32 



SCIENCE 



[N. S. Vol. XXXII. No. i 



SOCIETIES AND ACADEMIES 



THE GEOLOGICAL SOCIETY OF WASHINGTON 



At the 232d meeting of the society, held at the 

 George Washington University on Wednesday 

 evening, April 27, 1910, Mr. David White exhib- 

 ited specimens of coal from Upper Cretaceous 

 near Newcastle, Colo., as illustrating a coal 

 undergoing rapid devolatilization. The coal eon- 

 tains large quantities of occluded gas which is 

 easily detected by the odor of hydrogen sulphide. 

 The hand specimens exhibited continued for a 

 long time to give off the gas after being broken 

 open and crushed, although they had since collec- 

 tion been exposed to the air for nearly twenty 

 months. 



Regular Program 

 The Sulphides of Iron and their Relations to One 



Another: E. T. Allen and John Johnston. 



(Delivered by Mr. Allen.) Crystallographic 



study by Esper S. Larsen. 



1. Pyrrhotite was formed: (1) by the slow 

 precipitation of ferrous chloride by the vapors of 

 ammonium sulphide, (2) by the direct union of 

 iron and sulphur, (3) by the decomposition of 

 pyrite. The dissociation of pyrite into pyrrhotite 

 and sulphur becomes noticeable at about 500°, 

 and at 700° the vapor pressure probably reaches 

 one atmosphere. The reaction is reversible. The 

 pyrrhotite melts at about 1200°. Cooled in nitro- 

 gen, the product seems to have the composition 

 FeS; cooled in H,S, it absorbs sulphur. Pyrrho- 

 tite appears to be a solid solution of sulphur in 

 FeS. In support of this view, measurable crystals 

 made in the wet were found to have almost the 

 composition FeS. Other lines of evidence are 

 being followed. 



2. Pyrite and marcasite were formed by the 

 reduction of ferrous sulphate by hydrogen sul- 

 phide between 200° and 300°. The pyrite forms 

 in cubes modified by the octahedron; the mar- 

 casite crystals agree closely with the natural min- 

 eral {a: b: c = 0.7660: 1: 1.220). The two disul- 

 phides are generally obtained together; the condi- 

 tions giving rise to each are as yet undetermined. 

 Mstrcasite is an unstable form passing into pyrite. 

 In the dry way the change proceeds slowly at 

 450° without any loss of sulphur. Although the 

 presence of a solvent might be expected to exert 

 a favorable influence on this transformation, no 

 change was observed at 350° in the presence of 

 aqueous sulphuric acid after several days. If the 

 mineral is heated rapidly, considerable evolution 

 of heat is observed between '500° and 600°. At 



this higher temperature a little sulphur is lost 

 and some pyrrhotite formed. Natural marcasite 

 does not change into the denser pyrite when com- 

 pressed at ordinary temperatures at 10,000 at- 

 mospheres. The change of marcasite to pyrite 

 was followed by Stokes's method (Bull. U. S. 

 Geological Survey, 186). The investigation is 

 still in progress. 



A Sketch of the Geologic History of the Floridian 



Plateau: T. Watland Vaughan. 



A brief description was given of the present 

 submarine and subaerial topography of the 

 Floridian Plateau and of the marine deposits now 

 forming in shallow water. The ocean currents, 

 winds, tides, were described, followed by a discus- 

 sion of the principal shore features and drainage 

 lines and a description of the geologic formations 

 and history. The Floridian Plateau was shown to 

 have existed since early Oligocene times and to 

 owe its development to gentle folding due to com- 

 pression from east and west, combined with the 

 usual presence of marine and subaerial erosion 

 and deposition. The role of corals as construc- 

 tional agents was shown to be relatively unimpor- 

 tant at the present time and of still smaller im- 

 portance in the past. The plateau has undergone 

 repeated elevation and depression since Oligocene 

 times, the net result being a gradual extension to 

 the east and to the south. At present the entire 

 western half of the plateau is submerged. 



Edson S. Bastin, 



Secretary 



the AMERICAN CHEMICAL SOCIETY 

 NEW YOEK SECTION 



The ninth regular meeting of the session of 

 1909-10 was held at the Chemists' Club on Fri- 

 day, June 10. 



The annual report of the secretary showed an 

 increase in membership of the section of 93, giving 

 a total of 773 members. 



The following papers were presented: 



Chas. Baskerville and W. A. Hamor : " The Ex- 

 amination of Ethyl Ether." 



H. C. Sherman, E. C. Kendall and E. D. Clark: 

 " An Examination of Present Methods of Deter- 

 mining Diastatie Power." 



E. C. Kendall and H. C. Sherman: "A Study 

 of the Action of Pancreatic Amylase." 



F. J. Pond: "A Case of Iron Corrosion." 

 Arthur E. Hill: "A Note on the Constancy of 



the Solubility Product." C. M. Joyce, 



Secretary 



