We lived at Eaglesfield in Cumberland in a small thatched cottage when my brother John was born. I was seven and our sister, Mary, was two. John's birth was not recorded in the family Bible, but when he asked later, the old people told him it was 5 September 1766. Our family had been Quakers since the 1690's when Grandfather Jonathan, my namesake, converted. Grandmother Abigail was a Fearon whose dowry brought our family a holding, which Grandfather enlarged to sixty acres. My father Joseph, their second son, inherited this estate. My mother was Deborah Greenup of a Quaker farming family. John and I helped with the field work and in the shop where my father wove cloth. Mary helped Mother with the house and sold paper, ink and quills. Although we were not hungry, we were poor. Other poor boys received little education, but as Quakers, we Dalton children received an empirical and utilitarian education at the nearest Quaker school. This was quite a feat since, at that time, only one of every 215 English people could read.
John and I went to the Quaker school at Pardshow Hall. John was quick at studies and tireless at mathematical problems. John Fletcher, the master, was a superior man who did not use the rod to hammer in learning. He was to provide John with a superb background and lifelong quest for knowledge. Elihu Robinson, a rich Quaker gentleman, became John's mentor and another source of mental stimulation in mathematics and science, especially meteorology.
When my brother was twelve, he opened a school in Eaglesfield. He was threatened by the older boys who wanted to fight with the young master, but apparently he managed to control them for two years. Due to the poor salary, John returned to the land briefly and worked for our rich uncle. Meanwhile, I had left home to assist George Bewley with his school at Kendall. When John joined me in 1781, we planned to run the school together when cousin George retired. In 1785 our school opened and we offered English, Latin, Greek, French, along with twenty-one mathematics and science subjects. Mary came to keep house for us. Although we had sixty pupils, we were often forced to borrow and take outside jobs to support ourselves.
For the twelve years at Kendall, John worked at self improvement, including answering questions from ladies' and gentlemen's magazines. His responses appeared in print sixty times. John found a new friend and mentor in John Gough, the blind son of a wealthy tradesman, he taught John languages, mathematics and optics, and shared his extensive library. Later, John dedicated his earliest two books to Gough who had encouraged his lifelong interest in meteorology by suggesting that John keep a daily journal. As John's interest in science expanded to include optics, pneumatics, astronomy and geography, he began in 1787 to supplement his low income with public lectures. He also approached a nearby museum with an offer to sell his eleven volume classified botanical collection. He collected butterflies and studied snails, mites and maggots by suspending them in water and vacuums. He measured his own intake of food to compare with his production of waste. His studies were to prepare him to go to medical school, but we discouraged him because we lacked the money and did not feel that John was suited to be a physician.
Once, on our mother's birthday, John bought her some very special stockings. This was to be a treat for she always wore homespun stockings. Mother exclaimed to John, "Why did you buy me scarlet stockings?" John had thought they were blue and turned to me to verify their suitable color. Since we both saw blue instead of scarlet, Mother took the stockings out to some of the other women. So at the age of twenty -six, John discovered that we were both color-blind. John experimented and wrote about this phenomenon in his first important scientific paper. Many years later when John had an audience with the King, he refused to wear the customary dress which included a sword. In a compromise, he agreed to wear his Oxford honorary doctoral robe. John thought the robe was grey, but in reality it was red, which at that time was not an appropriate color for a Quaker. The condition of color-blindness came to be known as Daltonism in France.
In 1793, John moved to Manchester as tutor at New College founded by the Presbyterians. It was here that John would rise above his country schoolteacher background to do his greatest work. He immediately joined the Manchester Literary and Philosophical Society. In 1793, he published his first book, Meteorological Observations and Essays. In it he said that each gas exists and acts independently and purely physically, rather than chemically. This means that gases act according to mechanical repulsion rather than chemical attraction. As a chemistry tutor, John taught from Lavoisier's Elements of Chemistry. After six years John resigned to conduct private research supported by tutoring at two shillings a lesson.
In 1802, in the grandly titled "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," John stated his law of partial pressures. He explained that when two elastic fluids, A and B, are mixed together, there is no mutual repulsion between their particles; that is, A particles do not repel B particles, but a B particle will repel another B. Consequently, the pressure or whole weight of the gas arises solely from its particles. One of his experiments involved the addition of water vapor to dry air. The increase in pressure was the same as the pressure of the added water. He also established a relationship between vapor pressure and temperature.
John's interest in gases arose from his meteorological studies. He always carried his weather apparatus with him wherever he went, even on his infrequent vacations. He was constantly studying the weather and atmosphere. During his lifetime, John made over 200,000 observations, which he wrote in a journal, his constant companion. It was in these observations that his mathematical mind saw the numerical connections between the data.
In 1803, while attempting to explain his law of partial pressures, John started to formulate his most important contribution to science the atomic theory. He was studying nitrogen oxides for Dr. Priestley's test for percentage of nitrogen in the air. Among the reactions he studied were those of nitric oxide with oxygen. He discovered that the reaction can take place in two different porportions in exact ratios, namely:
John stated that oxygen combines with nitrogen sometimes 1 to 1.7 and at other times 1 to 3.4 by weight. On 4 August 1803, he stated the law of multiple porportions: the weights of elements always combine with each other in small whole number ratios. John published his first list of atomic weights and symbols that year, which gave chemistry a language of its own.
The ensuing years were very busy for my brother. He lectured, tutored, and of course, experimented. He orally reported the results of the experiments at the "Lit and Phil" and published them in a book in 1808. This was his most famous work, A New System of Chemical Philosophy, Part I. On page 71 he states, "No two elastic fluids, probably, therefore have the same number of particles or the same weight." John had relied on his observations and mathematical reasoning to produce a revolutionary book containing a revolutionary theory. His train of reasoning from his "rule of greatest simplicity" (all combinations of atoms occur in the simplest possible) to his belief in the caloric theory led him to this theory. John adopted the idea of atoms and drew individual particles to illustrate chemical reactions.
Not everyone accepted the atomic theory and John had to defend it from critics. In 1810, he published Part II of his New System, giving more empirical evidence for it. It was amazing to me that my little brother John could have produced the theory which quantified chemical theory.
John died on 27 July 1844 of a stroke, after noting the weather conditions for the day in his journal. He had requested an autopsy to determine the cause of his color-blindness. It was his final experiment and proved that the condition called Daltonism is not caused by the eye itself, but some deficient sensory power. Manchester buried John with kingly honors with his body lying in state and a funeral as for a monarch. John was viewed by more than 400,000 people while his body lay in state and the procession was over a mile long. This was in direct violation to the simple Quaker principles by which John had lived. Furthermore,the city has honored him with both a large monument and a statue.
J. Dalton, J. Gay-Lussac, and A. Avogadro, Foundation of the Molecular Theory: Comprising Papers and Extracts, The University of Chicago Press, Chicago, 1906, pp. 5-7
D.A. Davenport, "John Dalton's First Paper and Last Experiment", ChemMatters, 1984, April, p.14.
J. T. Moore, A History of Chemistry, McGraw-Hill Book, Co., Inc., New York, London, 1939, pp.115-131.
E.C. Patterson, John Dalton and the Atomic Theory, Doubleday and Co, Inc., Garden City, New York, 1970.
A.J. Rocke, Chemical Atomism in the Nineteenth Century, Ohio State University Press, Columbus, Ohio, 1984, pp.21-43.
H.E. Roscoe, John Dalton and the Rise of Modern Chemistry, MacMillan and Co., New York and London, 1895.
T. Thomson, The History of Chemistry, Arno Press, New York, 1975, pp.277-308.
A. G. VanMelsen, From Atomos to Atom, Harper Torchbooks, The Science Library, New York, 1952, pp. 136-138.
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