2 PROCEEDINGS OF THE AMERICAN ACADEMY 



0-5480 gr. gave 161-75 c.c. nitrogen (moist) at IC^-S C and 755-4""" 



(Ii = 118-8"^) = 29-82%. 

 0-5171 gr. gave 0-2955 gr. waters 6-36% hydrogen. 

 0-4590 gr. gave 0-2G99 gr. water = C-54f;^ hydrogen. 



Calculated. Found. 



Cobalt, 2 17-87 17-08 17-18 17-16 



Nitrogen, 14 29-69 29-82 



Hydrogen, 42 636 6-36 6-54 



Oxygen, 19 46-06 — — 



The analyses are those made with tlie salt originally prepared by 

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

 time. Tlie deficiency in the cobalt is pei'haps 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 chruraate already described, Coo(NH3),q.O. 

 (CrO^).,, furnishes an example. Its structural formula will then be, as 

 compared with that of the normal nitrate : — 



Co, 



f NH,— NO, 

 NRJ— NH,— NO 

 NH„— NIL 

 NH.;— Nil' 



Nil,— NO. 

 NH.,— NH,— NO, 



^ P, n NH.,— NH,— NO, 



>o c«2 ^ nh;-nh!-no3 



NH,— Nil,— NO3 NH,— NH.,— NO3 



N H,— NO,, [ N H,— NO3 



The formation of the basic nitra'e may be expressed by the equation : — 



Co,(NH3),„(N03)„+2NH,+OH, = Co,(NH3),„.0.(N03),+ 

 2NH,.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 chloi'ide of 

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

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

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

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

 chanicter to tliat which takes ])lace when ainmonic nitrate is heated 

 with the same acid. Tlie normal nitrate of iuir|)urc()coI)alt i'uriiishes 

 by far the most convenient method of passing from the pur|)ureo-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 slowl}' into 

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

 prt-vent any sensible rise of temperature. The nitrate of roseocobalt 

 separates iininrdiately as a red crystalline precipitate, nearly insoluble 



