1898.] PRESTOX ETCIIIN'G IRON METEORITES. 267 



The iron in this condition can be thoroughly cleaned and dried, 

 the moisture being driven out of the iron to prevent rusting. It is 

 then ready for the camera. The strong contrast between the kama- 

 cite of silver color and the brick red taenite gives a negative that is 

 strong and sharp, the taenite taking black, the kamacite light, which 

 is the effect desired, as the kamacite on an etched surface is always 

 much lighter in color than the taenite and plessite. It further places 

 the iron in a condition to study even the minutest complicated struc- 

 ture of the Widmanstatten figures without a strain on the eye as in 

 the case where the iron is uncolored. 



The copper coating can then be removed by soaking the speci- 

 men in concentrated ammonia ; then we wash with alcohol to evapor- 

 ate the moisture, heat the iron thoroughly, coat it with parafine, and we 

 have a beautifully etched meteorite of even color that will remain 

 for years without discoloring. 



It will be readily seen that the advantage of this process in pho- 

 tography will be more effective in those irons in which the figures 

 are composed of narrow laminae such as the Grand Rapids, Mungindi, 

 Hamilton Co., etc., in which you can place your object in such a 

 position as to get rid of the evil effects of reflection. In irons of broad 

 laminae such as Canon Diablo, Bendego, Wichita Co., etc., the 

 reflection on the broader plates of kamacite would be such that the 

 photograph, as far as the figures are concerned, would not be as 

 sharp and decided as in the former case. 



Previously we had to depend entirely upon reflection for a good 

 result in photographing etched surfaces of meteorites, while in this 

 process the result depends upon the contrast in color caused by the 

 deposit of copper. 



The paper was illustrated by a number of specimens of meteorites. 



Professor H. L. Fairchild gave a lecture upon 



ANIMAL SELF-DEFENSE 

 illustrated by lantern views. 



October ii, 1898. 



The meeting was held at the Reynolds Library, President 

 Fairchild in the chair ; twenty persons present. 



