254 Gooch and Reynolds—Reduction of the 
The Widmanstitten figures are developed very easily and 
clearly, as is usual with irons containing the percentage of 
nickel which this has, showing it to belong to the usual type of 
octahedral irons, with rather broad bands of kamacite some- 
what like those in the Cooperstown meteorite. 
I am indebted also to the courtesy of Prof. Olante, for the 
following analysis of this iron by Mr. H. N. Stokes of the 
U. S. Geological Survey : 
Re! 2-2 eee 90°51 
Na. /) ee 8°40 
Coli US: OE OE es 0°60 
Cu |.) Sea eies 0:05 
StL. Soe eee ae tr. 
Pie. 22 dea eee 0°24 
he EES oe Dieta a ee tr 
99°80 
Art, XX VIII.—The Reduction of the, Acids of Selenium by 
Hydriodic Acid ; by F. A. Goocu and W. G. REYNOLDs. 
[Contributions from the Kent Chemical Laboratory of Yale College.—XLIII.] 
A METHOD for the iodometric determination of selenious acid 
has been recently announced by Muthmann and Schaefer* 
which is based upon the reduction of selenious acid by hydri- 
odic acid and the direct titration of the iodine thus liberated. 
To determine the selenious acid it is only necessary to add it 
in solution to an acidulated solution of potassium iodide, when 
iodine and selenium are both set free in elementary form, the 
former being directly determinable by titration with sodium 
thiosulphate after addition of starch. The difficulty in the 
process is said to be the uncertainty as to the exact point in the 
titration at which the starch blue disappears from the liquid in 
which the finely divided and opalescent selenium is held in 
suspension. or this reason the process is recommended for 
use only when great accuracy is not essential. 
Evidently if the reaction between the acidulated iodide and 
selenious acid is single and complete, the process should be 
capable of improvement by removing the selenium before the 
titration is attempted. This we have succeeded in doing with-. 
out difficulty. We find the most convenient and rapid way to 
remove the finely divided selenium is to filter the liquid con- 
* Berichte d. d. chem. Gesell., xxvi, 1008. 
