This section is from the book "The Manufacture Of Liquors, Wines, And Cordials, Without The Aid Of Distillation", by Pierre Lacour. Also available from Amazon: Manufacture of Liquors, Wines, and Cordials, Without the Aid of Distillation.
Sugar of milk, or lactin, is found only in milk, of which it forms about five per cent. It is manufactured largely in Switzerland, as an article of food. In preparing it, milk is first coagulated, by the addition of sulphuric acid, and the resulting whey is evaporated to a syrupy consistence, and set aside in a cool place for several weeks, to allow a deposit of crystals. The crystals are then decolorized by ani mal charcoal.
Sugar of milk is a hard, somewhat gritty, white substance, possessing a somewhat sweet taste. In commerce it sometimes occurs in cylindrical masses, in the axis of which is a core, around which the crys tals have been deposited. It dissolves slowly in six parts of cold, and three of boiling water, without forming a syrup; it is but slightly soluble in alcohol. Sugar of milk is not susceptible of the vinous fermentation by the direct influence of yeast; but after the action of dilute acids, which first convert it into grape sugar, it is capable of furnishing a spirituous liquor by distillation. It is well known that both mares' and cows' milk, after becoming sour, are capable of forming an intoxicating drink by fermentation.
Sugar of milk is used to prevent fermentation in syrups, in the proportion of thirty-two parts to one thousand. See Syrups.