CONDENSED MILK. The manufacture of condensed milk is thus described :—" When the milk is brought intu the factory it is carefully strained, placed in cans or pails, which are put into a tank of water kept hot by steam coils. When hot it is transferred to larger, steam-heated, open vessels and quickly brought to a boil. This preliminary heating and boiling has for its object the expulsion of the gases of the milk, which would cause it to foam in the vacuum pan, and also to add to the keeping quality of the milk by destroying the mould germs.
A second straining follows, after which the milk is transferred to a vacuum pan, where, at a temperature below 160° Fahrenheit, it boils, and is rapidly concentrated to any degree desired. The vacuum pan employed is a close vessel of copper, egg-shaped, about six feet high and four and a half feet in diameter. It is heated by steam coils within and a steam jacket without, enclosing the lower portion. In one side of the dome is a small window
through which the gas illuminates the interior, while on the oppo site side is an eye-glass through which the condition of the con tents may be observed. The pan is also provided with a vacuum guage and test sticks.
Much of the milk used in cities is simply concentrated without any addition of sugar. The process of concentration is continued in the vacuum pan until one gallon of milk has been reduced to little less than a quart—one volume of condensed milk corres ponding to about four and three-tenths volumes of milk. Con densed milk intended to be preserved any length of time has an addition of pure cane sugar made to it during boiling, and is usually put up in sealed cans. This sugared or " preserved " milk will keep for many years."