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S. P. L. Sørensen. Søren Peter Lauritz Sørensen (9 January 1868 – 12 February 1939) was a Danish chemist, known for the introduction of the concept of pH, a scale for measuring acidity and alkalinity .
In chemistry, pH ( / piːˈeɪtʃ / pee-AYCH ), also referred to as acidity or basicity, historically denotes " potential of hydrogen " (or "power of hydrogen"). [ 1 ] It is a logarithmic scale used to specify the acidity or basicity of aqueous solutions. Acidic solutions (solutions with higher concentrations of hydrogen ( H+) ions) are ...
History of penicillin. The history of penicillin follows observations and discoveries of evidence of antibiotic activity of the mould Penicillium that led to the development of penicillins that became the first widely used antibiotics. Following the production of a relatively pure compound in 1942, penicillin was the first naturally-derived ...
Beckman model 72 pH meter, 1960. 781 pH/Ion Meter pH meter by Metrohm. A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. [ 2] The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode ...
It is based on the concentration of capsaicinoids, among which capsaicinis the predominant component. [3] The scale is named after its creator, American pharmacist Wilbur Scoville, whose 1912 method is known as the Scoville organoleptictest. [3][4]The Scoville organoleptic test is a subjective assessment derived from the capsaicinoid ...
Heinrich Rudolf Hertz ( / hɜːrts / HURTS; German: [ˈhaɪnʁɪç ˈhɛʁts]; [ 1][ 2] 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell 's equations of electromagnetism. The unit of frequency, cycle per second, was named the ...
Gladys West. Gladys Mae West (née Brown; born October 27, 1930 [1]) is an American mathematician. She is known for her contributions to mathematical modeling of the shape of the Earth, and her work on the development of satellite geodesy models, that were later incorporated into the Global Positioning System (GPS). [2]
Anders Celsius. Anders Celsius ( Swedish pronunciation: [ˈânːdɛʂ ˈsɛ̌lːsɪɵs]; 27 November 1701 – 25 April 1744) [1] was a Swedish astronomer, physicist and mathematician. He was professor of astronomy at Uppsala University from 1730 to 1744, but traveled from 1732 to 1735 visiting notable observatories in Germany, Italy and France.