EDTA crystals, light micrograph
EDTA crystals. Polarised light micrograph of a section through ethylenediaminetetraacetic acid (EDTA) crystals. EDTA is used primarily for its effectiveness at binding metal ions (chelating). After being bound by EDTA, metal ions remain in solution but exhibit distinctly diminished reactivity. In industry it has a variety of uses, including for dissolving limescale and preventing metal ion impurities from modifying the colours of dyed products. In medicine EDTA is used to treat heavy metal poisoning through chelation therapy, where it is used to bind metal ions in the body. Magnification: x100, when printed 10 centimetres wide.
© MAREK MIS/SCIENCE PHOTO LIBRARY
Microcystis blue-green alga
Blue-green algae. Coloured transmission electron micrograph of a single cell of the blue-green algae Microcystis aeruginosa (also known as Anacystis cyanea). Blue-green algae (cyanobacteria) are primitive algae; in structure they are related to bacteria. They are prokaryotes containing no membrane-bound nucleus; instead, as in bacteria, nuclear material is dispersed throughout the cell. Photosynthetic lamellae (thread-like structures, outer part of cell) are the primitive chloroplasts. M.aeruginosa cells are found in colonies; they bloom in late summer and may liberate a toxin that kills plankton, fish and birds. Magnification: x16, 320 at 6x6cm size.
© A.B. DOWSETT/SCIENCE PHOTO LIBRARY
Victorian Wallpaper - in popular emerald green - which contained poisonous arsenic
Victorian Wallpaper - in popular emerald green - which contained poisonous arsenic. William Morris, famed for his wallpaper designs, was the son of the owner of the largest arsenic producing company in the country. He was sceptical that arsenic was bad for you and held that because he had arsenical wallpaper in his home (and wasn't sick) it had to be something else! Morris did however stop using arsenic in their papers as the result of public pressure, newspaper reports and a general idea that arsenic was toxic, not just when ingested. Date: 19th century
© Mary Evans / The National Archives, London. England.