EXPERlUETiTI ON ILLlNITfi. SJ 



more difBcuU solubility of mine was owing to the methoa f* 

 had employed to procure it, and to the strong heat to which 

 I had subjected it; whereas the oxide of cerium from cerite 

 had been examined in the state of carbonate. 



7. In the many experiments made upon this powder, and Some paaiie«» 

 up«Ki oxide of cerium from cerite, i repeated everything that J'^pfife^^ 

 had been established by Beizelius and Hisinger, Klaproth noticed, 

 and Vauquchii, and had an opportunity of obseiving many 

 particulars, which they have not nr.ticed. It may be worth 

 while, therefore, without repeating the details of there 

 chemists, to mention a few circumstances, which wilLvbe 

 found useful in examining this hitherto scarce oxide, i ^ 4^'* 



a. The precipitate occasioned by the oxalate of ammoiiia 

 is at first in white flocks, not unlike that of muriate of sil- 

 ver, but it soon assumes a pulverulent form. It dissolves 

 readily in nitric acid, without the assistance of heat. The ' 



same remark applies to the precipitate thrown down by the 

 tartrate of potash. But tartrate of cerium is much more 

 soluble in acids than the oxalate. 



6. The solution of cerium in acetic acid is precipitated 

 gray by infusion of nut-galls. Cerium is precipitated like- 

 wise by the same reagent from other acids, provided the so- 

 lution contains no excess of acid. This fact was first observed 

 l?y Dr. Wpllaston, who communicated it to me last sum'* 

 mer. 1 immediately repeated his experimei)ts with success. 



c. Cerium is not precipitated from its solutions in acids 

 by a plate of ziuc. In some cases, indeed, I have obtained 

 a yellowish-'ed powder, which was thrown down very slowly. 

 But it proved, on examination, to consist almost entirely 

 of red oxide of iron, and of course only appeared when the 

 ^lutioD of cerium was contaminated with iron. 



l^eof much importance. The specific gravity of the specimen was 4* 149, 

 I fvund it composed as follows : 



A white powder, left by muriatic acid, and presumed tq basilica, 47-5 



Ked oxide of cerium 44* 



Iron , .'1 i .'i', ; , , . 4« 



Volatile matter , S^ 



^^» •••••••••••' • '_^ u,'%^ 



1000 

 d. Tho 



