The midland journal., 1915-11-12
MAGIC COAL TAR.
Once Despised, II Is Now a Source
of LimitIess Products.
SPANS THE WORLD OF COLOR.

ana Is OSeu IN FracticaIlI Every In-
dustry-in Medicine and Surgery,
Also, It Has Worked Wonders.
Among the almost limitless number
of natural products Of this country
coal tar stands well in the lead in the
variety of uses to which it may be ap-
piled. Evil smelling, it is the rough
material from which many valuable
substances have been obtained after
years of persistence by science and In
dustry.
These substances include wide
range Of colors, various burning and
lubricating oils, asphalt for pavements,
Photographic developers and great
number of medicines, flavors and per-
fumes. Coal tar is used In practically
every manufacturing process where
dyes are needed, in making cloths,
silks, dress materials, colored papers
and even colored articles of food.
About a century ago coal tar was
considered almost waste product, and
no one had thought it worth while to
experiment with it. At that time gas
was being introduced as a new light,
and Frederick Accum, who wrote one
of the first books on gas lighting. sug-
gested the boiling of the tar in still
and the condensation and collection Of
the volatile products. The experiment
was made, and the process yielded two
oils. One was heavy and the other
light. 1t was soon found that the
heavy could be satisfactorily used as
preservative for wood that had to be
fixed underground or submerged in
water and was used extensively in pre-
serving piers and wharfs.
Further experiments with the lighter
oil were made by Scotch chemist,
Macintosh, who used 1t in waterproof
ing the clothing which still bears his
name. 1t also Is used as solvent in
varnish making and as coal naphtha
for lighting. Experiments with naph-
tina disclosed rich treasury of colors
which for centuries had been locked up
in coal and its refuse-tar BenZine
was extracted from naphtha and this
in turn produced the different shades
Of violet, green, blue and yellow. Later
another chemist made the commercial
manufacture Of benzine possible. He
was experimenting on the artificial pro-
duction of qutnine, and, using base
known as aniline, obtained the coloring
matter called mauve.
This laid the foundation for the coal
| %aw 4y,d xr1h&
ed until today almost every color and
shade of color is derived from aniline.
Aniline had been obtained previously
from the indigo plant "anil.". The dis
covery of mauve created large de-
mand for the artificial aniline base
and gave unexpected value to benzine.
1t yielded aniline by being treated with
nitric acid and with the borings of cast
iron powdered into dust. Having done
its work in the aniline still, the dust
was used by the gas maker to cleanse
his coal gas from sulphur, and then it
passed to the manufacturing chemist,
who burned the sulphur out of it and
produced sulphuric acid-a cycle of op-
erations whose beginning and end was
the utilization of waste.
This method of producing color was
responsible for the desolate madder
fields of France and Holland and for
the loss to the Hindus of their long
cherished indigo cultivation. Anthra-
Gene, one of the heavier oils of coal
tar, caused the fall of the madder
growing industry. The madder pro-
duced violets, reds, blacks, purples and
dark browns. Anthracene was sold
very cheaply for lubricating purposes
until certain chemists heated it with
zinc filings and produced alizarin. and
then the secret of the madder plant
was discovered.
In this way chemistry displaced agri-
culture one pound of alizarin having
the coloring power of ninety pounds of
madden. and the lubricating oil sold at
a trif1e as waste became a valuable
colOring matter worth $500 a ton.
thereby creating IL vast industry.
In medicine and surgery coal tar has
worked wonders. Saccharin. many hun
dred times the sweetening power Of
sugar, Is used by diabetic patients.
Carbolic acid is separated from the oil
of coal tar by successive Oscillations,
and in surgical operations a spray Of
germ killing carbolic acid is used.
Quinoline, antipyrine and other fever
assuagers are made from coal tar, and
various antiseptics and food preserva-
tives also are obtained from it.
Vanilla fiavoring for cooking. which
formerly was prepared from a bean,
can now be obtained from the vanillin
of the gas works, and even this vanil-
lin can be made into a heliotrope per-
fume by adding oil of almonds. while
the latter can be produced by treating
benzine with an acid. Huge quanti-
tes of this oil are used In the making
of scented soaps. As a matter of fact
there is scarcely department of life
into which the products of coal tar do
not enter.-New York Times.