OLIVER WOLCOTT GIBBS. xxvii 



luteocobalt and roseocobalt. Gibbs in 1852 established the composi- 

 tion of a third and new cobaltamine now called xanthocobalt, and 

 the two American chemists naturally were led to work in concert. In 

 1856 they published their celebrated memoir, describing no less than 

 35 salts of these three cobaltamines, together with some of those of 

 a fourth called purpureocobalt. They gave adequate analyses of 

 these salts, together with crystallographic measurements, by J. D. 

 Dana, of eleven of them. Purpureocobalt was then first dis- 

 tinguished from roseocobalt, though the conception then attained of 

 the precise nature of the difference was not final. Gibbs attempted 

 a discussion of the constitution of these bases, but prematurely. 

 Adequate theories of structure were yet to be developed; when such 

 development came, the facts established by Gibbs and Genth formed 

 a solid foundation for the brilliant superstructure. Eleven years 

 after this paper, Gibbs himself made an attempt to establish the 

 theory of the structure of these amines. The conception utilized by 

 Gibbs was also utilized two years later by one of the leaders in the 

 establishment of the doctrines of structural chemistry; these views 

 have now given way to other views which harmonize better with a 

 wider range of facts ; but the discussion of tentative possible ex- 

 planations of facts is one of the steps by which the truth is finally 

 discovered. Gibbs utilized his hypothesis of the structure of the 

 cobaltamines in further papers in 1876 and 1877, in which he 

 described many more salts, some of these being salts of a fifth amine 

 called croceocobalt. The whole was a great piece of valuable and 

 most fruitful work, carried on with extraordinary ability and 

 success. 



The work on the platinum metals, published from 1861 to 1864, 

 related mainly to analytical methods. In 1871, he published a brief 

 note on a remarkable compound of iridium, and in 1881, he de- 

 scribed a new basic compound of osmium. But these researches 

 had to be discontinued for lack of suitable facilities. 



Gibbs was a man fertile in varied suggestions ; in many a con- 

 versation he would lavish freely material almost sufficient for the 

 working capital of a teacher who taught largely by inspiring and 

 directing research. It was natural, therefore, that besides the great 



