The glass in these lenses contains three elements (neodymium, erbium, and praseodymium) which enhance color perception while improving both contrast and depth perception.
The salts of praseodymium are green in colour, and give a characteristic spark spectrum.
The atomic weight of praseodymium is 140.5.
Meyer thinks that the susceptibilities of the metals praseodymium, neodymium, ytterbium, samarium, gadolinium, and erbium, when obtained in a pure form, will be found to equal or even exceed those of the well-known ferromagnetic metals.
Chemie, 1885, 6, 477) into two components (known respectively as neodymium and praseodymium) by repeated fractional crystallization of the double nitrate of ammonium and didymium in nitric acid.