6 
Transactions Texas Academy of Science. — 1908-1909. 
gen of which oxidizes the free hydrogen, or, as it is commonly called, 
depolarizes the positive pole. The subsequent oxidation of the fer- 
rous compound in solution to the insoluble ferric oxide, and its mi- 
gration toward the positive pole, which produces the “pitted” ap- 
pearance of the surface — these are unessential, secondary phenomena. 
A little consideration shows that rusting would be prevented if 
no moisture were allowed to touch the surface. This is much more 
difficult to accomplish than it might appear to be, because oils and 
paint films even, are permeated by moisture. The next possibility 
for the prevention of rusting is the manufacture of an iron which 
is so homogeneous that there is little tendency for different spots on 
its surface to develop into postive and negative poles respectively. 
In this direction a great deal of success has been attained through 
the co-operation of the great iron and steel manufacturers and the 
scientific men who have been investigating these problems. Closely 
connected with this attempt is the attempt to find an alloying ma- 
terial which would reduce the dissolving tendency of the iron — 
the solution tension, as it is technically called. Thus alloys of iron 
with 1-2 per cent of nickel rust at a rate which is only 1 to 5 per 
cent of the rate at which pure iron rusts. Most additions, how- 
ever, increase the rate of rusting, so that it is thought that absolutely 
pure iron may not rust at all — an idea that appears to be proven by 
the experiments of J. Kreusler (Berichte der Deutsch phys. Ges., 
6:344), who found that the pure iron he had obtained was not at- 
tacked by muriatic acid. The “lost art” fairy tale has also intro- 
duced itself into this subject : at Delhi, India, there is an iron shaft 
that has stood there since 900 B. C., without any protective coating, 
and it has not rusted in the least; yet iron articles of modern manu- 
facture exposed to the same atmospheric influences have rusted quite 
readily. It is naturally suspected that the iron in the column was 
manufactured by a method which yielded a better iron than that 
obtained by our modern methods. Whether or not it will be pos- 
sible to manufacture a non-rusting iron or iron alloy, is something 
that the future will have to solve; but there seems to be little hope 
for any great discovery in this direction. 
Another possibility that suggests itself for the prevention of rust- 
ing, is the transformation of the surface by means of chemical or 
electro-chemical action so as to render it passive — i. e., inactive. 
When iron is dipped into nitric acid of a certain concentration, the 
surface seems to be transformed so that the acid does not attack it,, 
although under other commonly occurring conditions a very vigorous 
action takes place. Dipping iron into a solution of chromic acid 
has the same effect; and again, when it is made the anode in cer- 
