Kendra,
 The collection I am working on had a bottle similar if not identical to the one 
you have embossed "six to one gallon" on its base. We found a reference on 
page 616 of "Behind the Seawall: Historical Archaeology along the San 
Francisco Waterfront" by Pastron et al (1981). They identified it as an export 
lager bottle made by W.M. McCully & Co. of Pittsburg reportedly from 1875.  
Info on W.M. McCully & Co can be found on pg 351 of "Bottle Makers and Their 
Marks" by Toulouse, which will give you dates of 1841-1886. Hope this was 
helpful.
Cheers,
Phil Glover