Marybeth,
 
There are three possible explanations for the purple color:
 
1. The color might be the result of the contents of the bottle.
2. The bottle may have been intentionally made of purple glass.
3. The bottle was originally colorless and turned purple due to infrared solar radiation.
 
The first would be unusual, and I only mention it because you discussed stains from the bottle.  Nothing in the bottle's manufacture would account for staining of your hands.
 
The second is unlikely; few bottles were intentionally made of purple glass, although several types of tableware were intentionally purple.
 
Solar radiation creates an amethyst color in glass that was originally colorless if the formula contained manganese dioxide.  The volume of manganese in the glass mixture determines how long the solarization takes.  Manganese was used as a decolorant at least as early as 1812, although it was not common in U.S. glass until ca. 1880.  Manganese use was at its peak between ca. 1890 and ca. 1920, although some use extended until at least 1933.
 
Bill


 
 
 
 
Bill Lockhart
Professor of Sociology
New Mexico State University
Alamogordo, NM
(575) 439-3732
>>> Marybeth Tomka <[log in to unmask]> 6/27/2012 2:33 PM >>>
Hey Folks,

We are working on cataloguing materials from a privy on the edge of the
red light district in San Antonio, Texas.  We have a small purple bottle
that stains our hands when touched.  The bottle is only missing the neck
and lip, has turned completely purple and  there is still some dried
material in it.  I was hoping someone out there would know what color
bottles they would have used for this material and if the bottles would
have discolored over time.  Also, does anyone know a test we can perform
to find out if this is really gentian violet.  

Thanks in advance.

Marybeth 

Marybeth S.F. Tomka, M.A. 
Laboratory Director and Curator 
Center for Archaeological Research 
The University of Texas at San Antonio 
State Certified Curatorial Repository 
One UTSA Circle 
San Antonio, Texas 78249 
(210) 458-7822 
(210) 458-4397 Fax 
http://car.utsa.edu/ 
. . . herding cats in a forest of catnip . . .