15 
cream and a yellow or slightly brownish colour. Being st2vile 
it will keep indefinitely, but unless it is of the best quality 
separations will in time take place in the cans.* 
The main outlines of the processes are as follows: 
The fresh milk is first heated in open wells, called fore- 
warmers, to a temperature ranging from 180°F. to boiling 
point. The heat is either applied by injecting steam directly 
into the milk or through a steam jacket around the kettle. 
From there it is drawn into the air-tight vacuum pan where 
the condensation takes place. These pans are of huge size in 
larger factories, so that up to 25,000 pounds or even more of 
fresh milk can be drawn into one batch. The top or dome of 
the pan extends into a condenser consisting of a cylindrical 
chamber usually placed vertically, into which a stream of cold 
water is injected in a spray during operation. The condenser 
is connected by a large pipe with a powerful vacuum pump on 
the floor below which draws off the water together with the 
-condensed vapors from the milk. The vacuum in the nan js 
kept at about 100 to 180 mm. Hg, corresponding with a boiling 
temperature of from 125 to 150 degrees F. The pan haz a 
jacketted bottom and usually two spiral copper coils in its 
lower part through which steam circulates to impart the 
necessary heat. It is fitted with steam gauges, thermometer, 
&@ vacuum gauge, a sampling tube, one or two sight glasses, a 
‘vent-hole or “blow down” valve and a manhole with air-tight 
cover, and an intake pipe for the fresh milk as well as a pipe 
at the bottom to draw off the condensed milk. All steam, 
‘milk and water pipes are, of course, fitted out with the neces- 
sary regulating valves so that the whole becomes a rather com- 
viicated apparatus requiring considerable skill for its opera- 
tion, especially for finishing up a batch exactly at the desired 
concentration. In the case of sweetened milk the nec2ss1ry 
amount of sugar is added during the process of condensation 
*Considerable quantities of condensed milk and skim-milk are also 
sold in bulk. They are designed for more or less immediate use in the 
ice cream, bakery and confectionery business. Sweetened condensed bulk 
milk is usually packed in barrels and will keep according to the degree 
of sugar added. Unsweetened or plain condensed milk is shipped daily 
to the plece of consumption in ordinary cream or milk cans. Its keeping 
quality is that of pasteurized milk. It is condensed chiefly to reduce 
bulk and freight of whole milk, and the degree of concentration can be 
adjusted to the convenience of the consumer and the purpose of its use. 
