28 PROCEEDINGS OF THE AMERICAN ACADEMY 



acetic acid being added to prevent decomposition. The salt is easily 

 soluble in hot water, and crystallizes readily, though not in well-defined 

 crystals, from the solution. Like the neutral chromate, it is available 

 as a means of recognizing salts of xanthocobalt, and of obtaining them 

 in a state of purity. Of this salt 



0-6o70gr. gave 0-8200 gr. CrO,Ba= 53-33 per cent Cr.O.. 

 0-3974 gr. gave 0-4950 gr. CrO.Ba = 53-23 percent Cr^O^. 

 0-4868 gr. gave 0-1830 gr. CrgOj =53-40 per cent Crp^. 



The formula Co2(NH3)^Q(N02)2(Cr20^)2 requires 53-22 per cent. 



lodosulphates. — A solution of potassic iodide gives no precipitate at 

 first with one of nitrate of xanthocobalt, but, after standing some time, 

 pale brown yellow acicular crystals of the iodide Co2(NH3)^|3(N02).2l4 

 are formed. When a solution of iodine in potassic iodide is added to 

 one of nitrate of xanthocobalt, iodine is precipitated in crystals, but no 

 hyperiodide is formed, as in the case of the iodide of the octamin 

 series already described. Potassic iodide gives, with a solution of 

 sulphate of xanthocobalt, brown-yellow needles, which, after re-solution, 

 give larger prismatic crystals. Of these 



0-5396 gr. gave 02207 gr. SO^Co = 15-57 per cent cobalt. 

 0-8856 gr. gave 0-2689 gr. SO^Ba^ 12-51 per cent SO^. 

 0-4541 gr. gave 0-1288 gr. silver = 33-37 per cent iodine. 



The formula Co. .{^U.^) ^^{^0.^)^0,1., -\- 20l\ requires 



Calculated. Found. 



Cobalt, 2 15-40 15-57 



Iodine, 2 33-16 33-37 



SO^ 1 12-53 12-51 



"When a sohxtion of iodine in potassic iodide is added to one of sulphate 

 of xanthocobalt, very beautiful, deep ruby red, well-defined crystals 

 are formed, which are readily decomposed by hot water, with evolution 

 of iodine vapoi", and cannot be recrystallized for analysis. Of these 

 crystals 



0-6094 gr. gave 86-5 c.c. nitrogen at 13° C. and 758-6"'" (h = 2-08""') 



= 1663 per cent nitrogen. 

 0-2142 gr. gave 0-0687 gr. SO^Co= 12-21 per cent cobalt. 

 0-6104 gr. gave 0-1870 gr. SO^Co= 11-64 per cent cobalt. 

 0-3940 gr. gave 0-1672 gr. silver = 49-90 per cent iodine. 

 0-5437 gr. gave 0-2310 gr. silver = 49-96 per cent iodine. 

 0-3020 gr. gave 0-0724 gr. SO,Ba= 9-87 per cent SO,. 

 1-0627 gr. gave 0-2787 gr. SO^Ba = 1080 per cent SO,. 



