lushed with solder so
as to be easily cleaned (see Fig. 6). In much of the cheaper tin ware on
the market, the soldering of joints and seams is very imperfect,
affording a place of refuge for bacteria and dirt.

Cans are often used when they are in a condition wholly unsuitable for
sanitary handling of milk. When the tin coating becomes broken and the
can is rusty, the quality of the milk is often profoundly affected.
Olson[1] of the Wisconsin Station has shown that the action of rennet is
greatly impaired where milk comes in contact with a rusty iron surface.

[Illustration: FIG. 6.]

With the introduction of the form or hand separator a new milk utensil
has been added to those previously in use and one which is very
frequently not well cleaned. Where water is run through the machine to
rinse out the milk particles, gross bacterial contamination occurs and
the use of the machine much increases the germ content of the milk.
Every time the separator is used it should be taken apart and thoroughly
cleaned and dried before reassembling.[2]

~Use of milk-cans for transporting factory by-products.~ The general
custom of using the milk-cans to carry back to the farm the factory
by-products (skim-milk or whey) has much in it that is to be deprecated.
These by-products are generally rich in bacterial life, more especially
where the closest scrutiny is not given to the daily cleaning of the
vats and tanks. Too frequently the cans are not cleaned immediately upon
arrival at the farm, so that the conditions are favorable for rapid
fermentation. Many of the taints that bother factories are directly
traceable to such a cause. A few dirty patrons will thus seriously
infect the whole supply. The responsibility for this defect should,
however, not be laid entirely upon the shoulders of the producer. The
factory operator should see that the refuse material does not accumulate
in the waste vats from day to day and is not transformed into a more or
less putrid mass. A dirty whey tank is not an especially good object
lesson to the patron to keep his cans clean.

It is possible that abnormal fermentations or even contagious diseases
may thus be disseminated.

Suppose there appears in a dairy an infectious milk trouble, such as
bitter milk. This milk is taken to the factory and passes unnoticed into
the general milk-supply. The skim-milk from the separator is of course
infected with the germ, and if conditions favor its growth, the who