Developed by Johann Dobereiner in 1829 where he stated that in a group of three elements with similar properties, the weight of the middle element was the average of the mass of the lightest and heaviest elements.(I.e.: Ca, Sr & Ba
Li, Na & K, Cl, Br & I)
1897 - Felix Hoffmann of Bayer made a stable derivative of salicylic acid . This pain-reliever had fewer side effects than the parent acid, and is now known as aspirin.
1902 - Arne Tiselius born: biochemist; electrophoresis; Nobel prize, 1948.
1915 - Henry Moseley, who discovered atomic number, was killed at Gallipoli in World War I.
1897 - 
