304 Caricography: 
is more chemical than washing the ores of silver, as in ‘T'as« 
co, with zacate f and soap, in order to free them from the 
black powder, or oxyd of some metal resembling selenium : 
at least, the Chevalier Mendez and myself met, among these 
ores, the biseleniuret, of silver in small hexagonal tables, 
with the salient angles and corners rounded, as if they had 
been melted ; of a leaden-gray colour, and ductile, as may be 
seen in the Sol, No. 102, Sept. 24th, 1823. It will be bet- 
ter obtained by treating the alloy with sulphuret of antimo- 
ny, on account of the greater affinity between the rhodium 
and the sulphur; a process very successfully employed by a 
man who the last year purified a quantity for 1800 dollars, 
making a secret of it, as if this were an age of mysteries, and 
we were inhabitants of Otaheite. 
This analysis is imperfect, in consequence of the unfortu- 
nate condition of our laboratory, after having been thirty 
years in charge of a chemist like Elhuyar, the discoverer of 
Wolfram and Cerium : it is true, that under the old govern- 
ment he pursued his occupation steadily, through necessity, 
for he who has once had a taste of the experimental sciences, 
cannot possibly ever abandon them. 
igned) ANDRES DEL Rio, 
Prof. of Mineralogy in the College of Mines. 
‘Mexico, Dec. 9, 1824.” 
Arr. XL—Caricography. By Prof. Dewey. 
(Continued from Vol. XI. p. 167.) 
{Communicated to the Lyceum of Nat. Hist. of the Berk. Med. Inst.] 
109. _C. sterilis. Willd. 
sah Sook. » dMfah.Pursh, Eaton, Pers. no. 3. 
a Ell. no. 1. Schw. and Torrey no. 2. 
: Schk. tab. Mmm. fig. 146. 
Spica composita dioica et androgina; spiculis subquinis 
sessilibus approximatis, nunc omnino stameniferis suboblongi 
vel fructiferis ovatis, nune andro is superne vel in- 
rr ‘Stameniferis ovatis ; fructibus distigmaticis ovatis act- 
mimatis vel subrostratis bifidis com sso-triquetris margine 
