¥ 
Prof. Gmelin’s Analyses. 329 
heam,’’? and with all due deference, I would i inquire, what is 
the difference between this new apparatus, either in principle 
or in application, and the o d fashioned contrivance for dis- 
tinguishing between a true and a counterfeit guinea ? I con- 
fess that | now see none, except that the former is a more 
improved instrument, aud the latter was limited to weighing 
guineas and half guineas only, in air and in water ; but the 
fact that a similar machine was in use years ago, does not in 
my estimation diminish the credit due to Mr. Patten for his 
invention. 
With apes regard, : 
ur obt. servant, es 
S. F. DANA, 
Hanover, N. H., March 18th 1825. 
Arr. XVIII ane of several minerals, by Prof. Gueuin, 
of the University of Tubingen. Communicated by Jeremiah 
Van Rensselaer, M. D. 
Pror. yeaa 
EAR SIR, 
I wave much pleasure in offering you an extract of a letter 
just received from my friend Prof. Gmelin, dated, “ Univer- 
sity of Tubingen in Wurtemberg, Jan. 6th, 1825.’ 
Yours truly, 
JER. VAN RENSSELAER. 
New-York, Am “se 1825. 
“* Since my last to you I have been much ees | with 
analyse s, ai: shall give you some of the results obtai 
*‘[ have discovered a beautiful mica in large Gare t to be 
a crystallized Lepidolite—that is to say, to contain lithion. 
It is composed o 
CS ee - - - 52.254 
Alumina ” - 28.345 
Ox. of Manganese, "7 - 3.602 
oe - - . &.903. 4 
Lithio - - k= 4.792 
Fluoric "Acid, - - - 3.609 
99.505 
Vor. IX.—No. 2. 42 
