Chemicals are needed in a wide array of industries, with demand rising and falling along with the economy. So industry earnings and outlooks, especially from No. 1 Dow Chemical (DOW), offers a view of broad trends. This coming week Dow and six other chemical makers report quarterly results. Several specialty players are highly rated, including PolyOne (POL) and Eastman Chemical (EMN). Chemical companies are benefitting from the uptick in the