1852.] | 55 
on the wing also differ, the Cumingii having the row from the beak to the pos- 
terior margin. much nearer to the umbonial slope. The folds in the superior part 
of the wing are smaller. This shell is very much compressed at une beaks and 
reminds one of the Margaritana complanata (nobis.) 
Mr. Cuming informs me that he has received several specimens from the 
northern part of China, and that the full grown ones are 5% inches by 63 
inches. I dedicate the specimen to my friend, Mr. Cuming, to whose kindness I 
owe the possession of my specimen. 
= 
The Committee on the following paper of Dr. C. M. Wetherill, re- 
ported in favor of publication in the Proceedings : 
Examination of Molybdate of Lead, from Wheatley’s Mine near Phenizville, 
Chester Clowirain, Pennsylvania. 
By Cuarues M. Weruerity, Ph. D. 
The mineral was given to me by Mr. W. 5S. Vaux, who received it from Mr. 
Wheatley. It was Gounde at his mine near Phenixville, Chester County, Pa. 
The Molybdate occurs with Phosphate of Lead. ‘The crystals (square tables 
modified,) are of /¢ght 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 brown 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 cale spar, or ance: two andy AE of Mohs?’ 
scale. Density ascertained with one gramme of the crystals 5 
A portion of the crystals was analyzed i in the moist way by Aiscaiving 4 in boil- 
ing dilute hydrochloric acid, and separating the crystals of chloride of lead, 
which form on cooling. These erystals were not completely soluble in boiling 
water, but lefta residue i 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 the moist way or before the blow- 
pipe. The earths andalkaline 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 : 
Resolved, That a Committee be appointed to communicate with Com- 
modore Perry, i in relation to making collections of objects of Natural 
History in India, by the U.S. Expedition which is to sail shortly 
for that station. 
Committee—Mr. Cassin, Dr. Ruschenberger and Dr. Elwyn. 
¢ 
