This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Liquid Extract (Liebig's Formula). - Half a pound of fresh meat is finely chopped and macerated for one hour with 1 pint of cold distilled water, to which 4 drops of hydrochloric (muriatic) acid and from 30 to 60 grains of table salt are added. The mass is then displaced on a colander, a little water being added, until 1 pint of percolate has been obtained; filter. The clear liquid has a red color, agreeable odor and contains the albuminoids of the meat in solution.
Take 1 part of meagre beef, finely chopped, and 8 parts of cold water, heat gradually (this is important) to boiling; filter. If the fatty portions of the beef have not been removed, the extract will not keep.
The commercial beef extract is concentrated by evaporation in steam-pans, a current of air being continuously passed over the surface. On a small scale the liquid extract is concentrated by evaporating on a water bath. The concentrated extract of meat is of a brown color, usually somewhat granular, and has a pleasant odor suggestive of roasted meat, and a characteristic, distinctly saline and acidu-ous taste. It is completely soluble in water, yielding a clear solution, which on the addition of a little table-salt has the flavor of beef-broth.