II2 
NATURE 
[Fune 3, 1886 
by suitable treatment may be made to yield oils of a yaluable 
character. Of these treatments, that followed out in the process of 
gas-making is the most important, for in addition to illuminating 
gas in abundant supply, tar is produced which contains princi- 
pally that benzenoid class of substances already referred to, and 
which, to use the words of Hofmann, ‘‘ is one of the most won- 
derful productions in the whole range of chemistry.” The produc- 
tion of these latter as distinguished from the paraffinoid group 
appears to depend upon a high temperature being employed to 
effect the necessary decomposition. 
The quantity of coal made into coke for use in the blast fur- 
nace is larger than that distilled for gas-making, no less than 
between eleven and twelve million tons of coal being annually 
consumed in the blast furnaces of this country in the form of 
coke, and capable of yielding two million tons of volatile pro- 
TABLE I.—One Ton of Lancashire Coal yields 
ducts. Up to recent times, however, the whole of these volatile 
products has been burnt and lost in the coke ovens. But lately, 
various processes have been devised for preventing this loss, and 
for obtaining the oils, which might be made available as colour- 
producing materials. It is, moreover, a somewhat remarkable 
fact that only in one or two cases have the conditions been com- 
plied with which render it possible to obtain the necessary ben- 
zenoid substances. In the ordinary coking ovens, as well as in 
the blast furnaces, although the temperature ultimately reached 
is far in excess of that needed to form the colour-giving hydro- 
carbons, yet the heating process is carried on so gradually that 
the volatile products from the coal are obtained in the form of 
paraffinoid bodies mainly, and hence are useless for colour-making 
purposes. Amongst the few coking processes in which the heat 
is suddenly applied, and consequently a yield of colour-giving 
when distilled in Gas Retorts on an Average 
Ammoniacal Liquor, 
Gas (cubie feet). 
as (cub et) 5° Tw. 
10,000 | 20 to 25 gallons. 
Equal to 
Ammonium Sulphate. 
30 Ibs. 
Coal (Gas) Tar, 
sp. gr. 1°16. 
Coke. 
12 gallons=139°2 lbs. 13 hundredweights. 
Tzselve Gallons of Gas-Tar yield (Average of Manchester and Salford Tar) 
Solvent Naphtha | 
Benzene Coluene. Phenol for India-rubber, | Heavy Naphthalene. Creosote., Heavy | Anthracene. | Pitch. 
proper. containing the /Naphtha Oil. 
three Xylenes. | 
Ib. Ib. Ib. Ib. Ib. Ib Ib. Ib. Ib. 7} ate 
1710 0°90 I'5 2°44 2°40 | 6°30 17'0 14 0.46 | 69.6 
= Aniline Yoluidine yielding = a Naphthylamine 
110 o'77 o0'12 Xylene= | | 12 
Fey 0°07 Xylidine | = a or B Naphthol 
= Magenta 0°623 Aurin 4°75 { Alizarin 
I°2 = Vermilline Scarlet, RRR 20 %. 
or 1°10 Ib. Aniline 711 or 2°25. 
yields 1°23 Ib. = Naphthol Yellow? 
Methyl Violet. 9°50 
Dyeing Power of Colours from 1 Ton of Lancashire Coal. 
Ib. Ib. imal Ib. | Ib. Ib. 
0°623 Magenta or 1°23 Methyl Violet 9°50 Naphthol Yellow or 7‘11 Vermilline | 1-2 Aurin 2°25 Alizarin 20 % 
dye dye dye dye | dye dye 
509 yards 27 in. wide 1000 yards 27:in. wide 3800 yards 27 in. wide 2560 yards 27 in. wide'120 yards 27 in. wide 255 yds. Printer’s cloth 
Flannel a full shade. Flannel a full Violet.|Flannel a full Yellow. Flannel a full Scarlet.'Flannel a full Orange. a full Turkey Red. 
Dyeing Power of Colours from 1 1b. of Lancashire Coal. 
| 
Magenta or 
a piece of Flannel 
8 in. by 27 in. 
Violet 
a piece of Flannel 
24 in. by 27 in. 
a piece of Flannel 
61 in. by 27 in. 
Yellow or 
Scarlet | 
a piece of Flannel 
4l in. by 27 in. | 
Orange 
a piece of Flannel 
1°93 in. by 27 in. 
Turkey Red 
a piece of Flannel 
4 in. by 27 in. 
1 The Naphthol Yellow is a representative colour from a Naphthol, while the Vermilline Scarlet is a representative colour from the combination of 
1 Naphthylamine with # Naphthol. 
hydrocarbons is obtained, may be mentioned the patented pro- 
cess of Simon-Carvés, the use of which is now spreading in 
England and abroad. The tar obtained in this process is almost 
identical in composition with the average gas-works tar, whilst 
the coke also appears to be equal for iron-smelting purposes to 
that derived from other coke ovens. A third source of these oils 
yet remains to be mentioned, viz. those obtained as a by-product 
in blast furnaces fed with coal. 
; Another condition has, in addition, to be considered in this 
industry, and that is the nature of the coal employed for distilla- 
tion, It is a well-known fact that if Lancashire cannel be 
exclusively employed in gas-making a highly-luminous gas is | 
obtained, but the tar is too rich in paraffins to be a source of | 
profit to the tar-distiller, whilst, on the other hand, coal of a more | 
anthracitic character, like that from Newcastle or Staffordshire, 
, yields a tar too rich in one constituent, viz. naphthalene, and 
too poor in another, viz. benzene. It is also known to those 
engaged in carbonising coal principally for the sake of the tar that 
the coal from different measures, even in the same pit, yields tars 
of very different constitution. That under these varying condi- 
tions products of varying composition are obtained is a result 
that will surprise no one who considers the complicated chemical 
changes brought about in the process of the destructive distillation 
of coal. 
flistory of Benzene and tts Derivatives.—Having thus sketched 
the principles upon which the formation of these valuable tar 
colours depends, we should do wrong to pass over the history of 
the discovery of benzene (C,H,), which contributed so much to 
the unlocking of the coal-tar treasury. 
Faraday in 1825 discovered two new hydrocarbons in the oils 
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