C. Wolf on the equivalent of Cervum. 59 
To facilitate comparison I will tabulate the different results: 
O=100 He=1 
Beringer, .------------------ 576°73 46°138 
ermann, .... +. -+--+2 +--+ 575°00 467000 
Marignae, .----------------- 575°00 46°000 
BSED, S wind Se ewe she Se ess 575°73 46°058 
Rammelaberg, fa eeaed eae « 575°90 46°072 
ia eteweeak eee ae 577°33 46°187 
The new number differs from all the others and is even higher 
than that obtained by Beringer with far less purified material ; 
all his salts were rose-colored, owing to the presence of didy- 
mium, my salts, on the contrary, were perfectly colorless, each 
had been re-crystallized at least ten times (always rejecting the 
mother-liquor). 
Having used the very greatest care both in the preparation 
and in the analyses of the salt, it is difficult to account for 
this high result ; either the same analytical error has been 
committed in the three pe ge or peas may be present 
while the spend I shall discuss presently. 
A sample of salt, which had been re e-crystallized twenty 
times, still distinctly showed the line D of the absorption spec- 
trum of didymium, and it being evident that by crystallization 
alone no absolutely sage seins sulphate can be Lo 
was therefore necessary to rch for ee me 
preparation. To ascertain ain the aay of the resulting product 
the cerous oxalate was ied, and from the color of the oxyd 
— by its ignition the ‘state of purity was readily ascer- 
“Mosander had already correctly stated that the brown color 
of the mixed oxyds was due to the presence of foreign substan- 
ces 5 3 he obtained the ceroso-ceric oxyd of a reddish white color ; 
a had it of an isabel color. By a slight alteration in 
e of preparation, Bunsen obtained it of a yellowish 
ich I have ‘ried, ‘but. jae > have na encouraging alts. ee 
: "The first was as follows: A small portion of the precipitate | 
Was dissolved by heating it with a few drops of sulphuric acid 
and ne solution n peste by pouring it into a large quane 
_ tity of After its conversion into oxalate © oe 
ee. precipitate ga sires a paler ceroso-ceric oe ; meee A 
| white color On Bay eae e made aie gedaan S ee 
