ABSTRACTS OF PAPERS BY J. F. KFMP AND A. C. LANE. 6 



in rotation, during successive meetings, to the head of the program. Tlic 

 adoption of this rule will enahle the Fellows to determine beforehand 

 the relative position of their papers in the program. In accordance with 

 this plan, the papers on petrograph}^ and mineralogy at this meeting 

 headed the list. 



The reading of papers was declared in order, and the first title an- 

 nounced was as follows : 



TJIE yiCKEL MiyE AT LANCASTER GAP, PEIVNSYLVAi\IA, AND THE PYRHnOTJTE 

 DEPOSIT AT ANTHONYS NOSE, ON THE HUDSON 



BY J. F. KEMP 



[Abstracll 



The paper described, with maps, sections, lantern views and specimens, these 

 two deposits of nickeliferous pyrrhotite. The former is on the contact between 

 a great intruded lens of some original, basic, intrusive rock— now altered to a 

 mass of coarsely crystalline, green hornblende (i. e., it is an amphibolite) — and its 

 walls of mica-schist and pegmatite. The latter is a lens or pod of the tyi)e familiar 

 in the iron mines of the highlands of New York and New Jersey, and is in acidic 

 gneiss of the oomposition cf granite. The question of origin was discussed with 

 especial reference to magmatic se])aration, and with comparisons with nickel ores 

 elsewhere in America and in Norway. 



Remarks were made by Alfred C. Lane, W. N. Rice and Frank D. 

 Adams. 



This paper will be printed in full in the Transactions of the American 

 Institute of Mining Engineers, Bridgeport meeting, October, 1894. 



The second paper was — 



A CONNECTION BETWEEN THE CHEMICAL AND OPTICAL PROPERTIES OF 



AMPHIBOLES 



IJY ALFKED C. LANE 



\_A}>s(m(i^ 



The folluwin.i^' law seems to ai»ply to all the hornblendes, so far as the data go, 

 with one excei)tion : 



The amount of Na./; contained —^)(^/ 17 (0.012— (the birefraction of the ortho. 

 pinacoidal section) ), said birefraction being considered + or — according as the 

 character of the extinction is + or — . 



The data are limited ; the constants only a[)pro\iinate. It is therefore very de- 

 sirable that those making hornl)lende analyses should also measure this ])irefrac- 

 tion. It also remains to be seen how far this law holds, for it cannot be expected 

 to be true throughout the grouj). 



In the absence of the author, the tiiird paper was held in its place by 

 vote, and it was read Ijy J. F. Kemp. 



