Company Names, addresses, dates ¹
  Eisenbeiss (saloon) , 395 H Street North, Washington DC (1864-1865)
  Eisenbeiss & Seitz (brewery), Pa Ave between 12th and 13th Streets, Washington DC (1866)

Notes:
Adolph Eisenbeiss (1831-1866)² was a weiss beer brewer¹.
He first shows up in DC city directories as a Sutler in the 1863 directory, presumably for the Union army. The 1864 and 1865 directories list him as owning a Saloon at 395 H Street. By 1866 he was head of the brewing company called Eisenbeiss & Seitz, but he passed away due to a gun accident in October of that year³.
A Tax record from May of 1866 listed Eisenbeiss & Seitz as brewers at 247 & 249 PA Avenue, with 6 barrels of beer/weiss brewed, and 6 barrels sold. For that they paid $6 tax. ⁴

I could not find any information out about Eisenbeiss's business partner named Seitz.
But I did find an article indicating that his wife, Rosa Marie Eisenbeiss (1837-1909)⁵ ran his business after he passed away. A newspaper ad⁶ that ran in 1867 said:
    "Mrs. ROSA EISENBEISS claims all bottles and jugs marked "Eisenbeiss & Seitz", "A. Eisenbeiss", "R.A. Eisenbeiss", and "Fegh", Pennsylvania avenue No 247 and 249, Washington DC".
The 1870 US Census lists the occupations of Rosa and her new husband (Benedict Volker) as "Keeps Restaurant", and the occupation of one of the boarders in their house (Carl Myerhoffer) as "Brewer", so maybe they were producing beer at their restaurant at that time⁷.

I beleive the stoneware bottle below, marked "R. EISENBEIS", is attributed to Rosa Eisnebeiss.

Eisenbeiss & Seitz Bottles:

book # 30 (in the Stoneware section) This is a 7" brown stoneware blob-top bottle imprinted: shoulder: EISENBEISS & SEITZ

book # (unlisted - in the Stoneware section) This is a 7.2" tan stoneware blob-top bottle imprinted: shoulder: R EISENBEIS It only has one 'S' at the end, but I believe this is attributed to Rosa Eisenbeiss.