902 



SCIENCE 



[N. S. Vol. XXV. No. 649 



are in favor of the mutation theory of the 

 origin of plant species. ' The Coincident Dis- 

 tribution of Eelated Species of Pelagic 

 Organisms as illustrated by the Chatognatha ' 

 is by Charles A. Kofoid, who shows that there 

 is a tendency for two species of a genus of 

 this group to occur in one locality and not 

 elsewhere, and considers that this casts some 

 doubt on the universality of operation of isola- 

 tion in the evolution of species. E. A. An- 

 drews describes at some length ' The Attached 

 Young of the Crayfish, Cambarus clarhii and 

 Cambarus diogenes ' and considers their bear- 

 ing on the question of the evolution of the 

 species. 



The American Museum Journal for May is 

 mainly devoted to an article by Clark Wissler 

 on ' The Douglas African Collection ' recently 

 acquired by the museum through the gen- 

 erosity of some of its friends. 



The Bulletin of the Charleston Museum, for 

 April contains an account, by Ezra Brainerd, 

 of ' A Visit to the Grave of Thomas Walter,' 

 one of the earliest of American botanists and 

 the author of Flora Carolina. A pleasant re- 

 sult of this visit has been the taking of steps 

 for the preservation and protection of the 

 grave. 



The Peabody Museum of Natural History, 

 Yale University, has just issued Guide No. 1 

 on ' The Evolution of the Horse Family,' by 

 Richard S. Lull, and based on the valuable 

 material mainly brought together by Professor 

 Marsh, and recently admirably arranged and 

 labeled by Dr. Lull. 



SOCIETIES AWD ACADEMIES 



THE AMERICAN CHEMICAL SOCIETY. NEW 



YORK SECTION 



The seventh regular meeting of the session 

 of 1906-'07 was held at the Chemists' Club, 

 108 West 55th Street, on May 10. 



The following papers were presented: 

 The Causes of the Corrosion of Iron and 



Steel: W. H. Walker. 



With the ever-increasing use of iron and 

 steel, the conditions which limit the life of 

 structures made from these materials, assume 



great importance. To few subjects have been 

 devoted so much elaborate investigation with 

 such conflicting results. Of the many papers 

 which have been published and theories ad- 

 vanced as to the cause of corrosion, the three 

 following are of special importance: Calvert, 

 after a series of experiments came to the con- 

 clusion that ordinary corrosion or rusting of 

 iron could take place only when all of the 

 three reagents, carbon dioxide, water and oxy- 

 gen were present. This opinion was univer- 

 sally accepted until in 1903 Whitney showed 

 that corrosion was a purely electrochemical 

 phenomenon and would take place in water 

 in the absence of both oxygen and carbon 

 dioxide, although for the formation of the so- 

 called rust, oxygen was necessary. A year or 

 so later Dunstan and his co-workers pub- 

 lished the results of their work from which 

 they concluded that Whitney was at fault and 

 that iron was not corroded by water in the 

 absence of oxygen and carbon dioxide. They 

 believed the action of oxygen on iron to be a 

 direct one, with the intermediate formation of 

 hydrogen peroxide, and that in ordinary cor- 

 rosion electrochemistry does not play a part. 

 Following this paper came one from Moody, 

 of Kensington, England, who took issue with 

 both Whitney and Dunstan and describes 

 experiments which he thinks conclusively 

 prove that no corrosion of any kind takes 

 place in the total absence of carbon dioxide. 



Work recently carried on at the Institute of 

 Technology substantiates Whitney's claim in 

 so far that there is a slight corrosion of iron 

 in pure water although if oxygen and carbon 

 dioxide be most carefully eliminated, the pres- 

 ence of dissolved iron can be detected only 

 with the greatest care, and possibly if these 

 two constituents were absolutely removed, no 

 iron would be dissolved. There is a tendency, 

 however, for iron to pass into solution and for 

 hydrogen to precipitate out in a way analo- 

 gous to the action of iron in a copper sulphate 

 solution. Unless oxygen or some other sub- 

 stance be present to unite with the hydrogen 

 when set free upon the surface of the iron, the 

 action, if it starts at aU, very soon ceases. To 

 remove this hydrogen and thus accelerate the 

 action is the function of oxygen in corrosion. 



