ht
pressure within the jar. This we call a "blow-out."

Rubber rings should be capable of withstanding four hours of
sterilization in boiling water without blowing out on partially sealed
jars, or one hour under ten pounds of steam pressure. They should be
selected with reference to proper inside diameter, width of flange,
and thickness. Good rubber will stretch considerably and return
promptly to place without changing the inside diameter. They should
also be reasonably firm and able to stand without breakage. Color is
given to rings by adding coloring matter during the manufacturing
process. The color of the ring is no index to its usefulness in home
canning. Red, white, black or gray may be used.

Always use _new_ can-rubbers with each year's product of canned goods.
An old rubber may look like a new one but it has lost its elasticity
and its use may cause imperfect sealing and thus endanger the keeping
quality of the food. This is always a hard thing to impress upon
thrifty penny-saving housekeepers. The old rubber looks so good, so
why not use it? But be wise in this and remember it is _never safe to
use old rubbers_. New rubbers are expensive but what about the cost of
the product, the loss of your time and fuel! One jar lost due to an
old rubber is so much food, time and fuel lost.

And do not think yourself thrifty to use two old rubber rings instead
of one, thereby thinking to obtain a better seal, for you will not.
Two old rubbers are inferior in strength to one new good rubber. If
you use old rubbers and your canned goods spoil, blame the rubbers.

GLASS JARS

Next in importance to the rubbers are the glass jars you use. There
are many kinds of fruit jars on the market. The question is frequently
asked, "Which jars on the market are the best." The only answer to
that is to choose the jar which is simplest in construction, which
will seal perfectly and wash easily, which protects the contained food
against contact with metal, which has the fewest parts to lose or
misplace and which fits the shelves and receptacles planned to hold
it.

FLAT SOUR

Flat-sour often causes annoyance to beginners in canning some
vegetables, such as corn, peas, beans and asparagus. These canned
foods may show no signs of spoilage and yet when the can is opened the
product may have a sour taste and a disagreeable odor. This
"flat-sour" is not harmful and must not be confused with "botulinus,"
which is harmful. However, t