What about chemists on US postage stamps?

In my last post, I mentioned I couldn't think of any chemists on US postage stamps at the time, though I mentioned discovering a stamp for Harvey Washington Wiley.  This was due to ignorance on my part.  To set the record straight, in addition to Wiley:

• In 1940, Charles W. Eliot appeared on a 3 cent stamp in the Famous Americans series. 
• In 1947, Thomas A. Edison appeared on a 3 cent stamp, on the 100th anniversary of his birth.  (His first lamp had been celebrated earlier, on a 2 cent stamp in 1929.) 
• In 1948, George Washington Carver appeared on a 3 cent stamp, in the same format as the 1940 Famous American Scientists issue (which originally featured no physicists, astronomers, chemists, or mathematicians).  He later appeared on a 32 cent stamp issued in 1998, part of the Celebrate the Century - 1910s series.  I believe this gives him the honor of being the only chemist to have appeared on 2 different US postage stamps.
• In 1954, George Eastman appeared on a 3 cent stamp, celebrating his 100th birthday. 
• In 1983, Joseph Priestley appeared on a 20 cent stamp, celebrating his 250th birthday.
• In 1993, Percy Lavon Julian appeared on a 29 cent stamp, in the Black Heritage series. 
• In 2009, Linus Pauling (Nobel laureate in both chemistry and peace) and biochemist Gerti Cori (Nobel laureate in physiology/medicine) both appeared on 41 cent stamps in the American Scientists issue of that year, its second such issue.
• In 2011, Melvin Calvin and biochemist Severo Ochoa, both Nobel laureates (in chemistry and medicine/phyisology, respectively), appeared on Forever stamps in the third and final American Scientists issue. 

Finally, in 1988 a physicist associated with Xerox, Chester Carlson, appeared on a 21 cent stamp in the Great Americans series. I should have mentioned him earlier.

Once again, I'm grateful to the website of the Mystic Stamp Company, as well as stampworld.com, and finally this article:

L. R. Caswell, 1990:  American chemists and physicists on postage stamps.  Journal of Chemical Education, 67 (10):  842-847.