in the solution of manganese. We take then 50 c. c. of the original
solution of ferrous sulphate diluted as above, and determine the total
ferrous salt.

The difference between the two determinations corresponds to the ferrous
salt which has been peroxidized by the manganese peroxide. The quantity
of iron thus peroxidized multiplied by 0.491 gives the quantity of
manganese contained in the portion operated upon. In the case of a
steel or cast iron containing but little manganese it is convenient to
dissolve the peroxide in 25 c. c. only of the ferrous solution. Small
Gay-Lussac burettes may then be used in the titration of only 0.010
meter internal diameter, and graduated into one-twentieth c. c., which
allows of great exactitude in the determination. For a spiegeleisen
not more than 1 gramme of the sample should be taken, and for a
ferro-manganese 0.3 gramme.

* * * * *




MANGANESE AND ITS USES.


Manganese is one of the heavy metals of which iron may he taken as the
representative. It is of a grayish white color, presents a metallic
brilliancy, and is capable of a high degree of polish, is so hard as to
scratch glass and steel, is non-magnetic, and is only fused at a white
heat. As it oxidizes rapidly on exposure to the atmosphere, it should be
preserved under naphtha.