1835.] Chemical Analysis of Gadolinite, Sfc. 421 



4. Disulphated peroxide of Cerium. — A sulphur yellow, in- 

 soluble powder, obtained by dissolving sesquisulphated per- 

 oxide of cerium in water. When heated it becomes white, 

 and reddish by a gentle ignition. Before ignition it dis- 

 solves easily in acids, but after being heated to redness it 

 is not acted on by nitric, muriatic, or nitro-muriatic acids. 



2*18 grs. of the yellow salt were dissolved in a flask with 

 muriatic acid. Carbonate of ammonia was then added, and 

 the mixture boiled. The precipitated carbonate collected 

 and well washed, left, after ignition, 1*28 grs. of peroxide 

 of cerium. 



The residual solution mixed with nitric acid gave 1*305 

 grs. of sulphate of barytes = 0*45 sulphuric acid. This 

 analysis gives us, 



Peroxide of cerium . . . 1*28 or 14-4 

 Sulphuric acid . . . . . . 0*45 ,, 5* 



Water 0*45 



2-18 

 As nearly 2 atoms of oxide as could be expected from an 

 analysis on so small a scale. 



5. Potash-sulphate of Cerium. — A granular white powder, 

 scarcely soluble in water, but easily so when a little acid 

 is added. 



18*9 grs. of the salt, previously gently ignited, were 

 dissolved in a flask in dilute muriatic acid. Carbonate of 

 ammonia was then added ; the mixture was boiled, and 

 filtered while boiling hot. The carbonate of cerium, after 

 being well washed, weighed 9*5 grs. reduced by a strong 

 ignition to 6*00 grs. peroxide = 5*57 grs. protoxide. 



From the residual solution, mixed previously with nitric 

 acid, the sulphuric acid was thrown down by barytes. The 

 ignited sulphate weighed 23*467 grs. = 8*23 grs. sulphuric 

 acid. 



The residual solution, the excess of barytes having been 

 removed by sulphuric acid, was evaporated to dryness and 

 ignited, mixed with carbonate of ammonia and again 

 ignited. The sulphate of potash remaining, weighed 9*53 

 grs. — 5*20 grs. of potash. This analysis gives, 



Protoxide of cerium . . 5*57 or 6' 5 - 1 atom. 



Potash 5*20 „ 6*06 - 1 atom. 



Sulphuric acid .... 8*23 „ 9*6 - 2 atoms. 



