|The Secret of Everyday Things|
|by Jean Henri Fabre|
|Fascinating conversations with Uncle Paul reveal the mysteries behind the dyeing and weaving of cloth, the lighting and heating of homes, the processing involved in bringing oil, coffee, tea, spices, and other foodstuffs to the table, and the power of water in all its manifestations. Excellent as follow-on to The Story Book of Science. Ages 11-14 |
RON," said Uncle Paul, "is abundant and cheap;
furthermore, the hottest fire in our stoves and grates
cannot melt it, and it is able to withstand rather
rough usage. These qualities are highly important in
cooking-utensils, which must resist the action of fire
without risk of melting, and have every day to undergo
bangs and falls. But unfortunately this metal rusts on
the slightest provocation; contact with a few drops of
water for any length of time suffices to cover it with
ugly red spots which eat into it and finally pierce
quite through. This rapid deterioration is prevented by
"A metal is tinned by being overlaid with a thin
coating of tin, which resists rust. Now bear in mind
this important point, which I have already briefly
touched upon: rust develops only where air is present.
Also, it is promoted by various substances, such as
water, vinegar, and the juice of our vegetables and
fruits. Nearly all the dishes we prepare for the table
tend by their mere contact to rust metals capable of
rusting, and especially iron. To prevent the formation
of rust, therefore, what must we do? The answer is
plain: keep our food and the air from coming in contact
with any metal that will rust. If this contact never
occurs, rust will never form, for there will be nothing
to cause rust.
 "Our obvious course, accordingly, is to coat the
corruptible metal with one that will protect it, and
this last must fulfil two conditions: it must not be
liable to rust; or, at any rate, it must be a metal
that rusts with difficulty, since otherwise one ill
would only be exchanged for another; and it must also
be a metal from which food will contract no injurious
properties. This double requirement is met by very few
metals. There are, first, gold and silver, both too
expensive for common use; and finally there is tin.
This metal is very slow to rust, and, furthermore,
tin-rust if it ever begins to form, does not form in
any quantity and has, besides, no harmful properties.
Tin, therefore, furnishes us the metallic coating we
need for preserving our iron utensils from rust."
"Would n't it be much simpler," asked Claire, "to make
these utensils wholly of tin in the first place and so
get rid of iron altogether?"
"There is one serious objection to such a course: tin
melts easily. A saucepan of this metal would not hold
out for five minutes against the heat of a handful of
glowing charcoal. What would become of your stew in a
cooking-utensil capable of melting like wax over the
"I see now that tin by itself would never do."
"Nor would it answer for another reason: it offers too
little resistance, it bends under slight pressure, it
is knocked out of shape with a blow. We must have two
metals combined: iron to resist heat and stand rough
usage, and tin to prevent rust. If, however, the
utensil is not to go over the fire, it can in
 case of need be made of tin alone. Not very long ago,
in the country, tableware for company use was of tin.
Plates, platters, and soup tureens shone like silver on
the shelves of the dresser, and were the pride of the
housewife. Our measures for wine, oil, and vinegar are
of tin. The use of this metal in preference to any
other for utensils that are to come in contact with our
food is due to its perfect harmlessness. Tin keeps its
cleanness and polish and —a still more valuable
property—communicates nothing injurious to the
substances it touches.
"You are familiar with those wandering tinkers with
sooty faces who, a kettle over the shoulder and a few
old forks in one hand, go through the street, crying
their trade in a shrill voice. In the open air, over a
little charcoal fire, they restore rusty covers to
their first brilliance, mend kettles and saucepans, and
plate with tin utensils of iron and copper, to keep
them from rusting. The operation is very simple: the
piece to be tinned is first well scoured with fine
sand, and then heated over the fire, and while it is
still warm a little melted tin is rubbed over the
surface with a wad of tow. The tin takes fast hold of
the underlying metal and covers it with a thin layer
which will not come off with rubbing. That is what is
known as tin-plating."
"Then what we commonly called tin," said Marie, "is
really iron covered over with tin?"
"Yes, it is tin-plated iron, and is made by plunging
thin sheets of iron into melted tin. These tinned
sheets, light and strong at the same time, polished and
rust-proof, serve for the manufacture of
num-  berless utensils. The outfit of our kitchens consists
in great part of tinware."
"But it consists also of copper-ware," remarked Jules.
"Yes; but copper has very dangerous properties which
call for the utmost caution on our part. Iron-rust is
harmless, I might even say healthful, in limited
quantities. Little children deficient in bodily vigor
are sometimes made to drink water impregnated with a
small quantity of rust from a few old nails in the
bottom of the water-bottle. Nothing, then, is to be
feared, so far as our health is concerned, from the
rusting of iron; it is coated with tin, not as a
safeguard against danger, but to give the metal
cleanliness and greater durability.
"Copper-rust, on the contrary, is a violent poison.
This rust, or verdigris, is all the more dangerous in
that it develops with extreme ease when copper comes in
contact with our articles of food, especially when the
latter contain vinegar or fat. Have you ever noticed
the greenish tinge imparted to the oil in lamps and to
the candle-drippings on candlesticks? Well, this tinge
comes from the copper that enters into the metal part
of lamps and candlesticks, and is due to the verdigris
dissolved in the oily matter. Our food, containing as
it almost always does some slight proportion of fat or
oil, contracts the same greenish tinge by remaining any
length of time in contact with copper. Vinegar acquires
it in a few moments. This green substance from copper,
always bear in mind, is a terrible poison which cannot
be too carefully shunned. The only safe course lies
 in constant watchfulness and in a scrupulous
cleanliness that keeps all copper utensils always
bright and free from the slightest indication of a
green speck. For greater safety it is even preferable
to use only tinned ware for culinary purposes. Proof
against rust under its coating of tin, copper then
ceases to be injurious, but only on condition that the
tin coating is maintained intact, never uncovering a
particle of the poisonous metal. As soon as the tin
becomes dim and shows a little of the red underneath,
the utensil should be retinned.
"Lead is no less dangerous than copper, but this metal
enters very little into domestic use, unless it be for
cleaning bottles. A handful of small shot shaken up in
water serves excellently to remove by friction the
impurities clouding the inside of the glass. This
practice, however, is not free from one grave danger.
Suppose a few particles of lead are retained in the
bottom of the bottle and left there unobserved. Wine,
vinegar, or whatever other liquid is afterward poured
in, is likely to cause the lead to rust, and will thus
contract properties highly injurious to health. Without
any one's suspecting it there will lurk in the bottom
of the bottle that is daily used a permanent source of
poison. You see therefore what care should be exercised
in order that not a particle of lead may be left behind
after this metal has been used for cleaning purposes.
Never forget that copper and lead are two poisonous
metals, and that any carelessness in their domestic use
may suffice to imperil our very lives."
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