68 



Mr David Forbes on the Chemical 



The precipitate on filter was dissolved in a little dilute 

 sulphuric acid, then greatly diluted with water, and boiled for 

 some time, when a small quantity (0*26 gr.) of a white pre- 

 cipitate fell, which was weighed and tested for titanic acid, 

 but found only to consist of columbic acid, (that is, if no 

 tantalum is present, as no means of separating them is known,) 

 it was therefore added to the former. 



The solution after this precipitation was supersaturated with 

 ammonia in excess, and then oxalic acid added until a very 

 faint acid reaction was perceptible. The oxalates thus preci- 

 pitated were filtered off, washed, ignited, and dissolved in 

 hydrochloric acid ; the solution treated with sulphate of 

 potash to separate the cerium and yttria, which were both 

 determined in the usual manner. 



The filtrate from the precipitated oxalates was now preci- 

 pitated by hydrosulphuret of ammonia, and the alumina, 

 iron, and uranium determined as in the previous analysis. 



The results obtained were as follows : — 



Mineral employed for water determination, 29*42 grs. 



Loss on ignition, . . 1*33 ,, 



Mineral employed in analysis 



Columbic acid obtained, 



Do. on boiling, 



Carbonate of lime, 



Ignited oxalates, 



Yttria, 



Sesquioxide of cerium, 



■ of iron, 



Oxide of uranium, 

 Alumina, 



From which the per centage calculated will be : — 



Oxygen, 



Columbic acid, . 44-90 % 



Alumina, . 5-66 



Lime, . 0-81 



Yttria, . 29.72 



Protoxide of cerium, 5*35 



of uranium, 3*03 



of iron, 6*26 



Water, . 4-52 



100-25 

 If we calculate the yttria and columbic acid as before, the 



2-35 



55 



5-29 



55 



0-26 



55 



0-18 



55 



4-37 



55 



3-67 



55 



0-71 



55 



0-86 



55 



0-39 



55 



0-71 



■)■> 



2-64 



0-23 



2 



0-77 



0-35 



1-38 



4-02 



