JULY 19, 1923 FERGUSON: OXIDES OF IRON 275 
251.03 251.19 
4326.98 (2III) 4334.86 (3I1II) 4346.60 (3IV) 
23104 .34 41.98 23062.36 62.53  23000.03 
405.49 405.48 
4404.28 (S5III) 4412.44 (III) 
22698 .85 41.97 22656.88 
The lines which have thus far been classified are about 100 in num- 
ber, or very nearly 10 per cent of the total recorded for the arc spectrum. 
Work is still in progress and it is hoped to present more complete details 
of the investigation in the Scientific Papers of the Bureau of Standards. 
The element zirconium, of atomic number 40, follows titanium in 
column IV of the periodic classification. We have found in its spec- 
trum multiplets similar to some of those recorded below. We expect 
also to present the details of this investigation in the near future. 
CHEMISTRY.—The oxides of tron... JoHN B. FeRGuson, University 
of Toronto. 
In spite of the large amount of work that has been done upon the 
problem of the oxides of iron, our knowledge of this subject is far from 
complete. In particular, diverse views are held as to the nature of the 
iron phase, the nature of the ferrous iron phase, and the proper values of 
the equilibrium constants in the system—(H:2,H,0, Fe, FeO).2 The 
present paper deals with these points. 
I. THE IRON PHASE 
Mixtures of hydrogen gas and water vapour at atmospheric pressure 
were passed over iron at high temperatures and the resultant degree of 
oxidation noted. 
The charge was placed in a porcelain boat in an electrically heated 
tube furnace and the furnace swept out with oxygen-free nitrogen. 
The furnace was then brought up to temperature and the gas mixture 
admittted. At the end of the experiment, the gas mixture was swept 
out with the nitrogen and the charge allowed to cool. When it was 
cold it was removed and analyzed. 
1 Received May 23, 1923. The experimental work on which this paper is based was 
in part carried out by Messrs. Findlay, Robertson, Noble, Hoover and Mulligan. See 
Transactions of the Royal Society of Canada, 15: 55. 1921; 16: 273. 1922; and the volume for 
the current year. 
2 Fe and FeO are here used to designate the phases and are not meant to indicate the 
exact compositions of these phases. 
