18 
this chapter, milk is very variable as to its coagulability. It 
depends largely on the acidity of the milk which in turn de- 
pends largely on the good care of the fresh milk, on the 
thorough cleanliness of all apparatus, pipes, etc. But, as 
pointed out, it depends also on many other factors less known 
and less controllable. The higher the condensation the less 
heat alsc will be required to thicken the milk. Generally 
speaking, the milk is heated to about 220 to 240 degrees F. 
for from 20 to 40 min. The exact mode of application differs 
considerably for different firms, and is usually kept strictly se- 
erect. Constant experimenting, close watching and sampling 
ahead is indispensable. According to season the ratio of con- 
densation has also to be varied to make the milk sterilizable* 
When ir the sterilizing process the desired heat and time is 
reached, the milk is immediately cooled by shutting off the 
steam and running cold water into the sterilizer while frame- 
work is still in revolution. The process has been made somewhat 
more secure since the introduction of the homogenizing ma- 
chine. This is a device to break up the fat globules in the 
milk into smaller particles so that on account of the higher 
surface tension they remain suspended, i.e., the fat does not 
rise to the top. The milk is run through the homogenizer di- 
rectly as it comes from the condensing pan. 
After sterilization the milk is placed in a heated store- 
room for about a month and during that time turned over in 
the trays several times. Milk in cans that are not absolutely 
air-tight, on account of faulty soldering, will decompose mostly 
under gas production so that they show up as “bloats” or 
“swell neads.” Other faulty milk is easily detected by an 
experienced tester by the sound in shaking the cans. In every 
batch a few samples are taken also from the good cans hefore 
they go to the storeroom and before they are shipped out, in. 
order to inspect the milk for its general condition as to butter 
fat separation, grainyness, colour, etc. Exact records are kept 
*From this it also follows that hard and fast rules in regard to 
standards cannot always be followed. .The manufacturer is bound by 
exigencies of the process to a large extent. The relation of fat and other 
solids in milk varies with the seasons, and with other factors, as does also 
the behaviour as to coagulation. Manufacturers have been put to 
considerable inconveniences by the prescribing of government standards 
without expert knowledge, and with which it was at times impossible to 
comply. This condition has been more or less remedied of late. 
