June 12, 1908] 



SCIENCE 



923 



seum comprise " Gros Ventre Myths and 

 Tales," " Eeligion of the Arapaho " (the latter 

 in the series of the Mrs. Morris K. Jesup Ex- 

 pedition), both by A. L. Kroeber^ and " The 

 Shasta," by Eoland B. Dixon, under the re- 

 sults of the Huntington California Expedi- 

 tion. 



L. P. Gratacap 



SOCIETIES AND ACADEMIES 



THE AMERICAN CHEMICAL SOCIETY 

 NORTHEA'STERN SECTION 



The eighty-fourth regular meeting of the 

 section was held on Friday, April 24, at eight 

 o'clock P.M., at the Tech Union, Boston. 

 About fifty members were present. Professor 

 W. H. Walker, of the Massachusetts Institute 

 of Technology, presented a paper on " The 

 Corrosion of Iron and Steel," with illustra- 

 tions. Pure iron is very rare, but has been 

 prepared by the reduction of pure ferrous 

 oxalate in a vacuum furnace. Small amounts 

 of sulphur, carbon, phosphorus, etc., have 

 marked effects upon the properties and cor- 

 rosion of iron. Iron and steel as made at the 

 present time appear to corrode more rapidly 

 than products made forty years ago. (A 

 sample of iron known to have been exposed 

 to the weather for thirty-four years was shown 

 with little corrosion, while a sample of steel 

 fence wire exposed only six years was very 

 much corroded.) 



The theories of corrosion were outlined as 

 follows : 



Carbon dioxide theory: this was the earliest 

 and has been supported by many authorities 

 and appears in the text-books. The reac- 

 tions proposed are: 4(Fe + H,0 + CO,) = 

 4EeC03 4-4H„ and 4PeC03 + 6H,0 + 0,= 

 4Fe(OH)3 + CO,. This theory appears to 

 account for the facts that corrosion is accel- 

 erated by the presence of carbon dioxide, and 

 that alkalies inhibit corrosion. Certain ex- 

 periments of G. T. Moody appeared to show 

 that no corrosion occurs if carbon dioxide is 

 absent. 



Electrolytic theory proposed in 1903 by 

 W. R. Whitney was based on the following 

 erperiments: Iron immersed in copper sul- 



phate solution became plated with copper, 

 since the copper ions with positive charges 

 have a less electrolytic solution pressure than 

 the iron. Since water is slightly dissociated, 

 its hydrogen acts as a metal, and hence iron, 

 when put into water, dissolves at a rate pro- 

 portional to the concentration of hydrogen 

 ions in the water, and to the relative ease with 

 which hydrogen can be liberated upon the 

 iron. Any acid which increases the concen- 

 tration of the hydrogen ions will thus accel- 

 erate corrosion, while alkalies which decrease 

 the hydrogen concentration will inhibit cor- 

 rosion. 



A repetition of Moody's experiments in de- 

 tail established his observed facts but not his 

 conclusions. Using phenolphthalein, it was 

 found that alkali dissolved from the glass 

 apparatus was sufficient to account for the 

 slow action at first. Immersion of the iron 

 in chromic acid renders the iron passive. But 

 using Jena flasks carrying capillary tubes 

 through the stoppers, and boiling the water, 

 then quickly introducing a piece of iron and 

 boiling again, all oxygen and carbon dioxide 

 was expelled. While still boiling the capil- 

 lary was sealed. After several days no cor- 

 rosion could be observed, but on concentrating 

 the water in a platinum dish, a good test for 

 iron was obtained in each case, using sulpho- 

 cyanate. Numerous repetitions of the experi- 

 ments with elaborate precautions to prevent 

 occlusion of gas in the iron, showed that iron 

 went into solution every time. This supports 

 the electrolytic theory. When bits of iron 

 were immersed in water containing a little 

 potassium ferrieyanide and phenolphthalein, 

 surfaces of opposite polarity on the iron soon 

 became manifest; points at which hydrogen 

 is liberated, i. e., cathode points, became red, 

 since hydroxyl ions are there set free. The 

 anode points became blue, owing to the iron 

 going into solution. The rate of solution of 

 iron in water depends upon the electrolytic 

 solution pressure of the iron and the hydro- 

 gen, upon the osmotic pressure of the iron 

 ions in solution, and upon the " over-voltage " 

 which must be overcome before the hydrogen 

 ions pass from the ionized to the free state. 

 The solution of iron in water becomes con- 



