Paper marbling Turkish and Persian, which literally means Frankish. Historic forms of marbling used both organic and inorganic pigments mixed with water for colors, and sizes were traditionally made from gum tragacanth ("Astragalus" spp.), gum karaya, guar gum, fenugreek ("Trigonella foenum-graecum"), fleabane, linseed, and psyllium. Since the late 19th century, a boiled extract of the carrageenan-rich alga known as Irish moss ("Chondrus crispus"), has been employed for sizing. Today, many marblers use powdered carrageenan extracted from various seaweeds. Another plant-derived mucilage is made from sodium alginate. In recent years, a synthetic size made from hydroxypropyl methylcellulose, a common ingredient in instant wallpaper
Simultaneously extracted metals and Acid-volatile sulfide Simultaneously extracted metals and Acid-volatile sulfide Simultaneously extracted metals/Acid-volatile sulfide (SEM-AVS) is an approach used in the field of aquatic toxicology to assess the potential for metal ions found in sediment to cause toxic effects in organisms dwelling in the sediment. In this approach, the amounts of several heavy metals in a sediment sample are measured in a laboratory; at the same time, the amount of acid-volatile sulfide (sulfide which can be liberated from the sediment by treatment with hydrochloric acid) is determined. Based on the chemical interactions between heavy metals (SEM) and acid-volatile sulfide (AVS), the concentrations of these