Company Names, addresses, dates¹:
  Ross & Otto, 6th west corner C North (1864)
  Ross & Otto, 11th west corner B north (1865-1867)
  George Otto, 11th west corner B north (1868-1869)
  George Otto, 609 B NE (1870-1873)
  George Otto, Mass Ave near 6th street NE (1874-1880)
  George Otto, 618 Mass Ave NE (1881-1886, 1888)
  Elizabeth Otto, 618 Mass Ave NE (1887)

Notes:
John W. Ross (b: 1842 in Maryland) and George Otto (b: 1842 in Bavaria, d: 1883) started this company as "Ross & Otto".
The 1870 census listed John Ross as living in the same house with George Otto. In the 1880 census, they were living in separate households, although there was a Nicholas Ross in George Otto's house listed as a son-in-law, so there seems to have been a marraige between the Ross & Otto families.

The December 9, 1865 Daily National Republican newspaper has an article that says George Otto shot an African American man. ²
Otto was found guilty of assault & battery with intent to kill, and sentenced to 2 years in a penitentiary.³
But in May of 1866, Otto was pardoned by the President, on the recommendation of the jurors who convicted him, and the Mayors of Washington & Georgetown.⁴

1868 is the first year that the city directory listed the company name as simply "George Otto".
George Otto and George Bauer invented an improved bottle fastener and patented it in 1871 (US patent # 116742) - see the copy of the patent near the bottom of this web page.

George passed away on April 11, 1883, after which time his wife Elizabeth Otto took over the company.⁵ The company seems to have kept George Otto's name after he died. The city directories list the name "George Otto" in 1884, 85, 86, and 88, with the name "Elizabeth Otto" showing up only in the 1887 directory.

Historical & Commercial Sketches of Washington, compiled by E.E. Barton in 1884, says that the dimensions of the building were 20 x 40 feet, and that about 7 hands were employed and 3 wagons used to deliver the products. It also says that they bottled soda, porter, sarsaparilla, cider and Capitol ginger ale. ⁵

I'm not sure if/how George Otto is related to Henry Otto , another DC bottler. The 1880 census lists Henry as the son of Frederick Otto, however Frederick & family were living in the same house as George Otto. My guess would be that George was Henry's nephew.
In 1884, Henry Otto was a foreman at George Otto's bottling establishment (owned by Elizabeth Otto at the time), and he left to form his own company⁶.

	book # 611 This is a dark green 7" squat blob top bottle embossed: front: ROSS & OTTO / WASHINGTON / D. C. back: THIS BOTTLE IS / NEVER SOLD
	book # 612 These 3 short-blob bottles are different colors, but they're all about 7" tall and embossed the same. From left to right, they are dark green, aqua, and blue/aqua. They are embossed: front: ROSS & OTTO / WASHINGTON / D C back: R&O / THIS BOTTLE IS / NEVER SOLD
	book # (unlisted) This is a bluish-aqua 7.25" short blob top bottle embossed: front: R & O / WASHINGTON / D.C.

	book # 469 This is an aqua 7.5" blob top bottle embossed: front: GEO. OTTO / WASHINGTON / D.C. back: G O / THIS BOTTLE IS / NEVER SOLD
	book # 469 This is similar to the bottle above, except it's shorter (7") and has a different shaped blob top. It is embossed: front: GEO. OTTO / WASHINGTON / D.C. back: G O / THIS BOTTLE IS / NEVER SOLD
	book # 469 This is similar to the bottles above, except it's color is an unusual shade of aqua, or maybe even citron. It's a 7" blob top embossed: front: GEO. OTTO / WASHINGTON / D.C. back: G O / THIS BOTTLE IS / NEVER SOLD
	book # 471 This is an aqua 6.6" Hutchinson with a cigar-band slugplate, embossed: cigar-band slug plate: GEO. OTTO / WASHINGTON / D.C. base: No 2 I photographed it from an angle to show-off the unusual slug-plate.
	book # 472 This is an aqua 6.1" Hutchinson bottle embossed: round slug plate: GEO. OTTO / WASHINGTON / D.C. The word "WASHINGTON" is embossed in a wavy pattern.