628 RECORDS. 



SECTION OF GEOLOGY AND MINERALOGY. 

 February 20, 1899. 



Section met at 8 P. M., Professor Kemp presiding. The min- 

 utes of the last meeting of Section were read and approved. 



The Chairman announced his great regret that the speaker for 

 the evening, Professor R. D. Sahsbury, who was to read a 

 paper on "The Surface Geology of New York and Vicinity," 

 was unavoidably detained in Chicago, and had telegraphed his 

 regrets and apologies. 



Dr. Wallace G. Levison gave a brief preliminary note on re- 

 cent experiments made by him in regard to the emission of 

 " uranium " or " Becquerel " rays by certain uranium minerals, 

 especially uraninite. He wrote and drew figures on a card with 

 glue and covered the designs with powdered uraninite which 

 adhered to the marked portions. This card he then placed upon 

 a photographic plate that was completely wrapped in black 

 paper, and protected from contact with the uraninite and from 

 exposure to light-rays ; and in two or three days a sharp image 

 was produced on the plate. Further experiments had enabled 

 him to reduce the time. He was still engaged in these tests, 

 and had not intended to speak of them at present, but did so on 

 this occasion, as the regular paper had failed and the ev^ening 

 was open. 



The Chairman, Professor Kemp, stated that in Professor Sal- 

 isbury's absence, he had undertaken to occupy a part of the 

 time and would give a paper " On the Titaxiferous Magxe- 

 TiTES." He described the two great groups of magnetites long 

 since recognized as with or without the presence of titanium, and 

 the mode of occurrence of the two, the purer magnetites chiefly 

 in granitic and gneissoid rocks, and the titaniferous ones closely 

 associated with rocks distinctly igneous, and apparently separated 

 out from them in the process of cooling. He then discussed the 

 theories as to the manner in which the titanium was combined, 

 and the formulas proposed to express the relations which are 

 still matters of some uncertainty. The geographical occurrences 



