C. Wolf on the equivalent of Cerium. 61 
These results give for the anhydrous sulphate: 
By Ba Bs Mean. 
Cerous oxyd, -..-32<6 57°349 57°335 57°329 57°338 
Sulphuric acid, -_-.----- 42°651 42°665 42°671 42°662 
100°000 = 100°000 100°000 100°000 
Equivalent, 45°184 -45°754 45°741 45°760 
The hydrous sulphate has the composition: 
By Bs Bs Mean. 
Perous oxyd, aa: - 28 46°409 46°767 46°544 46°573 
Sulphuric acid, 34515 34°802 34642 3.4653 
Water, .  19°076 18°431 18°814 18°774 
100:000 100°000 100°000 100°000 
From these analyses it becomes evident that the composition 
of this hydrous sulphate differs from that previously described 
and that it can be expressed by the formula 2(CeO, SO,)+ 
SHO, which would give: 
Cerous oxyd,-.------+------------------ 46°241 
Sulphuric acid, -.-.--------------------- 34°406, 
ater, 
The equivalents resulting from these analyses differ very much 
equivalents 46-058 and 46-072 were certainly made with cerium 
salts free or almost free from didymium. The salt ¥ ch 
of the equivalent of cerium from 46° to 45°760 is not owing to 
the separation of didymium, but to that of another foreign 
substance, 
The mother-liquor and wash-waters from Né gave with am- 
monia a very minute precipitate. 
Encouraged by the results obtained by this method of sepa- 
ration, I have continued in the same manner. A portion of 
N@ was dissolved in nitric acid, and this solution fo peor oe 
__ ted by boiling water. The new precipitate Ny was almost white. 
“Inthe mother-liquor the presence of didymium could hardly 
be detected by the line D, while in the precipitate itself not a 
trace was visible. ee : 
___ The sulphate prepared from Ny again showed the habitusof 
‘the first sulphates and crystallized in slender crystals, w. ich 
gave the same angles with no new modifications ; analysis — 
proved that their composition also was nearly the same. 
