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.
Keep in well-stoppered bottles. It is obtained by treating black oxide of manganese with hydrochloric acid. The salt is in granular, or, when slowly evaporated, in tabular crystals of a pale rose-red color. It is soluble in alcohol, and requires at ordinary temperature about 2 1/2 parts of water for solution. A ready-made solution of 10 per cent, strength must be prepared by dissolving 15.71 parts by weight of manganese chloride in 84.29 parts of distilled water. Filter. Specific gravity 1.091 to 1.092 at 15° C. Proportion 10 to 1. Manganese chloride serves to produce manganese carbonate or phosphate within the mixture in fountain by the aid of carbonate or phosphate of soda, etc. Its solution is added after the atmospheric air has been removed, as the carbonate or phosphate of manganese would readily be oxidized and cause turbidity. A solution of manganese chloride is not oxidized on exposure to air; it can therefore be kept in stock.