182 



Remarks on a Paper " On Fluid Cavities in Meteorites ' 

 read by h. hensoldt before the quekett micro- 

 SCOPICAL Club on August 26, 1881. 



By A. de Souza Guimaraens, F.R.M.S. 



{Communicated November 2±th, 1882.) 



I am not aware that any terrestrial rocks have yet been dis- 

 covered showing structure which might be mistaken for that of 

 a meteorite, the iron masses in the Ovifak Basalts being, perhaps, 

 the only exception on record. 



I have placed under one of the microscopes on the table a sec- 

 tion of the specimen described in the above paper. 



I also exhibit — for comparison — a section of ferruginous 

 quartzite from near Upata, South America, and two sections of 

 quartz (one mounted by Mr. Hensoldt) containing fluid cavities 

 with bubbles which have spontaneous motion. 



Upon comparing the so-called " Braunfel's Meteorite " with the 

 quartzite. from Upata, the resemblance existing between the two 

 specimens is very striking. One observes great similarity both 

 in the clear grains and the opaque mineral. Under polarised 

 light the two sections do not show any important difference in 

 structure. 



The proportion of the opaque mineral compared with the clear 

 grains is greater in the Braunfels specimen than in the quartzite, 

 but this difference, being one of proportion only, is really un- 

 essential. 



The similarity between the fluid cavities with moving bubbles is 

 more distinctly seen when comparing the so-called " Braunfels 

 meteorite " with either of the quartz sections I exhibit. The fluid 

 cavities and moving bubbles enclosed in the quartzite show the 

 family likeness, but they are less numerous, smaller, and require 

 at least x 500 for their satisfactory exhibition. 



As to the metallic lustre, of which Mr. Hensoldt seems to make 

 a special feature, it will be found that the jwlished section of the 



