384 On A L LA NlTE, a new 



h. The foliation of cerium in acetic acid is precipitated grey 

 by infufion of nut-galls. Cerium is precipitated likewife by 

 the fame re-agent from other acids, provided the folution con- 

 tain no excefs of acid. This fact was firft obfeVved by £)r 

 Woll aston, who communicated it to me lafl fummer. I im- 

 mediately repeated his experiments with fuccefs. 



c. Cerium is not precipitated from its folution in acids by 

 a plate of zinc. In fome cafes, indeed, I have obtained a yel- 

 lowifh-red powder, which was thrown down very ilowly. But 

 it proved, on examination, to conftft almoft entirely of red 

 oxide of iron, and of courfe only appeared when the folution of 

 cerium was contaminated with iron. 



d. The folutions of cerium in acids have an aftringent tafte, 

 with a perceptible fweetnefs, which, however, is different from 

 the fweetnefs which fome of the folutions of iron in acids pof- 

 fefs. 



e. The muriate and fulphate of cerium readily cryftallife ; 

 but I could not fucceed in obtaining cryftals of nitrate of ce- 

 rium. 



/. The beft way of obtaining pure oxide of cerium, is to 

 precipitate the folution by oxalate of ammonia, wafh the preci- 

 pitate well, and expofe it to a red heat. The powder obtained 

 by this procefs is always red 5 but it varies very much in its 

 made, and its beauty, according to circumftances. This pow- 

 der always contains carbonic acid. 



g. I consider the following as the eftential characters of ce- 

 rium. The folution has a fweet aftringent tafte : It is precipi- 

 tated white by prufliate of potafh, oxalate of ammonia, tartrate 

 of potafh, carbonate of potafh, carbonate of ammonia, fuccinate 

 of ammonia, benzoate of potafh, and hydrofulphuret of ammo- 

 nia : The precipitates are re-diflblved by nitric or muriatic 



► acids : 



