4 rROCEEniNGS OF THE AMERICAN ACADEMY 



T'lnujftate. — Wlicn cliloride of purpureocobalt is boiled with sodic 

 tungstiite, WO^Xii.,, it is quickly converted into a violet granular 

 crystalliue mass, wiiicli, after wasiiing with cold water, is perfectly free 

 from chlorine. When dried in vacuo over sulphuric acid, the crystals 

 liavc a line deep violet color. The salt is but slightly soluble in either 

 cold or l)()iling water, even in presence of free nitric acid. It dissolves 

 readily iu a solution of sodic or ammonic carbonate; the solutions have 

 a fine violet color. Of this salt, 



1-0294 gr. gave 0-r>418 gr. WO3 (by mercurous nitrate) = 56-26% 



WO,. 

 2-3912 gr. gave 1-7163 gr. WO, Co (by careful ignition) = 75-9 6 <%. 



The formula Co2(NH3)j„.0.(W04)2 requires 55-11% WO, and 76-75% 

 WO,Co. 



The salt cannot be recrystallized, and was therefore probably not 

 absolutely pure. 



Oxalo-chloride. — When a solution of ammonic oxalate is added to 

 one of chloride of purpureocobalt, violet needles are soon deposited, 

 which Genth and I considered as the normal oxalate of this series, and 

 to which we gave the formula, as we should now write it : — 



Co,(NIl3),„.0.(C,0,),+30H2. 



Two determinations of cobalt and one of oxalic acid agreed very 

 closeh' with this formula. Krok * subsequently discovered that this salt 

 contains chlorine, and he assigns to it the formula : — 



Co,(Na),„a(CA)r 



On carefully re-examining this salt, I find that the percentage of 

 chlorine varies considerably in different preparations. Thus : — 



J 0-7108 gr. gave 0-2512 gr. silver =11-61% chlorine. 

 ( 0-3627 gr. gave 0-2186 gr. SO, Co = 22-95% cobalt. 



0-5093 gr. gave 0-2930 gr. SO,Co = 21-9n% cobalt. 



0-5768 gr. gave 0-2241 gr. silver 1= 12-78% chlorine. 



It is therefore probable that the chloro-oxalate contains as an admix- 

 ture a greater or less percentage of another oxalate, possibly Co^(NII.3),„. 

 0.(CJ)J^. I did not succeed in obtaining this salt from nitrate of 

 purpur('ocol)alt and ammonic oxalate, the reaction resulting only in 



{' 



• Acta Univ. Lund. 1810. I hclievo tliat this is the only error whicli has 

 been detected in the first part of tliis paper. 



