The scientific field has witnessed the emergence of many great
physicists and chemists; but it is incomplete without the mention of the
great British chemist, meteorologist and physicist John Dalton. His
tremendous efforts led to the evolution of modern atomic theory. He was
the first person to record color blindness. He also carried out his
research to explain the shortage of color perception.
Dalton was born into a modest Quaker family in Cumberland, England
around 5th September 1766. He got his early education from his father
and his teacher, John Fletcher of the Quakers’ school at Eaglesfield, on
whose retirement in 1778 he himself began teaching. He spent most of
his life teaching and giving public lectures. After serving ten years at
a Quaker boarding school in Kendal, in 1793 he took another teaching
position in the rapidly increasing city of Manchester. There he taught
math and natural philosophy at the “New College” until 1800, when he
resigned due to worsening financial condition of the college. Afterwards
he gave private tuitions for mathematics and natural philosophy.
Most of the credit of Dalton’s interests in mathematics and
meteorology goes to Elihu Robinson, an experienced meteorologist and
instrument maker who greatly influenced his initial years of life. At
Kendal, Dalton proposed solutions of problems and questions on various
subjects to the Gentlemen’s and Ladies’ Diaries, and starting in 1787 he
maintained a meteorological diary in which during the succeeding
fifty-seven years he entered over 200,000 observations.
His first separate publication was Meteorological Observations and
Essays (1793), which explained many of his later discoveries; but in
spite of the originality of its content, the book met with only a
limited attention. Another work by him was published in 1801 as Elements
of English Grammar.
In 1794 John joined the Manchester Literary and Philosophical
Society, which provided him with an exciting academic environment and
laboratory services. After few weeks he presented his first paper on
“Extraordinary facts relating to the vision of colors” before the
society. In this paper he explained that the shortage in color
perception was caused by discoloration of the liquid medium of the
eyeball. He himself was a victim of color blindness and was the first
one to discover the concept. As a result ‘Daltonism’ became synonymous
with color blindness.
Dalton’s greatest interest was in meteorology and he maintained daily
records of local temperature, wind, humidity and atmospheric pressure
using instruments that he devised himself. By 1800 he was appointed the
secretary of the Manchester Literary and Philosophical Society and
published a series of papers entitled “Experimental Essays on the
constitution of mixed gases; on the force of steam or vapor of water and
other liquids in different temperatures, both in Torricellian vacuum
and in air; on evaporation; and on the expansion of gases by heat.”
In 1803, he published his gas law which is now known as ‘Dalton’s
law.’ In this law he basically stated that the total pressure exerted by
a gaseous mixture is equal to the sum of the partial pressures of each
individual component in a gas mixture.
He calculated atomic weights of elements and assembled them in a
table which consisted of six elements namely hydrogen, oxygen, nitrogen,
carbon, sulfur, and phosphorus. He calculated these weights from
percentage compositions of compounds using an arbitrary system to
determine the probable atomic structure of each compound.
John Dalton’s Atomic theory has three principles that remain
relatively unchanged. First, Elements are made of the smallest particles
called atoms. Second, all atoms for a particular element are identical.
Third, atoms of different elements can be told apart by their atomic
weight. Fourth, atoms of different elements can combine in a chemical
reaction to form chemical compounds in fixed ratios. Finally, atoms can
not be created, destroyed, or divided as they are the smallest particles
of matter. Even though some of its postulates were opposed by many
scholars and scientists, Dalton’s Atomic Theory stills holds a lot of
significance as it created a basis for current science.
Dalton died of a stroke on 27 July, 1844 and was buried in Manchester in Ardwick cemetery.
