Febkuakt 4, 1910] 



SCIENCE 



199 



molecule of an asymmetric atom — of carbon, 

 nitrogen, sulphur, selenium, tin or silicon. 

 In this form the statement is quite incorrect. 

 As was shown by van't Hoff and Le Bel years 

 ago, the optical activity originates in the 

 enantiomorphous configuration of the molecule, 

 which is conveniently recognized by the iden- 

 tification of a particular atom in the molecule 

 as being asymmetric. 



Experimental confirmation of van't HofF 

 and Le Bel's views has been recently furnished 

 by Professors W. H. Perkin, W. J. Pope and 

 O. Wallach' in an extremely valuable and 

 lucid paper which they have contributed to 

 the Journal of the Ohemical Society (Lon- 

 don), 



In 1906, Perkin and Pope sjmthesized 

 l-methylcyclohexylidene-4-aeetic acid. 



(&) CHas^ /CHo— CH,v 



/H (c) 



(a) H^ ^CH,— CH/ ^C0,H (d), 



which contains no asymmetric carbon atom. 

 At first some doubt was expressed as to 

 whether the acid did actually conform to the 

 formula given, but subsequent work has 

 amply confirmed its constitution and it has 

 now been possible to resolve the acid into a 

 dextro- and a Isevorotatory modification, by 

 repeated fractional crystallization of its 

 brucine salt. 



The racemie acid melts at 66°, the optically 

 active acids melt at 52.5-53° ; in absolute al- 

 cohol the specific rotatory power [a]D) is 81.4° 

 and — 81.1°, for the d- and Z-acid, respect- 

 ively. When mixed these acids regenerate the 

 racemie acid of higher melting point. 



Referring again to the formula given above, 

 if the linkages represented by unbroken lines 

 are supposed to occupy the plane of the paper 

 and if those represented by broken lines lie in 

 a plane perpendicular to the first, it will be ob- 

 served that the plane which contains the con- 

 tinuous line bonds is not a plane of symmetry 

 of the solid configuration, because the groups 

 marked (a) and" (I) are different. Similarly, 

 the vertical plane mentioned above is also not 

 a plane of symmetry, because the groups (c) 



'Jour. Ghem. Soc, 95, 1789, 1909. 



and (d) are of different composition. In 

 short, even when the usual tetrahedral sym- 

 metrical configuration is attributed to meth- 

 ane derivatives, the relatively simple acid 

 formulated above is found to possess neither 

 planes, axes nor a center of symmetry, and it 

 is this which determines the enantiomorphism 

 of its configuration. 



The original paper will richly repay 

 perusal; it is written in the clear and inter- 

 esting manner characteristic of Messrs. 

 Perkin and Pope's communications, and it 

 contains a most instructive account of the 

 great experimental difficulties which had to be 

 overcome before this most important work 

 could be brought to a successful issue. 



J. Bishop Tingle 



McMaster Univeesity, 

 ToEONTA, Canada 



IS^COMES OP COLLEGE GRADUATES TEN 

 TEARS AFTER GRADUATION 



The class of '99, Dartmouth College, has one 

 hundred living members in the following oc- 

 cupations: Business, 25; teaching, 23; medi- 

 cine, 14; law, 13; engineering, 10; journalism, 

 2; railroading, 2; farming 2; study, 2; clergy- 

 man, 1; chemist, 1; mining, 1; librarian, 1; 

 unclassified, 3. 



The class might be called average. Some 

 were poor, and some were able to live com- 

 fortably in college, but every one has had to 

 make his own way in his profession. At the 

 decennial reunion last June, and by mail 

 shortly afterwards, reports were received from 

 sixty-seven of the men stating their incomes 

 for the preceding year. The thirty-three from 

 whom no facts were received are probably 

 getting less income than the average of the 

 class, but I do not think they would lower the 

 average greatly. 



The results show an income considerably 

 higher than was thought by those whom I 

 have consulted as to the probable income. 



Looking at the plots we see that five men 

 get less than $1,000, with an average of $832 ; 

 fourteen men from $1,000 to $1,500, with an 

 average of $1,209; eighteen from $1,500 to 

 $2,000, with an average of $1,689; thirteen 



