics. During this period he was mathematical 

 secretary of the Cambridge Philosophical Society for 

 a time and also served on the Council of the Royal 

 Society and on that of the London Mathematical 

 Society. Resigning the Cambridge appointment in 

 1906 he returned to Bangor and, since 191 1, held a 

 special lectureship in the North Wales University 

 College. The honorary degree of LL.D. was conferred 

 by Glasgow University in 1915, and he again acted as 

 professor of mathematics in Bangor during the two 

 College sessions 191 7-19. Dr. Mathews himself attri- 

 buted the distressing series of illnesses which clouded 



