240 



Sir W. Crookes. 



method has proceeded for a considerable time, the fractions rich in 

 victorium are collected together and submitted to another mode of 

 treatment. 



These fractions are converted into nitrates, and a small quantity is 

 thrown out by partial decomposition by heat, according to the method 

 already described. The filtrate is evaporated to dryness and again 

 fused so as to throw out a little more. This operation is repeated as 

 long as any soluble nitrate is left. Generally from six to twelve por- 

 tions are thus obtained. These form a regular series, differing accord- 

 ing to the stability of the nitrate under heat. On testing, the 

 victorium is found to concentrate in the centre portions, being less 

 easily decomposed than the earths of the cerium group and more 

 easily decomposed than those of the yttrium group. 



The fractions rich in victorium are converted into sulphates and 

 mixed with a hot saturated solution of potassium sulphate. The pre- 

 cipitate is dissolved in boiling water and mixed with a further quantity 

 of solution of potassium sulphate. This produces a small quantity of 

 a precipitate. The filtrate from the first precipitate is also mixed with 

 fresh potassium sulphate, and the operations are repeated, mixing the 

 centre solutions to one lot and the side solutions to another, as shown 

 by the lines on the diagram. It is found on photo-spectroscopic ex- 

 amination that the earths thrown out on each side are poorest in 

 victorium, whilst those in the middle are richest. After a time no 

 further concentration is effected in this manner, all the earths that can 

 be removed as being more or less soluble in potassium sulphate having 

 been eliminated. 



In thus describing the method of fractionation, my object has been 

 not so much to give a description of the plan actually carried out in 

 the laboratory — for the details have varied with each operation — but 

 to give an intelligible idea of the general manner in which a very com- 

 plicated operation is effected. *In the diagram I am supposing that one 

 particular substance, victorium, is to be separated, and I have endea- 

 voured to show its migrations and gradual concenoration as the work ^ 

 progresses, by tinting the fractions where it mostly would concentrate ; 

 the depth of tint representing the amount of concentration. 



In the purest condition yet obtained victoria is an earth of a pale 

 brown colour, easily soluble in acids. It is less basic than yttria and 

 more basic than most of the earths of the terbia group. In chemical 

 characters it differs in many respects from yttria. From a hot nitric 

 acid solution, victorium oxalate precipitates before yttrium oxalate and 

 after terbium oxalate. On fractional precipitation with potassium 

 sulphate the double sulphate of victorium and potassium is seen to be 

 less soluble than the corresponding yttrium salt, and more soluble 

 than the double sulphates of potassium and the terbium and cerium 

 groups. Victorium nitrate is a little more easily decomposed by heat 



