John Dalton: His Life and Works

John Dalton was an English chemist (also Pioneer Meteorologist), very famous for developing a scientific theory for the ancient hypothesis about ‘atoms’, extremely small, indivisible parts which made up all of matter. Dalton is regarded often as ‘the father of modern chemistry’. His theory has been bedrock for the scientists after him to add to. A lot of contemporary chemistry has been stemmed from his work. Famous scientists that added after him to the atomic theory include: Rutherford, Thompson, Curie, Bohr, Schrödinger/Schroedinger, Mendeleev, Seaborg and Cavendish.

John Dalton’s Life

Early years

John Dalton was born on circa 6^th December, 1776 into a Quaker family (Quakers are part of a religious movement, believing in equal rights and the abolishment of slavery, the religion is still running today). His birthplace was Cumberland, England and, at 12 years of age, had already started to become a teacher and civic lecturer at the local Quaker school. In 1790, after teaching for a couple of years, Dalton moved on to join his brother at another school, as a teacher, offering many subjects to do with maths and science. It is noted that during his stay, he’d gained some popularity, enough for him to be noticed by a rich Quaker called Elihu Robinson, who taught him meteorology, mathematics and other sciences. Robinson was also to be a great influence for John Dalton’s life, and from 1787 onwards, Dalton kept a meteorological diary of observations. Whilst Dalton taught at Kendall, he was mentored by John Gough, a blind, wealthy merchant living nearby the Kendall school. Gough offered Dalton much of his scientific knowledge, and helped him enter the “New School” in Manchester as a teacher of natural philosophy and mathematics. Gough was also a large influence to Dalton, as Dalton’s first two works, “Meteorological Observations and Essays” and “Elements of English Grammar” both respectively published in 1793 and 1801, were dedicated to his “mentor and friend, John Gough.

The “New School”, of Manchester

The school set up in Kendall with the Dalton brothers did not make enough money, though successful. In 1793, Dalton moved Manchester with the help of John Gough, to become a teacher of natural philosophy and maths. In 1794, he became a part of the ‘Manchester Literary and Philosophical Society’. Just shortly after he was elected, he wrote a paper about colour blindness, describing how colour-blind people perceive things and why. Dalton’s (colour-blind himself) “Extraordinary facts relating to the vision of colours” was one of the first papers to officially give an explanation for colour blindness. This paper later became one of his most important and famous papers, even the word, “Daltonism” has become a common name for colour blindness. In his paper, he explains also his own colour-blindness, stating that he saw everything as shades of yellow. Dalton had a rare type of colour blindness called, “deuteroanopia”, which did involve him only seeing yellow, except for blue and purple in a spectrum (This was proven when scientists studied Dalton’s preserved eye.) Dalton, after 6 years as a teacher at Manchester, became a private tutor.

Developing the Atomic Theory

Dalton’s study of gasses led up to his forming of the atomic theory. It is believed he studied gasses because of his great interest in meteorology and especially the atmosphere (Over 200,000 observations were made in his meteorological diaries over 57 years). Dalton published a paper called, “Experimental Essays on the Constitution of Mixed Gases; on the Force of Steam or Vapour from water and other liquids in different temperatures, both in a Torricellian vacuum and in air; on Evaporation; and on the Expansion of Gasses by Heat” (A very long name). This explained how he noticed that when two different gasses mixed with each other, they acted independently, both gasses acted as though the other wasn’t present. He found out that because of this independence, the exerted pressure from the whole mixture of gasses was the same as the sum of different parts of the mixture. Not only that, he was also able to find a mathematical relationship between vapour pressure, and it’s ambient temperature (temperature of matter surrounding the air or the air temperature itself).

However, in 1803, when Dalton tested nitric oxide and oxygen together (in an attempt to produce a third gas), he kept receiving one of two different results, where the ratios between the two gasses were different. Later that year, Dalton was able to conclude his findings in a paper called, “Law of Multiple Proportions”, stating that elements always combined in whole-number ratios, ‘proportions’. Dalton then began writing a table of atomic weights (more popularly known as atomic mass today, although, they can be interchangeable names mostly). His first atomic weight was hydrogen, having a mass of “1”. Though, Dalton had yet to understand the atomic theory yet, even though he’d found out about weights. After reading certain texts, including Democritus’ (Person who originally stated that all matter was composed of small particles) texts, some of Newton’s ideas about ‘balls’ making matter up, and even some Hindu texts about discontinuous matter.

Image taken from http://www.brooklyn.cuny.edu/bc/ahp/FonF/Dalton.htmlDalton was finally able to realise how his Law of Multiple Proportions could work with the atoms idea, and developed the atomic theory. Soon Dalton started creating his own symbols, representing the atoms as spheres. This was a major breakthrough for Chemistry. It was smart to create these symbols because, unlike alphanumeric symbols, they actually gave you an idea about how atoms group together in their proportions.