OBITUARY NOTICES. . XV 



on July 21, 1852, Dr. Wolcott Gibbs, then of New York, who had 

 followed Dr. Genth's directions and had prepared these bases in his 

 laboratory, wrote him as follows : " I enclose you herewith a small 

 quantity of my orange-cobalt compound. . . . Please let me have 

 your opinion of it. I think it identical with yours. Let me urge 

 you to go on with your investigation, as it must lead to very inter- 

 esting results independently of the beauty of the compounds in 

 question." Dr. Genth's response must have been prompt, for in 

 a second letter, written on the 26th of July, Dr. Gibbs says : "In 

 reply to your proposition I can only say that I will willingly join 

 you in your investigation, provided that on your return to Philadel- 

 phia you find that your engagements will prevent you from accom- 

 plishing your work alone. You ought, if possible, to have the entire 

 credit which is justly due to you. If, however, you cannot under- 

 take the matter alone, then I will add my labors to yours and we 

 will publish in our joint names." Thus began the association of 

 these two eminent men in the investigation which has since become 

 famous. In the following November Dr. Gibbs himself discovered 

 a new ammonia-cobalt base, obtained by passing nitrogen oxides 

 into solutions of the compounds described by Dr. Genth. Its salts 

 have a dark sherry-wine or brown-yellow color, and the new base 

 differs from the others in the fact that it contains nitrogen dioxide 

 as a coupler in addition to ammonia. 



In the joint monograph of Gibbs and Genth, which was published 

 by the Smithsonian Institution in 1856, and afterward printed in 

 the American Journal of Science, the nomenclature of Fremy is sub- 

 stantially adopted though somewhat modified. Instead of " Roseo- 

 cobaltiaque " and " Luteocobaltiaque," as Fremy proposed, the 

 names " Roseocobalt " and " Luteocobalt " are employed for the 

 two bases originally discovered by Dr. Genth; that of " Purpureo- 

 cobalt " being given to the base discovered by Claudet, " Xantho- 

 cobalt " to that discovered by Gibbs, and " Fuscocobalt " to the 

 one described by Fremy. The^ authors also followed Fremy' s 

 example in referring the colors of these substances to the chromatic 

 scale of Chevreul. The crystallographic determinations given in 

 the memoir were made by J. D. Dana. After describing the 

 methods of analysis used, the monograph goes on to state at length 

 the mode of preparation and the properties of the salts of roseo- 

 cobalt, purpureocobalt, luteocobalt and xanthocobalt, together with 

 the results of their analysis. It concludes with a theoretical discus- 



