Apkil 7, 1S99.] 



SCIENCE. 



519 



boiiate by the silica in mauy shells found asso- 

 ciated with the fuller's earth. 



The Florida and English fuller's earth dif- 

 fer greatly in appearance and to some extentin 

 chemical composition. English fuller's earth 

 has found its analogue in the material discov- 

 ered at Fairburn, near Rapid City, South Da- 

 kota, and Valentine, Nebraska. It is altogether 

 probable that further developments will make 

 the material from these places an important 

 article for use in bleaching cotton-seed oil. 

 There is an interesting difference in the methods 

 of testing the Florida fuller's earth as compared 

 with the English. It is the constant practice of 

 the lubricating oil companies simply to fill large, 

 slightly conical cylinders with the fuller's 

 earth, ground to about 40 mesh, through which 

 the oil is filtered at about the temperature equal 

 to that of boiling water. At first the filtrate is 

 perfectly colorless and, strange to say, lighter 

 in specific gravity and more fluid than the un- 

 filtered oil, a fact which will probably be made 

 use of in chemical separations of the future. Dr. 

 Day is now using this in investigating oils. Ful- 

 ler's earth is used for bleaching refined, golden 

 cotton-seed oil to a light straw color. When 

 the resultant is to be used for white products, 

 such as lard substitutes, the fuller's earth is 

 ground to a fine powder and stirred into the oil 

 slightly above the temperature of boiling water. 

 After a thorough mixing by agitation for a few 

 moments the bleached oil is simply filtered 

 through bag presses. Perhaps the most inter- 

 esting feature of this use of fuller's earth is the 

 very slight difference in the two varieties of 

 fuller's earth in regard to their bleaching ca- 

 pacity, which leads to their acceptance or re- 

 jection. Little regard is paid to chemical anal- 

 ysis, but the tests made by filtration, on a small 

 scale, are most severe." 



William H. Keug. 



geological conference and students' club 

 of haevaed university. 



Students^ Geological Club, February 28, 1899. 

 In considering the ' Law of the Migration of 

 Divides,' Mr. J. M. Boutwell developed this law 

 as stated by Cambell (Journal of Geology, 

 IV, 580), and discussed the amendment to it 



which has been offered by Smith (ISth Annual 

 Report, U. S. Geological Survey, Part II., 472). 



Mr. H. T. Burr described ' A Drainage Pe- 

 culiarity in Androscoggin, Maine.' Andros- 

 coggin Lake, the last of a chain which drain 

 into Androscoggin River near North Leeds, 

 Maine, contains a unique delta, which is situated, 

 not at the head of the lake, but at the outlet. 



The preglacial valley which the lake occu- 

 pies is blocked just below the foot of the lake 

 by glacial debris, which forces the outlet stream 

 to flow backward, against the slope of the 

 country, into the Androscoggin. Thus the fall 

 between the lake and the Androscoggin is so 

 small that at times of flood this main river 

 rises so high as to reverse the flow of the out- 

 let stream. At such times a flood of mud-laden 

 water pours into the lake and deposits its load. 

 Under normal conditions the outflow is incom- 

 petent to remove the material thus brought in. 

 Accordingly the delta has grown, and is still 

 growing, against the normal course of the cur- 

 rent. 



Geological Conference, March 7, 1899. Pro- 

 fessor J. E. Wolff communicated his discovery 

 of ' Hardystonite, a New Mineral from Frank- 

 lin Furnace.' The specimen of ore containing 

 the mineral came from a new working of the 

 Parker Shaft, at about the uine-hundred-foot 

 level. The mineral is tetragonal, and its gen- 

 eral formula is ZnCajSijO;. A complete descrip- 

 tion will be given in the Proceedings of the 

 American Academy of Arts and Sciences. 



Dr. Charles Palache described ' A Method of 

 Enlarging Diagrams,' which has been devel- 

 oped in the Harvard Mineralogical Laboratory 

 within the last few months. It purpose is for 

 preparing large diagrams, from small, straight- 

 line, text diagrams, for lecture use. The instru- 

 ment used is a megascope made by Fuess. This 

 consists of two sets of three mirrors, which con- 

 centrate light upon the diagram. From that the 

 light is reflected through a double-convex lens, 

 which projects the image upon a screen. The 

 diagram is then obtained by tracing the image, 

 thus enlarged to any desired size, and by inking 

 in this tracing. This method possesses a double 

 advantage over photographic enlargements in 

 that it affords a far more satisfactory product 

 and is much cheaper. 



