u 

 u 



C. U. Shepard's Reply to F. A. Genth. 43 



Dr. Genth gives tlie calculated percentage of tlie pure mineral 

 thus: 



SPbO, - - - 334-S 80-44 p. c. 



eAl^Os, - - - 308-0 2801 



3P05, - - - 2140 . 19-46 



27HO, - . - - 243-0 22*09 



1099'8 100-00 



T^o\v if the reader Avill take the trouble to compare the amor- 

 phous structure of the Hitchcockite, ^vith the crystaHine charac- 

 ter of Dr. Genth's mineral, but more especially, if he will notice 

 the widely difTerent hardness, gravity and blowpipe properties of 

 the two, he will be satisfied, that Dr. Genth has not examined 

 the Hitchcockite, at all. And still farther, if he will compare 

 Dr. Genth's results with the descriptions of the plumbo-resinite, 

 he will find nothing in them, really inconsistent with the suppo- 

 sition, that he has mistaken an impure specimen of my plumbo-' 

 resinite for the Hitchcockite! Even his analyses accord with 

 this view, as will appear from the following results of the re- 

 searches of Damour, upon the plumbo-resinite of Huelgoet: 



/ 



Phosphoric acid, 

 Oxyd of lead, 

 Alumina, 

 Peroxyd of iron, 

 Lime, 



Chlorid of lead, 

 Sulphuric acid, 

 Water, 



8-06 

 3510 

 34-32 



0-20 



o-so 



2-27 



0-30 

 18-tO 



99*76 



The mineralogist will hardly need to be reminded, in this con- 

 nection, that plumbo-resinite does not rank among the most 

 indubitable of our species. It is even doubtful whether it is any 

 thing more than a variable mixture of Fischerite or Hitchcock- 

 ite, with Pyromorphite : while the disputed Cherokine stands, 

 perhaps, upon the same precarious footing, though it appears for 

 the present, to possess a set of properties, not reconci able with 

 the normal varieties of plumbo-resinite. 



Dr. Genth calls in question my discovery of Lanihdnite at Can- 

 ton, in these rather remarkable words: ''Prof. C. TJ. Shepard 

 states (Report on the Canton Mine), that he has^ observed this 

 mineral at the Canton raine ; he does not inform us, hoAvever, 

 what induces him to take the pink-colored crystals for lanthanite. 

 I have not been able to procure a specimen of it, and also did not 

 succeed in finding any indications of minerals containing cerium 

 or lanthana, from the decomposition of which the lanthanite 

 could have been formed." 



It was natural to have supposed, that the simple mention of a 

 mere mineralo^rical curiositv, was all that could have been looked 

 for in an economical report, I have, however, had reference to 



