What does "berlin" mean?

Berlin: Fine worsted for fancy-work; zephyr worsted; -- called also Berlin wool. Berlin black, a black varnish, drying with almost a dead surface; -- used for coating the better kinds of ironware. Ure. -- Berlin blue, Prussian blue. Ure. -- Berlin green, a complex cyanide of iron, used as a green dye, and similar to Prussian blue. -- Berlin iron, a very fusible variety of cast iron, from which figures and other delicate articles are manufactured. These are often stained or lacquered in imitation of bronze. -- Berlin shop, a shop for the sale of worsted embroidery and the materials for such work. -- Berlin work, worsted embroidery.