2 PROCEEDINGS OF THE AMERICAN ACADEMY 



0-5480 gr. gave lGl-75 c.c. nitrogen (moist) at lO^'-S C and ToS^""- 



(h = 118-8'~") = 29-829^. 

 Of)!?! gr. gave 0-20.JO gr. water = G-SG^^ hydrogen, 

 0-4ot)0 gr. gave 0-2G99 gr. water = G-54% hydrogen. 



Calculatcil. Found. 



Col)alt, 2 17-87 17-08 17-18 17-16 



Nitrogen, 14 29-G9 29-82 



Hydrogen, 42 6-3G 6-3G G-54 



Oxygen, 19 46-06 — — 



The analyses are those made with the salt originally prepared by 

 Genth and myself, as I have not succeeded in obtaining it a second 

 time. The deficiency in the cobalt is perhaps to be attributed to the 

 small quantity of salt at my disposal for analysis. Admitting the cor- 

 rectness of the formula, the scaly nitrate belongs to the basic series of 

 purpureo-salts, of which the chromate already described, Co2(NH3),o.O. 

 (CrOJ.j, furnishes an example. Its structural formula will then be, as 

 compared with that of the normal nitrate : — 



r NH3— NO3 



NH3— NO3 

 NH„— NH,— NO3 

 NH.,— NH3— NO3 

 NH3— NH'„— XO3 

 NH3— NH3— NO3 

 NH,— NO, 



NH3— NH,— NO3 



I NH.,— NM3— NO3 

 t NH -NO3 



The formation of the basic nitrate may be expressed by the equation : — 



Co,(NIl3),o(N03),4-2NH,+OH, = Co,(NH3VO.(N03),+ 



2NIi,.N03. 



The readiness with which it is decomposed by water renders it impossi- 

 ble to determine the reactions of the salt ; but, as I find that chloride of 

 purpureocohalt is formed with evolution of chlorine when it is boiled with 

 chlorliydric acid, we have at least some positive evidence in favor of 

 the view which I have taken. The marked effervescence which oc- 

 curs on boiling the nitrate with chlorhydric acid is precisely similar in 

 character to that which takes place wlu-n ammonic, nitrate is heated 

 with the same acid. The normal nitrate of purpureocohalt furnishes 

 by far the most convenient method of i)assing from the pur|nireo-serie3 

 to the ro-eo-series. It is only necessary to dissolve the salt in a solu- 

 tion of ammonia, and then to allow this solution to flow slowly into 

 moderately strong nitric acid, surrounded with ice or snow so as to 

 prevent any sensible rise of temperature. The nitrate of roseocobalt 

 separates immediately as a red crystalline precipitate, nearly insoluble 



