TITLES OF rATERS. 4G9 



Mr Gilbert requested Mr Walcott to occupy the chair, and he presented 

 the last paper of the da}^ in the main section : 



SEDIMENTARY MEASUREMENT OF CRETACEOUS TIME 

 BY G. K. GILBERT 



The paper is published in the Journal of Geology, volume iii, 1895, 

 pages 121-127. 



ORGANIZATION OF THE TEMPORARY PETROGRA PIIIC SECTION 



This division of the Society met at 11.30 o'clock a m in the " Williams 

 room " of the geological building. Professor B. K. Emerson was made 

 chairman and Mr Whitman Cross secretar3^ The first ])aper read was — 



THE RELATION OF GRAIN TO DISTANCE FROM MARGIN IN CERTAIN ROCKS 



BY ALFRED C. LANE 



The paper elicited discussion, in which the chairman and E. O. Hovey, 

 J. F. Kemp, J. P. Iddings, G. P. Merrill, F. J). Adams and Whitman 

 Cross participated. 



The second paper was by the same author : 



CRYSTALLIZED SLAGS FROM COPPER SMELTING 

 BY ALFRED C. J-ANE 



[ A hstract'] 



The specimens of sla,G;s exhibited are from the smelting works at Dollar bay, and 

 on Torch lake, in the copper country of upper Michigan. The copper as it comes 

 from tlie mines, if not in masses suitable to be directly smelted into bars, is stamped 

 and washed, and the resulting concentrates or "mineral" is melted into 4ngots. 

 ^lost of the coi)per is found native, therefore, and remains so, but in the process of 

 melting: down a small part is oxidize<l. The waste and scraps of the direct process 

 must therefore be reduced in a cupola furnace. Kelly Island limestone from lake 

 Erie is used as a flux with the coal. It has l)een the custom at times to let the slag 

 from the cupola furnace run into hemis])herical iron i)ots, wliich are two feet in 

 inner diameter and one foot deep and mounted on a carriage. The slag is tlien 

 allowed to cool naturally and the solid contents dumi)ed. In the interior of these 

 pots, within the crust formed by the first cooling, cavities formed, and from these 

 came some of the crystals exhibited. These slags show in general a strong tendency 

 to }>e crystalline, and are very often devitritied to within two centimeters from the 

 outer .surface. 



1. Themost interestingcrystalsare the very large ones of mclilite, one or two centi- 

 meters s(]uar(' and uj) to one centimeter thick. The general form is that of square 

 tablets, but the faces are rounded, exactly as if they were on' th(^ i)oint of being 



