264 ROCHESTER ACADEMY OF SCIENCE. [Juiie 21, 



The nomination of Dr. Moxtgomery E. Leaky for Secretary of 

 the Academy was taken from the table and he was duly elected. 

 Professor E. L. Nichols, of Cornell University, was elected a cor- 

 responding member of the Academy. Dr. C. W. La Salle and Dr. 

 F. H. Sowers were elected active members. 



The following paper was read : 



A NEW METHOD OF ETCHING IRON METEORITES, WITH 



SPECIAL ADAPTATION FOR PHOTOGRAPHIC 



OR PLATE PURPOSES. 



By H. L. Preston. 



It has been my pleasure for many years past, in my connection 

 with Ward's Natural Science Establishment, to have the supervision 

 of the cutting, polishing and etching as well as the general care of 

 their large collection of Meteorites. 



I have been constantly annoyed by the tendency of the etched slices 

 to rust or corrode. This rusting causes continual work, in cleaning, re- 

 polishing and etching of the masses, which means not only a loss in time 

 spent thereon, but a constant decrease in the weight of the specimen as 

 well, which, as the value of meteorites are estimated at so much per 

 gramme, means a net loss of many dollars per year. In experiment- 

 ing by various methods to overcome this, I have at last come upon a 

 process, which as far as I know is entirely new for this purpose. 



Meteorites are generally considered as consisting of three nickel- 

 iron alloys, viz. kamacite, taenite and plessite, as first shown by 

 Reichenbach. More recent investigations however, by Davison, tend 

 to show that there are really but two alloys, and that the plessite is 

 composed of very narrow alternating bands of kamacite and taenite. 



The chemical composition of these alloys as far as the Fe and Ni 

 alone is concerned, according to Davison is 



Kamacite Fe. 93.09 Ni. 6.69 



Plessite A Fe. 92.81 Ni. 6.97 



B Fe. 72.98 Ni. 25.87 



Taenite Fe. 74.78 Ni. 24.32 



(Mr. Davison in analyzing the plessite separated it into two parts, 

 the above analysis will show how close part A comes to the kamacite 

 and part B to the taenite, thus strongly suggesting that it is composed 

 of alternating bands of each.) 



