SWEETENED CONDENSED Mu,.K—CONDENSING 
rapidity of evaporation only as long as enough water passes 
through the condenser to maintain a high vacuum. As soon as 
the steam pressure in the jacket and coils reaches the point where 
the water in the condenser fails to promptly reduce the vapors, 
the vacuum drops, the temperature in the pan rises and evapora- 
tion is checked. - 
The condensing of milk requires immense quantities of water; 
experience has shown that it takes from one to three gallons of 
water to condense one pound of fresh milk, the exact amount 
depending on the construction of the condenser and the tempera- 
ture of the water. ‘The water supply is one of the weakest links 
in most condenseries, so that economy of water is one 
of the important factors to be considered. The steam pressure 
in the jacket and coils should, therefore, be so regulated as to 
make it possible to maintain the maximum vacuum consistent 
with reasonably economic use of water. With a vacuum of 
twenty-five inches the temperature in the pan is about 135 de- 
grees F., the temperature varving somewhat with the altitude 
of the factory. In some condenseries the temperature of the pan 
is kept at 150 degrees F. This practice may economize the water 
a trifle better, but the rapidity of evaporation is considerably 
lower. 
Condensing at temperatures lower than 130 degrees F., with- 
out reducing the steam pressure in the jacket and coils, increases 
the rapidity of evaporation, but taxes the water supply beyond 
the reach of most condenseries. So much water has to be used 
in the condenser that it is not used economically, as is shown by 
the relatively low temperature of the water discharging from the 
condenser. The temperature of the condenser discharge bears 
a direct relation to the temperature of the vapors in the pan, 
Observations made in various factories and under different con- 
ditions by Hunziker and others showed that the condenser dis- 
charge was anywhere from 5 to 25 degrees F. lower in tempera- 
ture than the vapors in the pan, the difference averaging about 
15 degrees F. 
The smaller the difference in temperature between the con- 
denser discharge and the vapors in the pan, the more economic 
is the use of the water and vice versa. It is not advisable under 
