to some extent with additions in the range of about 0 016 to 0 50 cerium in mischmetal with generally higher recoveries occurring at higher additions as illustrated in fig1 similar results for calcium recovery show a relatively constant 20 or less in the addition range of 0 02 to 0 29 calcium as nickel calcium this is shown in fig2 the cerium and calcium contents in the four groups of heats in fig1 can be summarized as follows ______________________________________heat ce ca______________________________________rv 6211 6216 003 to 027 001 to 009 rv 6246 6251 003 to 41 005 to 052 rv 6297 6301 002 to 095 005 to 045 rv 6417 se23 043 to 093 005 to 011 ______________________________________ as will be seen most heats in the first group had poor workability the cerium and calcium additions generally being too low the same is true of the second group rv 6246 6251 but for another reason the cerium annd calcium additions were generally too high best results were obtained with the heats in the last two groups many of which have cerium and calcium contents falling within the critical limits of the invention in the initial series of heats shown in table i rv 6211.