1835. Chemical Analysis of Gadolinite, Sfc. 405 



tained suggested the following method of analyzing 

 gadolinite : — 



A. 25 grs. of the mineral, finely pounded, were boiled in 

 a flask with aqua regia, till the whole was decomposed. 

 The gelatinous silica remaining, collected on a filter, and 

 well washed, weighed, after ignition, 6*22 grs. 



B. The residual liquid was evaporated to dryness, and 

 the solid matter remaining, digested for some time in 

 distilled water. A solution of oxalic acid was then added, 

 as long as it occasioned a precipitate, and until this precipi- 

 tate was of a perfectly white colour. The oxalic acid re- 

 tained in solution the iron, glucina, &c, and threw down 

 the yttria and cerium in the state of oxalates. The whole 

 was thrown upon a filter, and the white insoluble matter 

 was well washed. When dry it was a beautiful light, 

 snow-white powder, and weighed, after ignition, 12*617 

 grs. It had now assumed a light yellow colour, and was a 

 mixture of oxide of cerium and yttria. 



Various methods of separating these two substances from 

 each other were tried, but without success, on account of 

 the perfect correspondence of the two in all their properties, 

 We were, therefore, obliged to have recourse to the common 

 method of putting a quantity of solid sulphate of potash 

 into a neutral solution of the yttria and oxide of cerium, 

 which threw down the cerium and left the yttria. But as 

 the quantities were never absolutely the same in two suc- 

 cessive experiments, this method is certainly suspicious. 

 By this method the 12*176 grs. were resolved into 



Yttria 11*087 



Peroxide of cerium . * 1-530= 143 protoxide. 



12*617 



C. The oxalic solution from (B.) was evaporated to dry- 

 ness, and ignited to destroy the oxalic acid. The residue 

 was dissolved in muriatic acid, by the assistance of heat, 

 with the exception of a few blackish grains. These were 

 at first supposed to be charcoal from the oxalic acid, but 

 after being collected and ignited they proved to be plati- 

 num, weighing 0*45 grs. 



D. The muriatic acid solution was now evaporated to 

 dryness, and to insure perfect neutralization, heated, so 

 that a small portion of the iron became insoluble on its 



