188 II. HENSOLDT ON CAVITIES IN METEORITES. 



myself unable to venture a single observation on meteorites, and 

 ■would warn everybody to leave that delicate subject entirely to ex- 

 perts. My experience in meteorites before I knew of the speci- 

 men from Braunfels lias at least been a practical one. Dr. 0. 

 Buchner of Giessen, who is the author of two works on meteorites, 

 often sent small fragments from authenticated meteorites to my 

 father for the purpose of obtaining sections from them. These 

 mostly passed through my hands, and I was also, while studying at 

 Giessen for one and a half years, a pupil of Dr. Buchner. As re- 

 gards the opaque component of the specimen from Braunfels, 

 which, as I have described in my paper, is distributed in the shape 

 of a minute network, its true character is still a puzzle to me. 

 That it is not puro metallic iron, as seemed at first to be the case, 

 I have already mentioned in the paper. But I am equally certain 

 that it is neither Hematite nor any other ordinary ferruginous com- 

 bination, for I am not aware that any similar known substance is 

 capable of receiving and retaining such an absolutely metallic 

 lustre or polish. 



The crystalline and transparent component of the meteoric mass 

 (which contains the fluid cavities) is clearly not quartz, at least not 

 in my humble opinion. The crystals or granules will melt with 

 borax before the blowpipe slowly, and form a transparent glass. 

 They will furthermore dissolve slowly in salt of phosphorus, leaving 

 a skeleton of silica. With a trifling amount of soda they will melt 

 into a white bead, while with a larger quantity they become in- 

 fusible. The crystalline form appears to be Rhombohedral (37° 19') 

 and lamella? cut at right angle to the principal axis show by 

 polarised light the ring system and dark cross. These qualities are 

 certainly not exhibited by quartz. There is only one mineral which 

 possesses similar or identical peculiarities, and that is that singular 

 combination of glucine and silica called Phenacite (Silica 54*90, 

 Glucine 45-10). 



I will not add to the length of this statement by rendering a still 

 more detailed account of the circumstances which gave origin to 

 the opinions expressed in my paper on fluid cavities, or by intro- 

 ducing matters not strictly relevant to the subject. Having re- 

 lated in a condensed form the facts, or what / look upon as the 

 facts, of the case, and the conclusions rightly or wrongly flowing 

 therefrom, I will again briefly refer to the various opinions of 

 adverse critics which have come to my knowledge. To attempt to 



