[SOMETHING ABOUT COAL-TAR.]
BY B. SHIPPEN, M. D.
Most people know and dislike the odor of coal-tar, which is distilled from soft or bituminous coal in making gas, as well as in other processes.
It seems to have been first collected by a German, named Stauf, in 1741. Of course there was no question of gas-making then, and the German, who was more of an alchemist than a chemist, was looking for other things than the coal-oil which he obtained.
The coarse oil which Stauf procured had little in it to his eye, but it contained, nevertheless, many bright and varied colors, delicate perfumes, useful medicines and the sweetest product ever known to man.
From coal-tar is derived benzine and naphtha, and colors—especially purples—which are used in dyeing. From one ton of good cannel coal, distilled in gas retorts, there comes ten thousand cubic feet of gas, twenty-five gallons of ammoniacal liquor, thirty pounds of sulphate of ammonium, thirteen hundred weight of coke and twelve gallons of coal-tar.
From this tar are produced a pound of benzine, a pound of toluene, a pound and a half of phenol, six pounds of naphthalene, a small quantity of a material called xylene and half a pound of anthracene, which is used in dyeing.