Source : https://id.wikipedia.org/wiki/John_Dalton

Early life

John Dalton was born into a Quaker family from Eaglesfield, near Cockermouth, in Cumberland, England. His father was a weaver. He received his early education from his father and from Quaker John Fletcher, who ran a private school in the nearby village of Pardshaw Hall. Dalton's family was too poor to support him for long and he began to earn his living, from the age of ten, in the service of a wealthy local Quaker, Elihu Robinson.

John Dalton FRS (/ˈdɔːltən/; September 6, 1766 - July 27, 1844) was an English chemist, physicist, and meteorologist. He is best known for introducing atomic theory into chemistry, and for his research on color blindness, sometimes referred to as Daltonism in his honor.

Early career

When he was 15 years old, Dalton joined his older brother Jonathan in running Quaker school in Kendal, Westmorland, about 45 miles (72 km) from his home. Around the age of 23 Dalton may have considered studying law or medicine, but his relatives did not support him, perhaps because of being a Dissenter, he was barred from entering a British university. He gained a lot of scientific knowledge from informal instruction by John Gough, a blind philosopher talented in science and art. At the age of 27 he was appointed teacher of mathematics and natural philosophy at 'New College' in Manchester, a dissenting academy (linear predecessor, following a number of location changes, from Harris Manchester College, Oxford). She remained there until the age of 34.

When the college's deteriorating financial situation led him to resign from his post and begin a new career as a private teacher in mathematics and natural philosophy.

Dalton's early life was influenced by a prominent Quaker, Elihu Robinson, a competent meteorologist and instrument maker, from Eaglesfield, Cumbria, who interested him in problems of mathematics and meteorology. During his years in Kendal, Dalton contributed solutions to problems and answered questions on various subjects in The Ladies' Diary and the Gentleman's Diary. In 1787 at age 21 he began his meteorological diary in which, during the succeeding 57 years, he entered more than 200,000 observations. He rediscovered George Hadley's theory of atmospheric circulation (now known as the Hadley cell) around this time. In 1793 Dalton's first publication, Meteorological Observations and Essays, contained the seeds of several of his later discoveries but despite the originality of his treatment, little attention was paid to them by other scholars. A second work by Dalton, Elements of English Grammar (or A new system of grammatical instruction: for the use of schools and academies), was published in 1801.

After leaving the Lake District, Dalton returned annually to spend his holidays studying meteorology, something which involved a lot of hill-walking. Until the advent of aeroplanes and weather balloons, the only way to make measurements of temperature and humidity at altitude was to climb a mountain. Dalton estimated the height using a barometer. The Ordnance Survey did not publish maps for the Lake District until the 1860s. Before then, Dalton was one of the few authorities on the heights of the region's mountains. He was often accompanied by Jonathan Otley, who also made a study of the heights of the local peaks, using Dalton's figures as a comparison to check his work. Otley published his information in his map of 1818. Otley became both an assistant and a friend to Dalton.

In 1794, shortly after his arrival in Manchester, Dalton was elected a member of the Manchester Literary and Philosophical Society, the "Lit & Phil", and a few weeks later he communicated his first paper on "Extraordinary facts relating to the vision of colours", in which he postulated that shortage in colour perception was caused by discoloration of the liquid medium of the eyeball. As both he and his brother were colour blind, he recognised that the condition must be hereditary.

Although Dalton's theory was later disproven, his early research into colour vision deficiency was recognized after his lifetime. Examination of his preserved eyeball in 1995 demonstrated that Dalton had deuteranopia, a type of Congenital red-green color blindness in which the gene for medium wavelength sensitive (green) photopsins is missing. Individuals with this form of colour blindness see every color as mapped to blue, yellow or gray, or, as Dalton wrote in his seminal paper,

In 1800, Dalton became secretary of the Manchester Literary and Philosophical Society, and in the following year he presented an important series of lectures, entitled "Experimental Essays" on the constitution of mixed gases; the pressure of steam and other vapoursat different temperatures in a vacuum and in air; on evaporation; and on the thermal expansion of gases. The four essays, presented between 2 and 30 October 1801, were published in the Memoirs of the Literary and Philosophical Society of Manchester in 1802.

The second essay opens with the remark,

After describing experiments to ascertain the pressure of steam at various points between 0 and 100 °C (32 and 212 °F), Dalton concluded from observations of the vapour pressure of six different liquids, that the variation of vapour pressure for all liquids is equivalent, for the same variation of temperature, reckoning from vapour of any given pressure.

In the fourth essay he remarks,

He enunciated Gay-Lussac's law, published in 1802 by Joseph Louis Gay-Lussac (Gay-Lussac credited the discovery to unpublished work from the 1780s by Jacques Charles). In the two or three years following the lectures, Dalton published several papers on similar topics. "On the Absorption of Gases by Water and other Liquids" (read as a lecture on 21 October 1803, first published in 1805) contained his law of partial pressures now known as Dalton's law.

If two types of elements combine to form more than one compound and if the mass of one element in the compound is the same, while the mass of the other elements is different