American Milk-Condensin(/ Factories. 131 
has been partially condensed. The sugared milk must be de- 
prived of more water than the plain milk, since the addition 
Fig. 8. — Heating-Well, loilh Jacketed 
Bottom for Steam, used at Borden's 
Factory. 
of sugar partially liquefies the mass — a curious fact. Three 
pints of milk make a pound of sugared milk. The three pints 
of raw milk will weigh on an average 3 lbs. 3^ ozs. Now, 
by abstracting 75 per cent, of water (38 iVo"o ozs.), we have 
remaining 12 ozs. and of an ounce ; add to this the proportion 
of sugar now used, 6f oz., or about S-^ ozs. more than a pound, 
and it will be seen this 3-j^ ozs. of water have to be removed 
in addition to the 75 per cent, of water in the first instance. 
Mr. Borden told me that the matter of getting the right propor- 
tion of sugar was the result of long study and numerous experi- 
ments, and no other proportions gave such good results in the 
product. 
The plain condensed milk is reduced from 4 to 1. It is 
treated in the pan precisely like the other, except near the close 
of the operation, when the vacuum in the pan is broken, and the 
mass superheated, or raised to a temperature of 190^ to 200°. 
The superheating process was discovered in 1862, and this is 
one reason which gives the Borden brands their superiority in 
the market. The superheating not only helps the keeping quali- 
ties, but prevents granulation. 
During the superheating process, the water which passes off 
lias an intensely disagreeable odour. The heat in the vacuum- 
j)an throughout the whole of the Borden process, apart from 
K 2 
