ber
composition; the uppers of cellulose fabric (canvas) coated with a
cellulose solution such as I have described.

Each firm keeps its own process for such substance a dead secret, but
without prying into these we can learn enough to satisfy our legitimate
curiosity. The first of the artificial fabrics was the old-fashioned and
still indispensable oil-cloth, that is canvas painted or printed with
linseed oil carrying the desired pigments. Linseed oil belongs to the
class of compounds that the chemist calls "unsaturated" and the
psychologist would call "unsatisfied." They take up oxygen from the air
and become solid, hence are called the "drying oils," although this
does not mean that they lose water, for they have not any to lose.
Later, ground cork was mixed with the linseed oil and then it went by
its Latin name, "linoleum."

The next step was to cut loose altogether from the natural oils and use
for the varnish a solution of some of the cellulose esters, usually the
nitrate (pyroxylin or guncotton), more rarely the acetate. As a solvent
the ether-alcohol mixture forming collodion was, as we have seen, the
first to be employed, but now various other solvents are in use, among
them castor oil, methyl alcohol, acetone, and the acetates of amyl or
ethyl. Some of these will be recognized as belonging to the fruit
essences that we considered in Chapter V, and doubtless most of us have
perceived an odor as of over-ripe pears, bananas or apples mysteriously
emanating from a newly lacquered radiator. With powdered bronze,
imitation gold, aluminum or something of the kind a metallic finish can
be put on any surface.

Canvas coated or impregnated with such soluble cellulose gives us new
flexible and durable fabrics that have other advantages over leather
besides being cheaper and more abundant. Without such material for
curtains and cushions the automobile business would have been sorely
hampered. It promises to provide us with a book binding that will not
crumble to powder in the course of twenty years. Linen collars may be
water-proofed and possibly Dame Fashion--being a fickle lady--may some
day relent and let us wear such sanitary and economical neckwear. For
shoes, purses, belts and the like the cellulose varnish or veneer is
usually colored and stamped to resemble the grain of any kind of
leather desired, even snake or alligator.

If instead of dissolving the cellulose nitrate and spreading it on
fabric we combine