MILK-PLANT OPERATION. ZO 
the inspector at the bottle washer was reduced a similar amount. In 
this way the men took a special interest to prevent bottles from 
passing without careful inspection. 
As it is very important that the bottles be thoroughly cool before 
the milk is put into them, and as they must be kept clean while cool- 
ing, a separate room for storing clean bottles should be provided in 
the plant, unless there is a bottle-cooling arrangement between the 
bottle washer and the fillers. 7 
WASHING CANS. 
The matter of washing cans, while only a small part of the daily 
operations, is a very important one. Many different methods are 
used at various plants in caring for the cans after the milk is removed 
from them. There are a number of different types of cleaning 
machines on the market. The aim of the efficient ones, however, is 
thorough cleansing with washing powder and water, followed by 
rinsing, sterilization with steam, and rapid drying. After this the 
can should be covered and kept from contamination. Some of the 
largest machines are fitted with powerful pumps, and as the cans in 
an inverted position are run through the machine, sprays of washing 
powder and water, rinse water, hot water, and steam successively are 
forced into them under considerable pressure. They are then dried 
in the same* machine by a blast of hot air. 
Very satisfactory results can be obtained at small plants by washing 
the" cans thoroughly with a hand brush and water to which washing 
powder has been added. The cans should then be rinsed and steamed 
with a jet of live steam for at least 45 seconds. After steaming, the 
cans should be allowed to stand for a few seconds until thoroughly 
dry. Covers should then be placed on them. It is important that 
the cans be well dried, and if they are subjected to sufficient steaming 
they will become dry in a few seconds. Not only does drying leave 
the can in a better condition as to cleanliness, but it tends to prevent 
rust and prolong the life of the can. The cover should be thoroughly 
washed and steamed before being returned to the can. 
SANITATION IN CITY MILK PLANTS. 
The importance of cleanliness in the handling of milk can not be 
overestimated. In order to put out a high quality of milk, both 
cleanliness and care in handling are required. On arrival at the 
plant, the milk should either be put in a cold place or immediately 
started on its course through the plant. The cans of milk may either 
be put into the refrigerator or have ice packed around them, or the 
milk may be stored in tanks provided for the purpose. These tanks 
should be in a cold room or insulated with a jacket, so that the milk 
may be kept at a low temperature until it is put through the plant. 
The milk should be strained or put through a clarifier or a filter which 
removes the greater portion of insoluble dirt in the milk. At small 
plants satisfactory results can be obtained from the use of a simple 
strainer or filter of cheesecloth and cotton. Some sort of rack or 
holder is necessary to support the filter; the cheesecloth is first laid 
on one of these holders and then some sterilized cotton is placed on 
7 See U. S. Department of Agriculture -Bulletin No. 849, "City Milk Plant?— Construction and 
Arrangement." 
