Naphthas

The most important of these are benzene, toluene, and the three isomers of xylene. Amount 1-5 per cent.

Light Oils

Containing aromatic hydrocarbons, phenol, cresol and other homologues of phenol. Amount 5-10 per cent.

Creosote Oil

Containing also high aromatic hydrocarbons, high phenol homologues and naphthalene. Amount 15-25 per cent.

Yellow Oil

Containing still higher aromatic hydrocarbons and anthracenes. Amount 5-10 per cent.

Pitch

Amount 50-65 per cent.

The Tar Industry

The magnitude of the tar-distilling industry in this country can be judged by reference to the following figures, showing the amounts of tar produced and distilled. It seems impossible to obtain complete statistics of any pre-war period, as reliable data were not then kept, and figures relating to these periods can only be estimated roughly. From the Annual Reports on alkali and other works, by the Chief Inspector, are obtained the following data :-

Tar distilled in

1916.

1917.

1918.

1919.

Gas and Coke Oven Works }

1,420,867

1,526,209

1,510,065

1,402,987

Other Works

138,552

126,966

131,325

106,056

Total in Tons.

1,559,419

1,653,175

1,641,390

1,509,043

From the Reports for 1916 and 1917 it would appear as though the tar had been obtained from gas works only, but there is no doubt that the figures given should refer to both kinds of works. The Ministry of Munitions collated complete returns of tar produced and distilled during the war and have kindly given the writer the following summaries: Coal Tar and Coke Ovens Tar Distilled, in Tons

1913.........

1,320,000

1914

1915 }Average.....................................................

1916;

1,376,397

1917........................................................................

1,574,863

Sept. 1917 to Aug. 1918.....

1,417,919

„ ,, (actual production) ................

1,523,401

For the years prior to Sept. 1917 the total production of tar may be taken as approximately 100,000 tons annually more than that shown as distilled.

For the year Sept. 1917 to Aug. 1918 the sources of tar produced were: -

Gas Works and Produce Plants.................

949,397

Coke Ovens............................

...........................

558,561

Water-gas Plants..............

...........................

15,443

Total....................

1,523,401

Against these figures estimates of the tar produced have been made, and Dr. Beilby, in an address to the Society of Chemical Industry, 1900, gives such an estimate for the year 1899 as follows: Tar Produced, in Tons

Gas Works............

.....................................

650,000

Blast Furnaces.............

..............................

150,000

Coke Oven.....................

...........................

62,000

An interesting estimate of the tar produced by all countries of the world for the year 1901 appears in Chemical Discovery and Invention in the Twentieth Century, by Tilden (p. 305) as follows: -

Tons.

United Kingdom ......

. 908,000

Germany . . . . . . . . . .. . . . . . .. . . . . . .

. 590,000

United States (including water-gas tar). . . . . . . . . . . .

. 272,400

France . . . . . . . . . . . . . . . . . . . . .

. 190,680

Belgium, Holland, Sweden, Norway, and Denmark . . . . .

. 272,400

Austria, Russia, Spain, and other European countries . . . .

. 199,760

All other countries......

. 227,000

Total

2,660,240

From this it is evident that the industry in the United Kingdom is more important than in any other country in the world, and, comparing the total of these figures with the tar produced during the most important period of the war, one sees that the United Kingdom produced then very nearly as much as the rest of the world at the beginning of the twentieth century.