Potassium fluoride,anhydrous
           Potassium fluoride,extra pure
           Potassium fluoride,Granular
           Silicon Dioxide
           Hydrofluoric acid
           Synthetic Cryolite
           Potassium Fluoaluminate
           Ammonium bifluoride
           Potassium Bifluoride
           Aluminium fluoride
           Sodium fluoride
           Potassium Fluorosilicate
           Fluorosilicic Acid
           Sodium silicofluoride
           Potassium Hydroxide Flakes
           Magnesium Fluoride
           Magnesium fluorosilicate
           Barium Fluoride
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The chemist Carl Wilhelm Scheele (him again – he just keeps turning up doesn’t he?) was the first person to produce hydrofluoric acid(HF) in large quantities in 1771.  Scheele is particularly famous for his bad habit of sniffing and tasting any new substances he discovered.  Cumulative exposure to mercury, arsenic, lead, their compounds, hydrofluoric acid, and other substances took their toll on him and he died on 21 May 1786 at the age of just 43.  And that’s why your science teacher was endlessly telling you not to eat or drink in the laboratory.

So why is hydrogen fluoride so nasty?  For starters the gas is a severe poison that immediately and permanently damages the lungs and the corneas of the eyes – lovely. Hydrofluoric acid solution is a contact-poison that causes deep, initially painless burns which result in permanent tissue death. It also interferes with calcium metabolism, which means that exposure to it can and does cause cardiac arrest (heart attack) and death. Contact with as little as 160 square centimeters (25 square inches) of skin can kill – that’s about the area of the palm of your hand.

Since Scheele found ashes in phosphorus and other substances. This makes later proved that the bones inside Gunn indeed phosphorus. Before this, people only know that the urine phosphorus, and phosphorus found in bones, from Scheele began. He discovered the role of hydrofluoric acid from fluorspar and sulfuric acid. He took advantage of soft manganese ore and hydrochloric acid to give the chlorine, but mistaken found phlogiston. He wrote to a friend in a letter, he said in 1773: If the soft manganese dissolved in hydrochloric acid, the yellow color is obtained a gas. He also found that the gas has a bleaching effect.