Glass bottle with a glass stopper that is covered with a piece of leather. Clear liquid inside. Handwritten label reads "Concentrated Spirit of Minderens". Second label has handwritten instructions "Half a teaspoonful in a teablespoonful of water" and printed company name "Twinberrow, Dispensing Chemist, 2, Edwards Street, Portman Square." Spirit of Mindererus Med., an aqueous solution of acetate of ammonium; -- named after R. Minderer, physician of Augsburg. (Webster 1913)
Mindererus Spirit. The liquor, or solution, of ammonium acetate (MH: CH3COONH4 , still used as a food additive today) is sometimes called spirit of Mindererus. It promotes perspiration and is generally included in a fever mixture. The dose is 2 to 6 drachms. (From: The Illustrated Family Doctor - A Handy and Authoritative Guide to Essential Medical Knowledge and the Maintenance of Good Health - London 1934.)
Savory 1836, p.83: “Spirit of Mindererus. When assisted by warmth and plentiful dilution, this preparation is an excellent and powerful sudorific in colds, fevers, &c.; and as it operates without quickening the circulation or increasing the heat of the body, it is admissible in febrile and inflammatory diseases, in which the use of stimulating sudorifics are attended with danger. It may be taken to the extent of half-an-ounce two or three times a-day in a glass of any fluid. The following draught may be taken at night on going to bed to allay the restlessness and irritation that often attends a common cold:--

Take of Mindererus’s Spirit
Camphor Julep, each six drachms;
Syrup of Poppies, one drachm;
Antimonial Wine, fifteen drops;

Mix.
Externally, Mindererus’s spirit is employed as a lotion to inflamed surfaces, and when diluted with rose-water, it is an excellent collyrium in chronic ophthalmia; and, still more largely diluted, is occasionally used as an injection of this diaphoretic medicine be not aided by warmth, it is apt to act upon the kidneys, and prove diuretic.”