These antique French "Soda Syphons" or "Seltzer Bottles" are VERY collectible!
They were the "in" item to have in the early 1900's to just after WWII (many of factories that produced these closed due to the war or were utilized for war time efforts).
Gueret was/is an industrial area in France that produced these "etain sans plomb" meaning tin lead free syphons. So not sure if the company derived it's name from the area or what.
The Gueret Brothers did have an exhibit in the 1876 Exhibition "1876 - Centennial Exhibition
565 71 Guéret Bros., Paris.—Soda water machine. 565 72 Logette, Ay (Marne).—Clasps for bottles and machines for applying. 565 73 Maldine, H., Paris—Soda ..." - Catalog 1876 Centennial Exhibition.
I can find where they held patent 107,826 for a automatic index-counter for filling bottles in "The Commissioners of Patents Journals" 28th April 1875. Also Patent 111,270 "a generator for obtaining carbonic acid gas at a small pressure" dated 31st January, 1876.
Bottlers could then purchase these "clasps" (bottle tops) and attach to their own bottles for bottle for others.
I sure can't find anymore information on them after this. Won't be going to France again this year or I would search it there.
The prices can range from $50 to $200 for these pieces. Collected not only for their usage but more often for their beauty!
Any other information on the bottle? Size?