Salt-contamination, mortar

Europeans—dyed their hair red with soap. (The soap may have just taken dirt off a naturally red-headed people). And Pliny did strive to be comprehensive. He recorded processes involving metals, salts, sulfur, glass, mortar, soot, ash, and a large variety of chalks, earths, and stones. He describes the manufacture of charcoal the enrichment of the soil with lime, ashes, and manure the production of wines and vinegar varieties of mineral waters plants of medical or chemical interest and types of marble, gems and precious stones. He discusses some simple chemical reactions, such as the preparation of lead and copper sulfate, the use of salt to form silver chloride, and a crude indicator paper in the form of papyrus strips soaked in an extract of oak galls that changed color when dipped in solutions of blue vitriol (copper sulfate) contaminated with iron. 

Salt, B. et al.. Recycling contaminated spent blasting abrasives in portland cement mortars using solidification/stabilization technology, Report CTR 0-1315-3F, U.S. Department of Commerce, National Technical Information Service (NTIS), Spring-field, 1995. 

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