<P> In textiles and dyeing, salt is used as a brine rinse to separate organic contaminants, to promote "salting out" of dyestuff precipitates, and to blend with concentrated dyes to standardize them . One of its main roles is to provide the positive ion charge to promote the absorption of negatively charged ions of dyes . </P> <P> It is also used in processing aluminium, beryllium, copper, steel and vanadium . In the pulp and paper industry, salt is used to bleach wood pulp . It also is used to make sodium chlorate, which is added along with sulfuric acid and water to manufacture chlorine dioxide, an excellent oxygen - based bleaching chemical . The chlorine dioxide process, which originated in Germany after World War I, is becoming more popular because of environmental pressures to reduce or eliminate chlorinated bleaching compounds . In tanning and leather treatment, salt is added to animal hides to inhibit microbial activity on the underside of the hides and to attract moisture back into the hides . </P> <P> In rubber manufacture, salt is used to make buna, neoprene and white rubber types . Salt brine and sulfuric acid are used to coagulate an emulsified latex made from chlorinated butadiene . </P> <P> Salt also is added to secure the soil and to provide firmness to the foundation on which highways are built . The salt acts to minimize the effects of shifting caused in the subsurface by changes in humidity and traffic load . </P>

Why does common table salt (naci) have a high melting point