88 W, Gihhs and F. A. Genth 



bases into salts of Xantliocobalt by the simple absorption of 

 NO 2 is tlius easily explained, as is tlie decomposition of the 

 salts of Xanthocobalt into NO2 and salts of Purpureocobalt. 



It is, however, proper to remark that, inasmnch as the salts of 

 Xanthocobalt which we have examined in all cases appear to 

 contain water in the proportion of at least one equivalent, it is 

 possible that the view we have taken of their constitution may 

 not be precisely accurate, and that they may contain XO3 as a 

 couplet in place of NO2. This will be evident from a simple 

 inspection of the formulae of the chlorid, nitrate, and sulphate 

 of Xanthocobalt, which are, as Ave "write them at jDresent 



NO2.5NH3.C02O, CI2+HO. 

 NO. .5NH3.C02O3, 2XO3+IIO. 

 . N02,5NH3,Co203, 2SO3+IIO. 



< No chemical analyses could, probably, in substances of such 

 high equivalents, enable us to say with certainty that there may 

 not be in these formulae an equivalent of hydrogen too much. 

 In this case the three formulas vrould read 



NO3.5NH3.C02O, CI2. 

 NO3.5NH3.C02O3, 2NO5. 

 NO3.5NH3.C02O3, 2SO3. 



^ The difficulty of analyzing these salts must also be fairly con- 

 sidered in forming an opinion as to their constitution. We 

 adopt provisionally the formula first given, in the hope that a 

 more extended study of the products of decomposition will ena- 

 ble us hereafter to fix the constitution with certainty. In the 

 mean time, we will only remark, that the analyses of tlae nitrate 

 of Xanthocobalt, which is of all salts of the base the easiest to 

 prepare in a state of absolute purity, correspond exactly to the 

 formula 



NO2.5NH3.C0.O3, 2NO5+HO, 



CHLORID OF XAXTHOCOBALT. 



Tlie chlorid of Xanthocobalt can be most readily prepared by 

 decomposing a solution of the sulphate by chlorid of barium. 

 After separation of the sulphate of baryta by filtration, a few 

 drops of acetic acid maybe added to the filtrate, which, after 

 evaporation by a gentle heat, will yield on standing large crys- 

 tals of the chlorid. This process is in fact the only one by 

 wliicli we have been able as yet to prepare this salt. 



The chlorid of Xanthocobalt cannot be prepared by the direct 

 action of a current of NOx upon an ammoniacal solution of tlie 

 chlorid of cobalt. It is true that in this case an abundance of a 

 brown-yellow crv^stalline salt is obtained, which might easily be 

 mistaken for the chlorid. The salt is, however, a mixture of a 

 large quantity of the nitrate of Xanthocobalt with a much 



