Lawrence Scientific School. 61 
According to my own observations, the sesquioxyds of iron 
and aluminum cannot be separated from sesquioxyd of chro- 
mium by boiling with acetate of sodium, although the last men- 
tioned oxyd is not precipitated when alone in solution. In this 
case it is necessary to oxydize the chromium to chromic acid by 
chlorine in the manner already pointed out. 
3. 
On the separation of manganese from cobalt, nickel and zine.— 
Schiel’s method of separating manganese from the alkaline earths 
by adding acetate of sodium to the mixed solutions, heating the 
liquid gently and then passing chlorine through it so as to con- 
vert the manganese into a hydrate of the sesquioxyd, is better 
than that formerly given by myself in which peroxyd of lead is 
used as the oxydizing agent. With respect to Schiel’s method, 
however, it must be remarked that it cannot be employed to sep- 
arate manganese from nickel or cobalt, because both of these 
metals are converted into higher oxyds under the same circum- 
stances. Nickel may, as Popp has recently shown, be completely 
precipitated as a deep blue hyperoxyd, while as I have myself 
observed, cobalt is also oxydized, though not precipitated, unless 
the solution is boiled with an alkaline carbonate. In separating 
manganese from zinc, calcium or magnesium, I have repeatedly 
found that a second treatment is necessary in order to obtain a 
perfect separation. This second treatment may be neglected in 
separating manganese from calcium and magnesium, but not in 
Separating it from zinc, although the addition of a few drops of 
exact, 
hough the method of separating manganese from other bases 
Anhydrous. arak 
_ Manganese, - - 35°10 ‘96 53 
oe a ae 35°13 35°26 
Oxygen, - . = 24°87 26°90 27°20 
Sige 4. 7 
: 10000 ©—«'100:00~—S—«*100-00 
- Neglecting the water, which may have been, in part at least, 
ically combined, and which amounts to between three 
