POSTSCRIPT. 
Iodine in Saratoga mineral water. 
TO PROF. SILLIMAN. 
New York, Grand street, 3mo. 25, 1829. 
My dear friend—My young friend William Usher, a stu- 
dent of Rutgers Medical College, has just given me an occu- 
. Griscom. 
ERRATA. 
Page 53, line 13 from top, for principal read principle. 
: , * 10 from bottom, do. do. 
« 94, © 19 from top, for light read slight. 
