Biography of John Dalton
Dalton, John (b. Sept. 6, 1766, Eaglesfield,
Cumberland. Eng.- d. July 27, 1844, Manchester),
British chemist and physicist who developed the
atomic theory of matter and hence is known as one of
the fathers of modern physical science.
Dalton was the son of a Quaker weaver. When only 12
he took charge of a Quaker school in Cumberland and
John Dalton, detail of an engraving by W.
Worhington, after a portrait by William
Allen, 1814
two years later taught with his brother at a school in
Kendal, where he was to remain for 12 years. He then
became a teacher of mathematics and natural philosophy at New College in
Manchester, a college established by the Presbyterians to give a first-class
education to both layman and candidates for the ministry, the doors of
Cambridge and Oxford being
open at that time only to
members of the Church of
England. He resigned this
position in 1800 to become
secretary of the Manchester
Literary and Philosophical
Society and served as a public
and private teacher of
mathematics and chemistry. In
1817 he became president of the
Philosophical Society, an
honorary office that he held until
his death
In the early days of his teaching, Dalton's way of life was influenced by a wealthy
Quaker, a capable meteorologist and instrument maker, who interested him in
the problems of mathematics and meteorology. His first scientific work, which he
began in 1787 and continued until the end of his life, was to keep a diary - which
was ultimately to contain 200,000 entries - of meteorological observations
recording the changeable climate of the lake district in which he lived. In 1793
Dalton published Meteorological Observations and Essays. He then became
interested in preparing collections of botanical and insect species. Stimulated by
a spectacular aurora display in 1788, he began observations about aurora
phenomena - luminous, sometimes colored displays in the sky caused by
electrical disturbances in the atmosphere. His writings on the aurora borealis
reveal independent thinking unhampered by the conclusions of others. As Dalton
himself notes, "Having been in my progress so often misled by taking for granted
the results of others, I have determined to write as little as possible but what I
can attest by my own experience." In his work on the aurora he concluded that
some relationship must exist between the aurora beams and the Earth's
magnetism: "Now, from the conclusions in the preceding sections, we are under
the necessity of considering the beams of the aurora borealis of a ferruginous
(iron-like) nature, because nothing else is known to be magnetic, and
consequently, that there exists in the higher regions of the atmosphere an elastic
fluid partaking of the properties of iron, or rather of magnetic steel, and that this
fluid, doubtless from its magnetic property, assumes the form of cylindric beams."
Color Blindness
color blindness, inability to distinguish one or
Some of his studies in meteorology led more of the three colors red, green, and blue.
him to conclusions about the origin of (Ability to see color exists in only a few
vertebrates, including, among others, man and
trade winds involving the Earth's
the other primates, fish, amphibians, some
rotation and variation in temperature -
reptiles, and some birds; and in bees and
unaware, perhaps, that this theory had butterflies.) In the retina, the light-sensitive layer
already been proposed in 1735 by of tissue that lines the back and sides of the
George Hadley. These are only some eyeball, there are, in human beings, three types
of cones, the visual cells that function in the
of the subjects on which he wrote
perception of color. One type absorbs light best in
essays that he read before the
wavelengths of blue-violet and another in the
Philosophical Society: others included wavelengths of green. The third type is most
such topics as the barometer, sensitive to wavelengths of yellow but is also
thermometer, hygrometer, rainfall, the sensitive to red.
formation of clouds, evaporation and
Color-blind persons may be blind to one, two,
distribution and character of
or all of the colors red, green, and blue.
atmospheric moisture, including the (Blindness to red is called protanopia; to green,
concept of the dew point. He was the deuteranopia; and to blue, tritaopia.) Red-blind
first to confirm the theory that rain is persons are ordinarily unable to distinguish
between red and green, while blue-blind persons
caused not by any alteration in
cannot distinguish between blue and yellow.
atmospheric pressure but by a
Green-blind persons are unable to see the green
diminution of temperature. In his part of the spectrum.
studies with water he determined the
point of the maximum density of water Color blindness, which affects about 20 times
as many males as females, is a sex-linked
to be 42.5° F (later shown to be 39.16°
recessive characteristic. A woman must inherit
F. Along with his other researches he
the trait from both parents to be color-blind. A
also became interested in color color-blind man and a woman of normal color
blindness, a condition that he and his vision have daughters who have normal color
brother shared. The results of this vision but are carriers of the trait that is, the
daughters may have color-blind sons and
work were published in an essay,
daughters who are carriers. The sons of a color-
"Extraordinary Facts Relating to the
blind man and a woman with normal vision
Vision of Colors" (1794), in which he themselves have normal vision and are unable to
pass the color-blind trait on to offspring. The son
of a normal man and a carrier woman may be
color-blind, and the daughter of such a union may
be a carrier. Thus, color blindness tends to skip
generations.
postulated that deficiency in color perception was caused by discoloration of the
liquid medium of the eyeball. Although Dalton's theory lost credence in his own
lifetime, the meticulous, systematic nature of his research was so broadly
recognized that Daltonism became a common term for color blindness.
An indefatigable investigator or researcher, Dalton had an unusual talent for
formulating a theory from a variety of data. The mental capacity of the man is
illustrated by his major work that was to begin at the turn of the century - his work
in chemistry. Although he taught chemistry for six years at New College, he had
no experience in chemical research. He embarked on this study with the same
intuitiveness, independence of mind, dedication, and genius for creative
synthesis of a theory from the available facts that he had demonstrated in his
other work. His early studies on gases led to development of the law of partial
pressures (known as Dalton's law; q.v.), which states that the total pressure of a
mixture of gases equals the sum of the pressures of the gases in the mixture,
each gas acting independently. These experiments also resulted in his theory
according to which gas expands as it rises in temperature (the so-called
Charles's law, which should really be credited to Dalton). On the strength of the
data gained in these studies he devised other experiments that proved the
solubility of gases in water and the rate of diffusion of gases. His analysis of the
atmosphere showed it to be constant in com-position to 15,000 feet. He devised
a system of chemical symbols and, having ascertained the relative weights of
atoms (particles of matter), in 1803 arranged them into a table. In addition, he
formulated the theory that a chemical combination of different elements occurs in
simple numerical ratios by weight, which led to the development of the laws of
definite and multiple proportions. Dalton discovered butylene and determined the
composition of ether, finding its correct formula. Finally, he developed his
masterpiece of synthesis - the atomic theory, the thesis that all elements are
composed of tiny, indestructible particles called atoms that are all alike and have
the same atomic weight.
Dalton's studies and writings,
many included in his New System
of Chemical Philosophy (part I,
1808; part II, 1810), cast light on
the man. Dedicated to scientific
research, independent in his
approach, often diffident in
seeking help in scientific papers
that would aid him - or misguide
him, as he often thought - he was
a genius in synthesizing facts and
ideas. Almost a recluse, with few
friends, and unmarried, he was
deeply dedicated to a search for
the answer to scientific problems.
His homemade equipment was
crude, and his data were not
usually exact, but they were good
enough to give his alert and
creative mind clues to the probable answer. Dalton remained a man of simple
wants and uniform habits, keeping his dress and manners consistent with his
Quaker faith.
Dalton's record keeping, although remarkable for quantity, often lacked
exactness in dating, probably because he revised his manuscripts as secretary of
the Philosophical Society between the time of the oral presentation and the
publication. The exact date of some of his work, especially the atomic theory, is
still in doubt because of this opportunity for revision. His documents were
destroyed during the bombings of England in World War II. A fellow of the Royal
Society, from whom he received the Gold Medal in 1826, and a corresponding
member of the French Academy of Sciences, John Dalton was also cofounder of
the British Association for the Advancement of Science. At his death more than
40,000 people came to Manchester to pay their final respects. (A.B.Ga.)
BIBLIOGRAPHY. H.E. Roscoe, John Dalton and the Rise of Modern Chemistry (1895), the most
authoritative biography, and with A. Harden. A New View of the Origin of Dalton's Atomic Theory
(1896), original material on Dalton's research: D.S.L. Cardwell (ed.), John Dalton and the
Progress of Science (1968); J.B. Conant and L.K. Nash (eds.), Harvard Case Histories in
Experimental Science, vol. 1 (1957), probably the most critical analysis of Dalton's work; Frank
Greenaway. John Dalton and the Atom (1966).