Chemistry and Physics. 413 
Expailly, Ural, East Indian, and Ceylon zircons is also easily soluble in 
oxalic acid, and that ammonia precipitates from the solution the hydrate 
of zirconia. The oxalate dried at 100°, bas the formula Zr2O0s,2C2 
into several earths, by the method of partial precipitations employed by 
Svanberg; the precipitates also contained the same amount of fixed 
base, and hence the equivalents of the different earths, if we admit the 
existence of more than one, must be the same.—Journal fur praktische 
Chemie, 57, 145. 
5. On Didymium.—Manienac has communicated a memoir on didy~ 
mium, and its principal combinations. The author effects the separation 
of didymium from lanthanum by the method of Mosander, that is to say, 
by the crystallization of the sulphates. It was found however, that the 
process could be facilitated by first dissolving the oxyds ina large ex- 
cess of nitric acid, and then successively adding small quantities of ox- 
alic acid. The first precipitates are more deeply rose-colored, and 
a known weight of the sulphate, gave as a mean of five det 
698-2 for the equivalent of the oxyd ; the analysis of the chlorid gave the 
ing the chlorid with potassium. A greyish powder was obtained, which 
in cold water disengaged bubbles of hydrogen; the particles of metal 
burned with vivid sparks when projected into a a lamp. 
pels ammonia from its salts when boiled with them ; but water slowly 
converts it intoa hydrate. The hydrate as obtained by precipitation ~ 
with potash, has a very pale rose color, and resembles alumina: the 
