PLAIN CONDENSED BuLK MILK 165 
lished density, usually condense the milk to a point shehtly 
bevond that desired. Then, after superheating, they determine 
the amount of water required to reduce the finished product, and 
then add the required amount of water before the condensed milk 
is cooled. It is advisable to use destilled water for this purpose. 
Ratio of Concentration.—The ratio of concentration varies 
largely with the fat content of the milk, although the locality 
and season of year are also influencing factors. \Whole milk is 
condensed at the ratio of about three parts of milk to one part 
of condensed milk, while the ratio of concentration for skim 
milk is about 4 to 1. The proper density varies somewhat with 
locahty and season of year. Roughly speaking, whole milk has 
reached the proper density when the Beaumé reading at 120 de- 
grees If is about 10 degrees I. and skim milk has reached about 
the proper density when the Beaumé reading at 120 degrees F. 
is about 14 deevrees [. When the ratio of concentration exceeds 
4+ to 1, there is danger of gritty condensed milk due to the pre- 
cipitation, in this concertrated product, of crystals of milk sugar 
Cooling —The plain condensed bulk milk is usually drawn 
into 40 quart milk cans, placed in cooling tanks containing re- 
volving cogwheels, as described in Chapter VI, under “Cooling 
Sweetened Condensed Milk,” and is cooled to as near the freez- 
ing point as facilities permit. 
Recently this crude and laborious method of cooling has 
been superseded in many of the larger condenseries by more 
modern ways. While the plain condensed bulk milk becomes 
tco thick and sluggish during the process of cooling to make 
possible the use of surface coolers, and internal-tube coolers, it 
ean be readily cooled in vats equipped with revolving dises, or 
in horizontal coil vats especially constructed for this purpose 
and in which the lower part of the vat is constricted and the coil 
sets very Jow in this constricted part, so as to agitate the milk 
vigorously and at the same time prevent the incorporation of air, 
by being completely submerged, or in circular vats equipped 
with a vertically suspended coil. Vhe vertical coil vat has the 
further advantage in that it eliminates from the milk, all bear- 
ings and glands and it expels, rather than incorporates, air, 
from the condensed milk. 
When cooled the condensed milk is ready for the market. 
