Cobaltous iüto Cobaltic Nitrite* 5 



stage, therefore, of the conversion of cobaltous nitrite into the 

 crystals obtained is to be expressed by 



7Co",Co"2(NO,)io(OH),= 



2Co(N02). + 4Co';Co";(NO,)9(OH)„ + Co"hCo"'6(N02)3,(OH)i5, 



the crystalhne substance, Co"i4Co'"6(N02)3o(OH),6, being itself a 

 compound of 3 Co"3Co"'2(N02)9(OH), with 3 Co (NO,)(OH) and 

 2 Co(OHX,. 



In accordance with the remarkable constitution of the crystal- 

 line salt, indicating as it does that atoms of hydroxyl like nitroxyl 

 groups can pair together between cobaltic and cobaltous 

 atoms, is the behaviour of the salt when it is acted upon 

 by half the quantity of an alkali carbonate equivalent to its 

 cobaltous atoms. Out of 23-7 parts per cent of cobaltous cobalt 

 present in the salt, 14-1 parts were precipitated in this way. The 

 equation expressing this result is 



Co"uCo"'o(NO,)3o(OH)i6 + 7K,CO,=8KNO, + 7CoCO,+ l-5Co(OH), 



1-5 



For 1-5, theory I'equires 2, and, since partial precipitation in this 

 way can hardly lay claim to great accuracy, the cobaltous hydroxy- 

 cobaltinitrite may allowedly be written as (p. 3) 



Co"eCo",(NO,)io(OH)8. 



A potassium cobaltous salt is oljtained by adding a solution of 

 potassium carbonate, just so long as it continues to cause immediate 

 precipitation, to the solution of cobaltous nitrite after its spon- 

 taneous conversion into hydroxycobaltinitrite, filtering, and 

 gradually mixing the red-coloured filtrate with about twice its 

 volume of absolute alcohol. The potassium cobaltous salt is thus 



