The corrosion rate of annealed pure iron in is increased by alloying several hundredths per cent of various nonmetallic elements in the sequence B, N, As, C, S, P. The addition of 0.02% N increases the rate by a factor of only 1.3, whereas for 0.02% S or P the corresponding factors are 23 and 31, respectively. Small amounts of As up to about 0.1% increase the rate; larger amounts, up to at least 0.27%, decrease it. Tin in the amount of 0.1% or more decreases the corrosion rate below that of iron itself; it similarly decreases corrosion of iron in citric or malic acid. Cold work alone has relatively little effect on the corrosion rate except with iron containing carbon, for which the effect is large. Polarization measurements show that hydrogen overvoltage of the added element itself, or as associated with Fe, is the generally important factor controlling corrosion; in some cases change of anodic polarization also enters.