Company Names, addresses, dates1:
Gregor Gerst, 2211 w Pratt, Baltimore MD (1887) [brewer]
Gregor Gerst, 415 E NE, Washington, D.C. (1890) [brewer]
Gregor Gerst, 911 4½ street SW, Washington, D.C. (1891-1894) [saloon]
Gregor Gerst, 900 4½ street SW, Washington, D.C. (1896-1902) [saloon]
According to the 1900 census, Gregor Gerst was born May 1864 in Germany, and came to America in 1883.
Someone named Gregor Gerst was listed as a brewer in Baltimore in 1887, but I'm not certain if it was the same guy.
In Washington DC directories, Gregor Gerst shows up as a brewer in 1890, and a Saloon owner from 1891-1902.
book # 276
This is an aqua 9.25" blob top bottle (with stopper) marked:
front: GREGOR GERST / 900-4½ ST. S.W. / REGISTERED / 1895 / WASHINGTON, D.C.
back: THIS BOTTLE NEVER SOLD