AMMONIA-COBALT BASES. 3 



own, the discovery of a class of compounds containing cobalt and ammonia, and 

 produced by the oxidation of am'moniacal solutions of protosalts of cobalt. In the 

 following year his complete memoir appeared. 1 In this Fremy describes anew the 

 ammonia-salts of protoxide of cobalt, first obtained by H. Rose, passes then to the 

 description of two new classes of compounds discovered by himself, and named by 

 him Oxy-cobaltiaque and Fusco-cobaltiaque, and finally describes at some length 

 the principal salts of Genth's two bases, the constitution of which he correctly 

 determines. Fr£my appears not to have been aware that these two bases had 

 been described in a manner little less complete than his own two years before the 

 appearance of his memoir. The chloride of Luteocobalt and its platinum salt 

 have also been described and analyzed by Rogojski, 2 and what we now term the 

 chloride of Purpureocobalt, by Gregory, 3 who corrected the analyses of Fr^my. 



The researches of Claus 4 on the ammonia-iridium and ammonia-rhodium bases 

 established the existence of compounds of these metals exactly analogous to Roseo- 

 cobalt and its salts, and chemists will look with impatience for the publication of 

 his results in detail. Recently Weltzien has published some theoretical views on 

 the constitution of the ammonia-cobalt bases which possess much interest. 



The salts of Xanthocobalt were discovered in November, 1852, by W. G., and 

 the principal results which are contained in the present memoir were communi- 

 cated to the American Association for the Advancement of Science, at its meeting 

 in Cleveland in August, 1853. The formulas of several of the more remarkable 

 bases are also given in a Report on the recent progress of organic chemistiy, read 

 before the same association, at its Providence meeting in August, 1855. The 

 nomenclature of tli,e ammonia-cobalt bases proposed by Fremy is so simple and 

 convenient that we have adopted and extended it to meet every case. We have, 

 however, considered it desirable to drop the terminal syllable "iaque," employed 

 by Fr^my, not merely because it is not; an English termination, but because by 

 omitting it we obtain shorter and more convenient words. Thus, we say Roseo- 

 cobalt and Luteocobalt, instead of Roseo-cobaltiaque and Luteo-cobaltiaque, or 

 Roseo-cobaltia and Luteo-cobaltia, which are the English equivalents. The 

 shorter names, as will hereafter appear, also agree better with our own theoretical 

 views, since we consider the compounds in question conjugate metals and not 

 ammonias. 



With the view of making the description of our salts as complete as possible, we 

 have followed the excellent example of Fremjr, and referred the colors of these 

 substances to Chevreul's chromatic scale. Fremy had the advantage of Chevreul's 

 own determinations. We have employed, for the purpose^ the chromatic scales 

 recently published in Paris by Digeon, and which appear to be reliable ; in any 

 event they give some precision to determinations of color. As we have found that 

 very many of the salts of the ammonia-cobalt bases exhibit a well marked dichro- 



1 Ann. de Chimie et de Physique, XXXV, 257. 

 3 Journal fur praktische Chemie. 

 3 Ann. der Chemie und Pharmacie, LXXXVII, 125. 



* Bulletin de l'Academie de St. Petersburg, 1855, XIII, 97, quoted iu Handworterbuch der reinen 

 und angewandten Chemie, VI, 843. 



