2 RESEARCHES ON THE 



though his memoir contained many interesting and valuable contributions to our 

 knowledge of the oxides of cobalt, it threw no light upon the true nature of the 

 ammoniacal compounds, except by establishing in them the existence of sesqui- 

 oxide of cobalt. The subject was next investigated by Beetz, 1 who analyzed an 

 ammoniacal sulphate and nitrate of sesquioxide of cobalt formed during the 

 direct oxidation of ammoniacal solutions. These analyses led to the formulas 

 Co s 3 .3SO s +3NH 8 + NH 4 0, and Co 2 3 -3NO fl +3NH 3 +NH 4 0, but as the substances 

 employed were not crystallized, and as the analytical methods were difficult to 

 execute, but little reliance could be placed in the results. Beetz, however, con- 

 sidered the sesquioxide of cobalt in these compounds as playing the part of an 

 acid, the ammonia being present as a salt of ammonium. 



The oxidation of ammoniacal solutions of various salts of cobalt was also 

 observed by Rammelsberg, 2 and the products of the action in several cases analyzed. 

 None of the formulas obtained, however, appear to belong to well defined and dis- 

 tinct compounds. 



A memoir published by one of ourselves, in 1851, 3 contained the first distinct 

 recognition of the existence of perfectly well defined and crystallized salts of am- 

 monia-cobalt bases ; in fact we have not been able to trace in any earlier paper 

 even the idea of the existence of such a class of compounds. The results made 

 public in this paper had been obtained by the author, in Marburg, in 1847, had 

 been at that time freely though verbally communicated, and a suite of the salts 

 obtained had been left in the laboratory at Giessen. Want of opportunity pre- 

 vented a complete and systematic investigation, particularly from the analytical 

 point of view. The memoir in question contained, however, besides several 

 analyses, an accurate description of the two bases now to be described under the 

 names of Boseocobalt and Luteocobalt. Though the analyses Avere from neces- 

 sity not sufficiently complete and extended to fix the constitution of the bases in 

 question, yet the fact is indisputable that this memoir contained, not merely the 

 first announcement of the existence of ammonia-cobalt bases, but also a scarcely 

 less accurate and complete description of two of these bases than any which has 

 since appeared. 



As its title states, the memoir in question was intended simply as a preliminary 

 notice ; circumstances, however, prevented a speedy resumption and continuation 

 of the subject. In a paper published in 1851, 4 Claudet described with some detail 

 the properties of the chloride of Purpureocobalt, and the mode of obtaining it, as 

 well as a few other ammonia-cobalt salts. With the exception, however, of more 

 complete analyses, the memoir in question contained nothing which is not to be 

 found in the previously published paper above alluded to. In two notices com- 

 municated to the Academy of Sciences 5 in the same year, Fremy announced as his 



1 Pogg. Ann., LXI, 494, 480, 490. 



3 Pogg. Ann., XLVIII, 208. XLIV, 268. 



5 Nordarnerikanischer Monatsbericht fur Natur. und Heilkunde, 1. Januar. 1851. VorliiuGge 

 Notiz iiber gepaarte Kobaltverbindungen von Dr. Friedrich August Genth. 



4 Phil. Mag., II, 253, and Ann. de Chimie et de Physique, XXIII, 483. 



5 Comptes Rendus, XXXII, 509, 808. 



