Griggs courier., 1888-08-31
HOW GAS is MADE.
An Explanation of the Details Which Co
plicate the Really Simple Process.


An Explanation of the Details Which Conn
plicate the Really Simple Process.
The principle of gas manufacture i,
very Simple, but there are many prac-
tical details which complicate the actual
process. 1t depends upon the fact that
when bituminous coal containing car
bon and hydrogen is subjected to heat
in a retort, it is partially decomposed.
giving off gaseous hydrocarbons and
other products, and leaving behind a
mass of carbon commonly known as
coke. But many other compounds are
formed at the same time, which must
be separated from the gas before it is
fit to be sent into the pipes. and deliv-
cred to the consumer. The products
of the distillation OF coal may be divi-
ded roughly into four classes-coke.
coal-tar, ammoniacal liquor and illum-
mating gas. Coke contains from ninety
to ninety-tive per cent. of pure carbon.
the remainder being ash and sulphide
OF iron. The ammoniacal liquor con-
tains at least five different salts of am
monia. The coal-tar contains about
forty different liquid and solid hydro
carbons, and the illuminating gas twen-
ty-tive or more gaseous hydrocarbons
IA total of over seventy distinct
chemical substances, all produced
blythe distillation of apiece of soft coal.
1t must be remembered that few or
none Of these exist by themselves in
the coal. but are all formed by the
chemical reactions which take place
during the distillation. The retorts
in which the coal is distilled are
made either of cast-iron or tire-clay;
they are about nine feet long and
one and a half feet in diameter
After being filled with coal, they are
raised to Il red heat, or even higher
The impure gas thus formed passes off
through an upright pipe, which con-
meets with a horizontal one partly
filled with water. known rs the hydrau-
lie main. The pipe from the retort dips
under the water, so that all the gas
must pass through it. The coarser and
large proportion of the tar, are con-
densed in this main. The gas, however.
is still at a high temperature, and very
impure; so it is sent through set Of
vertical pipes connected with each
other like a steam radiator, which are
either exposed to the air. or cooled
artificially. Many of the impurities
are condensed and separated from the
gas in the cooler. but it is sometimes
still further purified by being passed
through large iron vessels filled with
Jumps of coke over which stream of
cold water is constantly flowing. This
still further purities the gas. especially
by absorbing the ammoniacal com
pounds; but the offensive and danger
Gus sulphur compounds remain, and to
remove these the gas is sent through
large iron boxes containing movable
trays covered with moist. freshly
Stacked lime. The lime absorbs the
greater part of the compounds of sui
ph,n'. and the gas is then ready
to be stored in the large holders.
improperly called gasometers, and
from thence delivered to the GUS
toner. After absorbing the i'm
purities the gas-lime. as it called
possesses a most horrible odor. and in
thickly settled localities its disposal
without creating Il nuisance is an i'm
portant and sometimes difficult mat
ter A more effective and simpler
means of purifying gas is much to be
desired. What is known as water-gas
has been substituted to some extent for
that distilled from coal. 1t is essen
TALLY q mixture Of hydrogen and car
bonis oxide. and is formed by curious
reaction which takes place when steam
is passed over red-hot Goals The steam
is deccmpossd, and hydrogen is set
free. while the oxygen unites with the
carbon Of the coal to form carbonic
oxide (CC). AS this gas burns with Il
non-luminous flame. it must be '.en-
riched' with light-giving hydrocar-
bons, which are usually obtained from
the Installations of crude petroleum. 1t
is claimed that this gas is much cheaper
than that produced by the old process:
but practical trials have not as yet con-
tirmed this, and the presence of the
highly poisonous carbonic oxide rem
ders it much more dangerous agent
to introduce into dwellings.
Science NcWS.
"A German authority attaches some
Importance to troublesome silk spin
ner Of India" -"Gricula trifenestrata''
from which an excellent fiber has
been obtained. This silk worm is tx,
traordinarily productive, the living be-
Ing surviving two generations in one
year, and it forms new and remarka-
BILE source of raw material for the silk