C. H. Wing on certain Double Sulphates 359 
one easily obtained in a state of purity. This salt, dried over 
sulphuric acid, was weighed in a porcelain crucible, sulphuric 
acid added and the cobalt converted into anhydrous sulphate by 
eating as above. 
L = Vv. 
Substance taken 9005 «4041 «= «12340-10478 =: 10418 
oSO, obtained 5573 «= 2498 "7625 6497 6443 
Percentage €oSO , 81°90 61°81 61°80 62°01 61°89 
_ Gibbs and Genth obtained as a mean of four analyses of this 
Salt 61-90 per cent of CoS6,. 
_ Taking the atomic weight of cobalt as 59° which number is 
indicated by these analyses, we have as the percentage of cobalt 
found— 
. IL. Il. VL Ve Mean Calculated. 
2356 86-23-53 23°58) 23°80 )=— «2856 = 28556 28-56 
From the above it appears that this method for determination 
esired. 
cobalt is all that could be d ee 
determining the sulphuric acid in the substance a portion 
of 
| 4 boiling heat, i allowed to stand for twelve hours or more 
| before filterine. : ; 
_ The total amount of hydrogen was determined by combus- 
ion of the substance mixed with chromate of lead, placing in 
the anterior portion of the tube, first oxyd of copper, then me- 
e Seemed to indicate the compound formed to be a ceric salt. 
The filtrate from this tet precipitate showed powerful ate 
