228 Georye Frederic Barker. 



"By classifying thus tiie substances known as acids and bases, 

 — and, of course, the salts derived from them — it is hoped that 

 their relations to each other may be made clearer. And by 

 giving them systematic names, their position in the series may be 

 fixed, and a step taken toward the establishment of a national 

 nomenclature." 



In 1870, ap])eared his text-book of "Elementary Chemistry, 

 Theoretical and Inorganic," which ran through many editions 

 as well as translations into other languages. This was the first 

 book in our language in which modern chemistry was presented 

 systematically. The style of the book, as so many can testify 

 from its study, is concise and clear. Wolcott Gibbs spoke of 

 it as " a book wholly in the spirit of the most advanced 

 thought in the science." i 



During his life at New Haven, he contributed a note " On 

 the spectrum of an Aurora which appeared at New Haven, 

 November 9, 1871." The point of particular interest in this 

 observation v^as the fact that the line of wave-length, 502, was 

 not laid down in any authority accessible to the observer, as 

 having been noted in the spectrum of the aurora. He adds : 

 " Indeed, no previous observer, so far as I know, has seen any 

 auroral line between the Frauenhofer lines h and F" (this 

 Journal (3), ii, 465, 1871). Sometime later, he presented a 

 second contribution " On the Spectrum of an Aurora of October 

 24, 1872." This aurora, like that of 1871, was distinguished 

 by its radiant crimson color, and by its form. Dr. Barker 

 remarks that in the lines that appeared in the spectrum, noiie 

 was new, though no previous observer had seen all of them 

 at once. Yogel had seen five and four had been seen by Dr. 

 Barker. Two of the lines nearlj' coincided with the solar lines 

 F and G, but a considerable difference was observed in the 

 spectrum of this aurora and that of 1871, for three lines of the 

 aurora of 1872 had no corresponding line in the spectrum of 

 the aurora of 1871. 



Dr. Barker was assistant to Dr. Bacon in the Harvard Med- 

 ical School from 1859 to 1861 ; Professor of Chemistry in 

 Wheaton College, Illinois, 1861 ; then in the Albany Medical 

 College, where he received the degree of Doctor of Medicine 

 (1862-1863), making while there a chemical examination of the 

 viscera of a dead body, the first time it had ever been done in 

 this country ; next, in the University of Pittsburg (1863) ; he 

 also delivered the lectures on Chemistry at Williams College 

 in the years 1868 and 1869 ; and, after service in his Alma 

 Mater, to which reference has already been made, he became 

 Professor of Physics in the University of Pennsylvania (1872), 

 where the remainder of his life was spent. At this period he 

 published a contribution of considerable length, with the aid 



