CobaUous into Cobaltic Nitrite 7 



products. Its composition agrees well with the formula, 

 Ag3Co";(NO,)6(OH)3:— silver, f. 42-12 and 41-97, c. 42-13; cobalt, 

 f. 15-61 and 15-56, c. 15-35; nitrogen, f. 10-70 and 10-66, c. 10-92. 

 The analyses were made on different preparations of the salt. 

 Sometimes, instead of the salt or with it, silver nitrite and cobaltic 

 precipitates are formed. The simplest ec|uation for expressing the 

 interaction in which the silver hydroxycobaltinitrite is alone 

 precipitated is : 



2Co"iCo";(N02)io(OH), + 6AgN03 = 



Co(OH), + 4Co(NO,X> + 3Co(N03), + 2Ag,Co";(NO,)6(OH)3, 



it being understood that the cobaltous hydroxide remains in solu- 

 tion in combination with undecomposed hydroxycobaltinitrite, and 

 that the cobaltous nitrite similarly coixibines or else proceeds to 

 pass of itself into hydroxycobaltinitrite. The constitutional for- 

 mula of the silver salt is (AgNOs N02)3Co"'2(OH)3. 



The three salts which have been obtained in this investigation 

 of the change undergone by cobaltous nitrite in aqueous solution, 

 namely, hydroxycobaltous hydroxycobaltinitrite, potassium 

 hydroxycobaltous hydroxycobaltinitrite, and silver hydroxycobalti- 

 nitrite, are not the first of the hydroxycobaltinitrifces which have 

 been prepared and examined. But the method of getting these 

 others differed from that used in the present work, in that the first 

 step was the dissolution of cobalt carbonate in presence of water by 

 the action of the nitrous gases from nitric acid and arsenious oxide. 

 By taking the nitrite or carbonate of another metal with the cobalt 

 carbonate, double salts were obtained. The salt of the other 

 metal was taken in the proportion of three equivalents to two of 

 cobalt carbonate, so that by passing in the nitrous gases long 

 enough, normal cobaltinitrites could be and were thus prepared, 



