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LI II . Chemical Notices from Foreign Journals. 

 ByE. Atkinson, Ph.D., F.C.S. 



[Continued from p. 313.] 

 \^"ITH a view to finding an effectual method of separating 

 ™ * from each other Mosander's three bases, yttria, erbia, and 

 terbia, Popp undertook an investigation of yttria. He has pub- 

 lished the results of his investigation separately, and has given 

 a summary of it in Liebig's Annalen*, from which the following 

 is taken. 



As distinct oxides he considers that erbia and terbia have no 

 separate existence, or rather they are not the oxides of hitherto 

 unknown metals, but are identical with the oxides of cerium and 

 didymium. Mosander's oxide of yttria contains both alkali and 

 lime. Hence erbium and terbium, which have heretofore been 

 regarded as elements, though not altogether without some doubt, 

 must now be struck from the list. 



Pure yttria is separated from its accompanying earths by 

 means of carbonate of baryta, which completely precipitates 

 oxides of cerium and didymium even in the cold, but not yttria. 

 It is necessary that the cerium be present as sesquioxide. When 

 freshly precipitated, yttria closely resembles hydrate of alumina, 

 and is of a pure white colour. A tinge of red indicates that it 

 contains oxide of cerium. Ignited, it is a heavy yellowish-white 

 powder, which, if quite white, contains alkali and lime. Hy- 

 drated oxide of yttria corresponds approximately to the formula 

 YO, 2 HO. It is a strong base, and expels ammonia from its 

 salts when boiled. In its relations to the alkalies it shows close 

 analogies with magnesia. 



All the yttria salts have a distinctly light rose-colour, which 

 is not caused by the presence of manganese or didymium, but 

 is peculiar to them, and which they lose when they are dehy- 

 drated. 



It is characteristic of the yttria salts that when a solution is 

 interposed between the prism of a spectroscope and a strongly 

 luminous gas-flame, five black lines are seen, which are quite dif- 

 ferent, both in number, position, and intensity, from the similar 

 lines of didymium. One of these lines is in the deep violet, and 

 the other in the extreme red. 



The combining proportion of yttrium was determined afresh, 

 inasmuch as Berzelius, who found the number 40, had evidently 

 worked with impure yttria. Popp used the sulphate which 

 separates from a boiling solution of sulphate of yttria, and which 

 Berzelius had employed. The yttria was precipitated by means 

 of oxalic acid, and the oxalate ignited and weighed. From the 



* August 1864. 



