412 OBSERVATIONS IN CHEMISTRY AND MINERALOGY. 



liquor begins to throw out luteo salt in small octahedrons even before the 

 plete clearing. Good results were obtained when 5 grams of Co (Ni0 3 ) 2 .6H 2 and 



com- 



5 grams of NH 4 C1 were dissolved in 60 cubic centimeters of water 



Thereup 



on 



mixed with 40 c.c. of concentrated ammonia water and 1.2 grams of ammonium 

 persulfate stirred into the liquid, the resulting crystals were of the block-twin type 

 because they formed rapidly. Mother liquor was displaced twice with 5 c.c. of 

 water each time. When the third water was poured upon the crystals discolor- 

 ation started in the top layer — a 



;r — a breaking up into the luteo form and into hy- 

 droxyd. The mother liquor standing over night in a cold room deposited con- 

 siderable of the luteo salt. 1.484 grams of air-dry green crystals were obtained 

 and 0.25 grams of the orange salt. Microscopic examination shows the green 

 crystals to be contaminated with orange crystals. 

 Two analyses with 0.2 gr. each of substance gave: 



Co 



NH 3 

 N0 3 

 Cl 



S0 4 



H,0 



21.25 



26.86 



0.99 



5.60 



27.81 



17.49 (difference) 



(2 X 58.6) = 0.1813 atoms 



17 



62 



35.5 



96 



18 



1.5800 



0.016 



0.1575 



0.2897 



0.9717 



100.00 



Considering that the displacement of the mother liquor could not have been 

 thorough (compare with above) we may assume all of 0.99 per cent. NO 3 to be 

 part of extraneous NH4.NO3 and a part of the chlorine, corresponding to this, 

 must be NH 4 C1. Deducting this extramolecular NH 3 from 1.58 atoms we have 



1.548 atoms of intramolecular NH 3 left, hence Co 



2 



NH 



3 



1:8.5 



Also 



we get, assuming Cl 2 = S0 4 , Co 



(SO 



4> 



Cl 2 ) 



0.1813 : 0.3604, which is very 



close to 1 : 2. and thus follows for the analyzed material the formula 



(Co 2 (NH 3 )8.6)(S0 4 , C1 2 ) 2 .7H 2 0. 



The orange-colored crystals, though slightly soluble in 



water with yellow 



Hence they were freed from the mother 



color are not decomposed by water. 



liquor more completely, as the analysis clearly shows. 



substance was found to be homogeneous. The analysis with 0.1883 gram gives. 



Microscopically the 



Co 



NH 3 



SO* 



Cl 



NO s 



H,0 



21.88 



30.70 



33.02 



0.52 



trace 

 13.88 (difference) = 0.77 



100.00 



0.1867 atoms 



1.806 

 0.344 

 0.014 



a 



<< 



it 



u 



Hence Co 



2 



NH 



3 



Co* : SO 



4 



1 : 10 very nearly. 

 1 : 2 not quite as nearly. 



