produced by the chemical breakdown of wood strips by means of sulphurous acid, for use in such applications as absorbent material in surgical dressings. Another application of this product was use in sanitary towels, as shown in advertisements from 1885–1892 in Britain for "wood wool diapers" or "sanitary wood wool sheets". European "wood wool" was known in America in the late nineteenth century as being distinctly different from excelsior. The wood wool that is the topic of this article is what has traditionally been known as excelsior in the United States. Fifteen US patents related to "slivering machines" for producing the small wood shreds "known as excelsior" were listed by 1876. The earliest, a machine for "Manufacturing wood to be used as a substitute for curled hair in stuffing beds" was patented in the US in 1842; however, the product had no specific name when the process was first patented. The 1868 patent, "Improved capillary material for filling gas and air carburettors," was for a new use for "fibres torn from the wood by suitable machinery" to be "sold and used as filling for mattresses, its commercial name being 'excelsior'." This is the earliest description of the material by this name cited by the Oxford English Dictionary, though the term "excelsior mattress" had appeared in print as early as 1856. In 1906, the now-common use of excelsior in the cooling pads of evaporative coolers appeared in a patent that stated, "I have found that excelsior makes a very cheap and good material for this purpose." In the beginning of the 20th century wood wool was used as a raw material for producing wood wool panels in Europe, especially in Austria. By 1930, wood wool cement boards were being widely produced. In the 21st century, excelsior appears in numerous patents for erosion control and sediment control methods and devices; for example, the 2006 "Sediment control device and system." A few late-twentieth-century patents on these uses refer to "excelsior/wood wool." References Biodegradable materials Fibers Wood products