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Anestesia.
It's said that true anesthesia was born in the 19th century thanks to the discoveries of gases. Horace Wells is credited with first using nitrous oxide to extract teeth in 1844. But when he had to demonstrate his system at Massachusetts General Hospital, the patient began to scream and Wells fell into disrepute and eventually committed suicide. His colleague, William Morton demonstrated in 1846 the efficacy of ether as a general anesthetic, and in 1847 Simpson applied chloroform in childbirth. -
Darwinism.
Naturalists Charles Darwin and Alfred Russel Wallace independently proposed in 1858 that natural selection was the basic mechanism responsible for the origin of new genotypic variants and ultimately new species. However, it was Darwin himself in The Origin of the species, who synthesized a coherent body of observations and deepened the mechanism of change called natural selection, which consolidated the concept of biological evolution into a true scientific theory. -
Thermionic emission.
The effect was discovered by Thomas Edison on February 13, 1880, while trying to discover the reason why the filaments broke and why the glass darkened of his incandescent lamps.
Edison connected the additional electrode to the filament of the lamp through a galvanometer. However, when it positively charged the foil, most of the electrons emitted from the hot filament were drawn towards it causing a stable current flow -
Discovery of the electron.
In 1896, British physicist Joseph John Thomson, carried out experiments that indicated that cathode rays were actually single particles and not waves, atoms, or molecules, as previously believed. Likewise, it demonstrated that its charge-mass ratio was independent of the cathode material. The name «electron» for these particles was proposed again by the Irish physicist George Francis FitzGerald, and since then the word has gained acceptance in parts. It was finally patented in 1897. -
Aspirina.
Salicylic acid, has been used by mankind for at least 2,400 years.8 Acetylsalicylic acid was first synthesized by French chemist Charles Frédéric Gerhardt in 1853, by combining sodium salicylate with acetyl chloride.9 10 In the second half of the 19th century other chemists described its chemical structure and devised more efficient methods for its synthesis. In 1897, Bayer scientists began studying aspirin as a possible less irritating replacement for common salicylate medications.
