ted out of tubes through extremely minute holes into acidulated
water, each tiny stream becomes instantly solidified into a silky thread
which may be spun and woven like that ejected from the spinneret of the
silkworm. The origin of natural silk, if we think about it, rather
detracts from the pleasure of wearing it, and if "he who needlessly
sets foot upon a worm" is to be avoided as a friend we must hope that
the advance of the artificial silk industry will be rapid enough to
relieve us of the necessity of boiling thousands of baby worms in their
cradles whenever we want silk stockings.

On a plain rush hurdle a silkworm lay
When a proud young princess came that way.
The haughty daughter of a lordly king
Threw a sidelong glance at the humble thing,
Little thinking she walked in pride
In the winding sheet where the silkworm died.

But so far we have not reached a stage where we can altogether dispense
with the services of the silkworm. The viscose threads made by the
process look as well as silk, but they are not so strong, especially
when wet.

Besides the viscose method there are several other methods of getting
cellulose into solution so that artificial fibers may be made from it. A
strong solution of zinc chloride will serve and this process used to be
employed for making the threads to be charred into carbon filaments for
incandescent bulbs. Cellulose is also soluble in an ammoniacal solution
of copper hydroxide. The liquid thus formed is squirted through a fine
nozzle into a precipitating solution of caustic soda and glucose, which
brings back the cellulose to its original form.

In the chapter on explosives I explained how cellulose treated with
nitric acid in the presence of sulfuric acid was nitrated. The cellulose
molecule having three hydroxyl (--OH) groups, can take up one, two or
three nitrate groups (--ONO_{2}). The higher nitrates are known as
guncotton and form the basis of modern dynamite and smokeless powder.
The lower nitrates, known as pyroxylin, are less explosive, although
still very inflammable. All these nitrates are, like the original
cellulose, insoluble in water, but unlike the original cellulose,
soluble in a mixture of ether and alcohol. The solution is called
collodion and is now in common use to spread a new skin over a wound.
The great war might be traced back to Nobel's cut finger. Alfred Nobel
was a Swedish chemist--and a pacifist. One day while working in the
laborato