1852.] " 55 



on the wing: also differ, the Cumhigii having the row from the beak to the pos- 

 terior nnargin much nearer to the umbonial slope. The folds in the superior part 

 of the wing are smaller. This shell is very much compressed at the beaks and 

 reminds one of the Margaritana compla/iata (nobis.) 



Mr. Cuming informs me that he has received several specimens from the 

 northern part of China, and that the full grown ones are 5h inches by 6i 

 inches. I dedicate ihe specimen to my friend, Mr. Cuming, to whose kindness I 

 owe the possession of my specimen. 



The Committee on the foUowincr paper of Dr. C. M. Wetherill, re- 

 ported in favor of publicatiou in the Proceedings : 



Examination of Mohjbdate of Lpad, from Wkeatley^s Mine near Phanixville, 



Chester County^ Pennsylvania , 



By Charles M. Wetherill, Ph. D. 



The mineral was given to me by Mr. W. S. Vaux, who received it from Mr. 

 Wheatley. It was found at his mine near Phcenixville, Chester County, Pa. 

 The Molybdate occurs with Phosphate of Lead. The crystals (square tables 

 modified,) are of light red color. Lustre adamantine, translucent, streak white. 

 Before the blow-pipe on charcoal decrepitates, and fuses with reduction of lead. 

 On platinum wire with borax in the outer flame is dissolved to a trans- 

 parent glass, yellow while hot, colorless on cooling; in the inner flame, the bead 

 becomes deep brov^-n when cool. In salt of phosphorus in the outer flame, the 

 same reaction occurs as with borax ; in the inner flame the green color charac- 

 teristic of Molybdena appears. It dissolves almost completely in nitric acid, 

 and in hydrochloric with a residue of chloride of lead ; these solutions are yellow. 

 Hardness between selenite and calc spar, or between two and three of Mohs' 

 scale. Density ascertained with one gramme of the crystals 5-6. 



A portion of the crystals was analyzed in the moist way by dissolving in boil- 

 ins: dilute hydrochloric acid, and separating the crystals of chloride of lead, 

 which form on cooling. These crystals were not completely soluble in boiling 

 water, but left a residue in small quantity, apparently silica. The solution fil- 

 tered from the chloride of lead, treated with sulphuretted hydrogen, gave a dark 

 brown precipitate, composed of the sulphurets of lead and molybdenum, the latter 

 was dissolved from the lead by hydrosulphuret of ammonia. The filtrate from the 

 sulph. hydrogen precipitate contained a trace of iron. 



I was not able to detect chromium either by Ihe moist way or before the blow- 

 pipe. The earths and alkaline earths were also absent. 



I am not aware that a red molybdate of lead of American locality has been 

 described. 



The following resolution was unanimously adopted : 



Resolved, That a copy of the Proceedings, as far as published^ be pre- 

 sented to Dr. Henry A. Ford, of Liberia, Africa, in return for his re- 

 cent valuable contributions to the Academy, from that country. 



Dr. Elwyn offered the following, which was adopted : 



Rcsolvedj That a Committee be appointed to communicate with Com- 

 modore Perry, in relation to making collections of objects of Natural 

 History in India, by the IT. S. Expedition which is to sail shortly 

 for that station. 



Committee Mr. Cassin, Dr. Ruschenberger and Dr. Elwyn. 



