tion of the iron with oxygen, for which it has so
great an affinity that it will decompose water to get oxygen to unite
with; hence it is that iron utensils rust so quickly when not carefully
dried after using, or if left where they can collect moisture. This is
the reason why a coating of tallow, which serves to exclude the air and
moisture, will preserve ironware not in daily use from rusting.

"Porcelain ware" is iron lined with a hard, smooth enamel, and makes
safe and very desirable cooking utensils. German porcelain ware is
unexcelled for culinary purposes.

"Granite ware" is a material quite recently come into use, the
composition of which is a secret, although pronounced by eminent
chemists to be free from all injurious qualities. Utensils made from it
are light in weight, easily kept clean, and for most cooking purposes,
are far superior to those made from any other material.

What is termed "galvanized iron" is unsuitable for cooking utensils, it
being simply sheet iron coated with zinc, an exceedingly unsafe metal to
be used for cooking purposes.

Tin, which is simply thin sheet iron coated with tin by dipping several
times into vats of the melted metal, is largely employed in the
manufacture of cooking utensils. Tinware is acted upon by acids, and
when used for holding or cooking any acid foods, like sour milk, sour
fruits, tomatoes, etc., harmful substances are liable to be formed,
varying in quantity and harmfulness with the nature of the acid
contained in the food.

In these days of fraud and adulteration, nearly all the cheaper grades
of tinware contain a greater or less amount of lead in their
composition, which owing to its greater abundance and less price, is
used as an adulterant of tin. Lead is also used in the solder with which
the parts of tinware are united. The action of acids upon lead form very
poisonous compounds, and all lead-adulterated utensils should be wholly
discarded for cooking purposes.

_Test for Lead-Adulterated Tin._--Place upon the metal a small drop of
nitric acid, spreading it to the size of a dime, dry with gentle heat,
apply a drop of water, then add a small crystal of iodide of potash. If
lead is present, a yellowish color will be seen very soon after the
addition of the iodide. Lead glazing, which is frequently employed on
crockery and ironware in the manufacture of cooking utensils, may also
be detected in the same manner.

Cooking utensils made of copper are not t