46 



RESEARCHES ON THE 



OXALATE OF LUTEOCOBALT. 



When a solution of oxalate of ammonia is added to one of a soluble salt of 



Luteocobalt, a buff colored precipitate of fine needles is thrown down, which is 



insoluble both in hot and cold water, but which readily dissolves in a solution of 



oxalic acid. From this solution the neutral oxalate crystallizes in beautiful 



prismatic crystals, having the color of the sulphate and chloride. In dry air the 



crystals lose water like those of the other hydrated salts of Luteocobalt. The 



oxalate has the formula 



6NH 3 .Co 2 33 3C 2 03+4HO 



as the following analyses show : 



0.4330 grs. gave 0.2040 grs. sulphate of cobalt = IT. 99 per cent, cobalt. 



0.4228 grs. gave 0.2000 grs. " ' 



0.5345 grs. gave 0.2529 grs. " ' 



2.0805 grs. gave 0.8380 grs. carbonic acid 



The formula requires 



Eqs. Calculated. 



Cobalt . . 2 17.93 



Oxalic Acid . 3 32.82 



= 18.00 " 

 = 18.01 " 

 = 32.95 per cent, oxalic acid. 



Found. 

 17.99 18.00 18.01 

 32.95 — — 



It would a priori appear probable that there exists an acid oxalate of Luteocobalt 

 corresponding to the acid carbonate, but we have not yet been able to obtain such 

 a salt. The oxalic acid in this compound cannot be easily reduced by a solution 

 of terchloride of gold, nor can it be completely separated from the base by means 

 of a solution of chloride of calcium. 



CARBONATES OF LUTEOCOBALT. 



The neutral carbonate of Luteocobalt is readily formed by decomposing a solu- 

 tion of chloride of Luteocobalt by carbonate of silver. The yellow solution, by 

 evaporation, yields sherry-wine colored crystals of the carbonate. The salt closely 

 resembles the other soluble salts of Luteocobalt; is easily soluble in hot water, and 

 crystallizes well by slow evaporation. During evaporation, however, the solution 

 absorbs carbonic acid from the air, and crystals of the acid carbonate are found 

 mixed with those of the neutral salt. According to Prof. Dana's measurement, 

 the crystals of the neutral carbonate belong to the trimetric system, and approach 

 Aragonite in form. Fig. 20 represents a crystal of this salt: 



Fig. 20. 



1:1= 116° 50' 

 I : i% = 121° 35' 

 15 : 1? (top) = 114° 16' 

 \i : K over i% = 65° 44' 



a:b:c = 1.0509 : 1 : 1.6265 



