40 



PROCEEDINGS OF THE AMERICAN ACADEMY 



1-4510 gr. gave 59-5 c.c. oxygen at 22* C. and 758 """ = 5-25% 

 oxygen. 



This would correspond to one atom of oxygen for the formula given 

 above. Fremy also determined the amount of oxygen given off by the 

 action of dilute sulphuric acid, and obtained as a mean of two analyses 

 5-20^^. So far as can be judged from the analyses above, the formula 

 ■which I have given deserves the preference. On the other hand, 

 Fremy 's formula, which I double for the sake of comparison, 



Co,(NH3),A(NO,),+20H„ 



is perhaps somewhat simpler, and explains all the known reactions at 

 least equally well. The corresponding structural formulas may be 

 written, — 



Co„ 



NH,— NH3— NO3 

 NH3— N H3— NH3— NO3 



Co„ 



NH,— NH3— NO3 



NH,— :nh,— NO, 



NH3— NH3— NO3 

 NH3— NH3-NH3-N ), 

 O., 

 NH,— NH. 



-NH„— NO, 



NH,— NH— NO, 



I adopt provisionally the formula which agrees best with the analy- 

 ses, fully recognizing the j^ossibility that the other may prove correct. 

 In this connection I may mention that when iodine is added to a solu- 

 tion containing cobaltic nitrate, ammonic nitrate, and ammonia, an 

 olive-green crystalline precipitate is thrown down which contains 

 iodine, and which may prove to be either the iodide corresponding to 

 the nitrate above discussed, or an iodo-nitrate corresponding to the 

 oxy-nitrate. The formation of this nitrate may be expressed by the 

 equation, — 



4Co(N03)2+24NH34-20H.,+80 = 2.^Co.,(NH.3)j,.0,.(N03) J 



+20(NH,),. 



It is remarkable that the action of iodine upon an ammoniacal solu- 

 tion of cobaltic nitrate is not analogous to its action upon an ammoni- 

 acal solution of the sulphate. When the nitrate is heated with chlor- 

 hydric acid, a small quantity of chloride of purpureocobalt is, as I 

 find, alwaj's formed. We may have the reaction expressed by the 

 equation : — 



Co,(NH3),„0,(N03),+12HCl = Co,(NH3),,Cl,+4N03H+. 



40H,+6C1 ; 



but the greater part of the nitrate is decomposed. The formation of 

 the chloride of purpureocobalt under the circumstances is, I think, a 



