Science, Technology
Science

Why Do We Think What We Do?


Dalton. 1766-1844 J.J Thompson. 1856-1940
Who Was Dalton?? What Did He Think?? Why Did He Think This??

*John Dalton was born in a small thatched cottage in the village of Eaglesfield, Cumberland, England.

*His family were Quakers, and had been for a long time. His Grandfather had converted to this religion in about 1695.

*After a failed attempt to start a school in his home town of Eaglesfield, John Dalton eventually went into partnership with his brother and in 1785 took over a different school in Kendal where the brothers offered a range of subjects including languages and
21 mathematics and science courses! Despite the school's popularity (they had 60 pupils at one point).

*Another person who inspired, instructed and then mentored John Dalton was the blind son of a wealthy Kendal merchant who was very interested in a range of scientific subjects, including optics. John Gough clearly had a significant influence on John Dalton, as the first two books that Dalton published were dedicated to his friend and mentor.

*One suggestion that Gough made to Dalton was to keep a daily log of the weather and matters meteorological. So he started writing down what he saw and what he measured about the weather patterns in a book, every day. He kept this journal for his entire life, and probably the very last thing he did on the day he died, was to make his final entry.

*Manchester was probably the second largest town in England at that time, and was rapidly becoming the industrial center of the world. This is where the famous "industrial revolution" started and the town boasted colleges, libraries and lots of other intellectual stimulants. Dalton joined the Manchester Literary and Philosophical Society and immediately published his first book on Meteorological Observations and Essays.

*In this book Dalton lays out for the first time his ideas on gasses, and that in a mixture of gasses, each gas exists independently of each other gas and acts accordingly. His famous ideas were starting to form.
However, after six years as a college tutor he went private. He gave up the post at the college and offered to tutor individual students privately at the sum of two shillings a session. This allowed him much more time to conduct his own research.

*It was a good move, as he was able to think and perform a series of experiments at this time that led him to the "law" or partial pressures of gasses, which he published in an work entitled 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.

*Here he explained to the world that if two gasses were mixed together they behave as if they were totally independent of each other. The first gas does not attract or repel the second gas, it just behaves as if the second gas did not exist. The result of this "independence" was that the total pressure exerted by the mixture of gasses was the sum of the separate pressures exerted by each part in the mixture.

*He was also able to show that the environment had a measurable affect on the pressure shown by his gasses, and that there was a mathematical relationship between the pressure of a vapor and its ambient temperature.

*Not all gasses interact harmlessly, as Dalton discovered. In 1803 he began to react a gas called nitric oxide (N0) with oxygen to produce a third type of gas. Strangely the result could come out in one of two ways depending on the proportions, or ratios, of the reacting gasses.

*Using one set of conditions it looked like nitrogen was combining with oxygen in the ratio 1 to 1.7, but at other times, in the ratio 1 to 1.3. By August 1803 he had the answer to this puzzle - the "law of multiple proportions" which stated that the weights of elements always combine with one another in ratios that were always whole numbers - thus:


2NO + O ---> N2O3
NO + O ---> NO2

In this way, Dalton was able to start working out a table of atomic weights based on the lightest element, hydrogen, having the arbitrary value of 1.

*While forming these mental images of the physical composition of gasses, Dalton struggled to find words and images he could use to express his ideas. He found two solutions. From his reading of ancient texts, particularly those of Hindu origin, he found the term "atom eater" used by the author Kanda to describe discontinuous matter. Also that the philosopher Democritus had once described water as mostly empty space with smooth balls gliding over each other. The "balls" he called atoms. Newton also contributed the idea that "... God in the beginning formed matter in solid, massey, hard, impenetrable, moveable particles

*This seemed to be the answer. All matter was made up of hard round particles, which he called 'atoms', and that each type of atom, or element, such as hydrogen, oxygen, nitrogen, etc., differed from the next only by its weight.

*The atomic theory had been born.

*But his next idea was one of equal genius; how to represent this idea symbolically so that tiny, invisible particles could be 'seen' and their combining properties studied.

*The solution, so Dalton thought, was to draw circles, each circle representing one of his tiny atomic spheres. Each element could be distinguished by the contents of the circle,

*Using this symbolic representation of invisible atoms, their combining properties could be drawn out, played with, thought about, revised and corrected. It was the perfect way of creating a 'laboratory' where atoms could be moved around at will and placed in a series of relationships that could then be confirmed or denied by actual experiments or data. Today scientists are very comfortable with the idea of model building, and using real or computer models to help them prod and poke around an idea. But in Dalton's day this concept was a major breakthrough.

*The union of atoms into higher order structures could also be represented, So chemical reactions could be studied on paper to see if they conformed to observed fact. A way was open that would take the messy mystery out of the nature of physical matter and make it possible to study its properties and behaviors in a rational and mathematical way.

*On October 21st, 1803, Dalton stood before the Manchester Literary and Philosophical Society (or which he was now the Secretary) and announced to the world the relative weights of the atoms. This fundamental breakthrough in science did not go un-noticed, and he was immediately invited to repeat his announcements before the Royal Institution of London - before a much larger and much more distinguished audience. The word was out, and Dalton's atomic theory began to receive much publicity and debate.

*Some scientists accepted the concepts at once; Thomas Thomson and William Hyde Wollaston. Some were skeptical for as long as 60 years; Charles William Eliot of Harvard University was still not convinced when teaching his classes in 1868. While some were down right hostile; Davy was fanatically opposed and even went as far as to mock the "tall, gaunt, awkward scholar" as Dalton was described by the father of William J. Mayo (who was one of Dalton's pupils).

But as more and more experimental work confirmed the theoretical work, even Davy in later life (about 50 years later) was forced to admit that Dalton was right and that all matter was atomic in nature.

*England is a country that does not like to reward its heroes, a trait that borders on the pathological at times and a theme that recurs in almost every field of endeavor, especially science. So, event though he was over 60 years old, he still had to teach arithmetic to private students to make a living. His friends tried to get him a modest pension from the Government, but were told "... it would be attended with great difficulty". It took a lot of begging and pleading by some influential persons before Lord Grey's government finally and reluctantly provided a modest means of support for one of it's more innovative scientists. It was only 150 pounds a year.

Who Was Thompson?? What Did He Think?? Why Did He Think This??

*Joseph John Thomson was born in Cheetham Hill, a suburb of Manchester on December 18, 1856. He enrolled at Owens College, Manchester, in 1870

*1876 entered Trinity College, Cambridge as a minor scholar. He became a Fellow of Trinity College in 1880, when he was Second Wrangler and Second Smith's Prizeman, and he remained a member of the College for the rest of his life, becoming Lecturer in 1883 and Master in 1918. He was Cavendish Professor of Experimental Physics at Cambridge, where he succeeded Lord Rayleigh, from 1884 to 1918 and Honorary Professor of Physics, Cambridge and Royal Institution, London.

*Thomson's early interest in atomic structure was reflected in his Treatise on the Motion of Vortex Rings which won him the Adams Prize in 1884. His Application of Dynamics to Physics and Chemistry appeared in 1886, and in 1892 he had his Notes on Recent Researches in Electricity and Magnetism published.

*Thomson co-operated with Professor J. H. Poynting in a four-volume textbook of physics, Properties of Matter and in 1895 he produced Elements of the Mathematical Theory of Electricity and Magnetism, the 5th edition of which appeared in 1921.

*In 1896, Thomson visited America to give a course of four lectures, which summarised his current researches, at Princeton. These lectures were subsequently published as Discharge of Electricity through Gases (1897). On his return from America, he achieved the most brilliant work of his life - an original study of cathode rays culminating in the discovery of the electron, which was announced during the course of his evening lecture to the Royal Institution on Friday, April 30, 1897. His book, Conduction of Electricity through Gases, published in 1903 was described by Lord Rayleigh as a review of "Thomson's great days at the Cavendish Laboratory". A later edition, written in collaboration with his son, George, appeared in two volumes (1928 and 1933).

*Thomson returned to America in 1904 to deliver six lectures on electricity and matter at Yale University. They contained some important suggestions as to the structure of the atom. He discovered a method for separating different kinds of atoms and molecules by the use of positive rays, an idea developed by Aston, Dempster and others towards the discovery of many isotopes. In addition to those just mentioned, he wrote the books, The Structure of Light (1907), The Corpuscular Theory of Matter (1907), Rays of Positive Electricity (1913), The Electron in Chemistry (1923) and his autobiography, Recollections and Reflections (1936), among many other publications.

*Thomson, a recipient of the Order of Merit, was knighted in 1908. He was elected Fellow of the Royal Society in 1884 and was President during 1916-1920; he received the Royal and Hughes Medals in 1894 and 1902, and the Copley Medal in 1914. He was awarded the Hodgkins Medal (Smithsonian Institute, Washington) in 1902; the Franklin Medal and Scott Medal (Philadelphia), 1923; the Mascart Medal (Paris), 1927; the Dalton Medal (Manchester), 1931; and the Faraday Medal (Institute of Civil Engineers) in 1938.

*He was President of the British Association in 1909 (and of Section A in 1896 and 1931) and he held honorary doctorate degrees from the Universities of Oxford, Dublin, London, Victoria, Columbia, Cambridge, Durham, Birmingham, Göttingen, Leeds, Oslo, Sorbonne, Edinburgh, Reading, Princeton, Glasgow, Johns Hopkins, Aberdeen, Athens, Cracow and Philadelphia.

*In 1890, he married Rose Elisabeth, daughter of Sir George E. Paget, K.C.B. They had one son, now Sir George Paget Thomson, Emeritus Professor of Physics at London University, who was awarded the Nobel Prize for Physics in 1937, and one daughter.
In 1897 the physicist Joseph John (J. J.) Thomson (1856–1940) discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube—an area being investigated by numerous scientists at the time. Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of "bodies much smaller than atoms" that he calculated as having a very large value for the charge to mass ratio. Later he estimated the value of the charge itself.

*In 1904 he suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. His efforts to estimate the number of electrons in an atom from measurements of the scattering of light, X, beta, and gamma rays initiated the research trajectory along which his student Ernest Rutherford moved. Thomson's last important experimental program focused on determining the nature of positively charged particles. Here his techniques led to the development of the mass spectroscope, an instrument perfected by his assistant, Francis Aston, for which Aston received the Nobel Prize in 1922.

*Ironically, Thomson—great scientist and physics mentor—became a physicist by default. His father intended him to be an engineer, which in those days required an apprenticeship, but his family could not raise the necessary fee. Instead young Thomson attended Owens College, Manchester, which had an excellent science faculty.

*He was then recommended to Trinity College, Cambridge, where he became a mathematical physicist. In 1884 he was named to the prestigious Cavendish Professorship of Experimental Physics at Cambridge, although he had personally done very little experimental work. Even though he was clumsy with his hands, he had a genius for designing apparatus and diagnosing its problems. He was a good lecturer, encouraged his students, and devoted considerable attention to the wider problems of science teaching at university and secondary levels.

*Of all the physicists associated with determining the structure of the atom, Thomson remained most closely aligned to the chemical community because his non-mathematical atomic theory—unlike early quantum theory—could also be used to account for chemical bonding and molecular structure (see Gilbert Newton Lewis and Irving Langmuir). Thomson received various honors, including the Nobel Prize in physics in 1906 and a knighthood in 1908. He also had the great plea
Who Was Rutherford?? What Did He Think?? Why Did He Think This??

*Ernest Rutherford was born on August 30, 1871, in Nelson, New Zealand, the fourth child and second son in a family of seven sons and five daughters. His father James Rutherford, a Scottish wheelwright, emigrated to New Zealand with Ernest's grandfather and the whole family in 1842. His mother, née Martha Thompson, was an English schoolteacher, who, with her widowed mother, also went to live there in 1855.

*Ernest received his early education in Government schools and at the age of 16 entered Nelson Collegiate School. In 1889 he was awarded a University scholarship and he proceeded to the University of New Zealand, Wellington, where he entered Canterbury College.

*He graduated M.A. in 1893 with a double first in Mathematics and Physical Science and he continued with research work at the College for a short time, receiving the B.Sc. degree the following year. That same year, 1894, he was awarded an 1851 Exhibition Science Scholarship, enabling him to go to Trinity College, Cambridge, as a research student at the Cavendish Laboratory under J.J. Thomson.

*In 1897 he was awarded the B.A. Research Degree and the Coutts-Trotter Studentship of Trinity College. An opportunity came when the Macdonald Chair of Physics at McGill University, Montreal, became vacant, and in 1898 he left for Canada to take up the post.

*Rutherford returned to England in 1907 to become Langworthy Professor of Physics in the University of Manchester, succeeding Sir Arthur Schuster, and in 1919 he accepted an invitation to succeed Sir Joseph Thomson as Cavendish Professor of Physics at Cambridge. He also became Chairman of the Advisory Council, H.M. Government, Department of Scientific and Industrial Research; Professor of Natural Philosophy, Royal Institution, London; and Director of the Royal Society Mond Laboratory, Cambridge.

*Rutherford's first researches, in New Zealand, were concerned with the magnetic properties of iron exposed to high-frequency oscillations, and his thesis was entitled Magnetization of Iron by High-Frequency Discharges. He was one of the first to design highly original experiments with high-frequency, alternating currents.

*His second paper, Magnetic Viscosity, was published in the Transactions of the New Zealand Institute (1896) and contains a description of a time-apparatus capable of measuring time intervals of a hundred-thousandth of a second.

*On his arrival at Cambridge his talents were quickly recognized by Professor Thomson. During his first spell at the Cavendish Laboratory, he invented a detector for electromagnetic waves, an essential feature being an ingenious magnetizing coil containing tiny bundles of magnetized iron wire. He worked jointly with Thomson on the behaviour of the ions observed in gases which had been treated with X-rays, and also, in 1897, on the mobility of ions in relation to the strength of the electric field, and on related topics such as the photoelectric effect. In 1898 he reported the existence of alpha and beta rays in uranium radiation and indicated some of their properties.


*In Montreal, there were ample opportunities for research at McGill, and his work on radioactive bodies, particularly on the emission of alpha rays, was continued in the Macdonald Laboratory. With R.B. Owens he studied the "emanation" of thorium and discovered a new noble gas, an isotope of radon, which was later to be known as thoron.

* Frederick Soddy arrived at McGill in 1900 from Oxford, and he collaborated with Rutherford in creating the "disintegration theory" of radioactivity which regards radioactive phenomena as atomic - not molecular - processes. The theory was supported by a large amount of experimental evidence, a number of new radioactive substances were discovered and their position in the series of transformations was fixed. Otto Hahn, who later discovered atomic fission, worked under Rutherford at the Montreal Laboratory in 1905-06.

*At Manchester, Rutherford continued his research on the properties of the radium emanation and of the alpha rays and, in conjunction with H. Geiger, a method of detecting a single alpha particle and counting the number emitted from radium was devised. In 1910, his investigations into the scattering of alpha rays and the nature of the inner structure of the atom which caused such scattering led to the postulation of his concept of the "nucleus", his greatest contribution to physics.

*According to him practically the whole mass of the atom and at the same time all positive charge of the atom is concentrated in a minute space at the centre. In 1912 Niels Bohr joined him at Manchester and he adapted Rutherford's nuclear structure to Max Planck's quantum theory and so obtained a theory of atomic structure which, with later improvements

*mainly as a result of Heisenberg's concepts, remains valid to this day. In 1913, together with H. G. Moseley, he used cathode rays to bombard atoms of various elements and showed that the inner structures correspond with a group of lines which characterize the elements. Each element could then be assigned an atomic number and, more important, the properties of each element could be defined by this number. In 1919, during his last year at Manchester, he discovered that the nuclei of certain light elements, such as nitrogen, could be "disintegrated" by the impact of energetic alpha particles coming from some radioactive source, and that during this process fast protons were emitted.

*An inspiring leader of the Cavendish Laboratory, he steered numerous future Nobel Prize winners towards their great achievements: Chadwick, Blackett, Cockcroft and Walton; while other laureates worked with him at the Cavendish for shorter or longer periods: G.P. Thomson, Appleton, Powell, and Aston. C.D. Ellis, his co-author in 1919 and 1930, pointed out "that the majority of the experiments at the Cavendish were really started by Rutherford's direct or indirect suggestion". He remained active and working to the very end of his life.

*Rutherford published several books: Radioactivity (1904); Radioactive Transformations (1906), being his Silliman Lectures at Yale University; Radiation from Radioactive Substances, with James Chadwick and C.D. Ellis (1919, 1930) - a thoroughly documented book which serves as a chronological list of his many papers to learned societies, etc.; The Electrical Structure of Matter (1926); The Artificial Transmutation of the Elements (1933); The Newer Alchemy (1937).

*Rutherford was knighted in 1914; he was appointed to the Order of Merit in 1925, and in 1931 he was created First Baron Rutherford of Nelson, New Zealand, and Cambridge. He was elected Fellow of the Royal Society in 1903 and was its President from 1925 to 1930. Amongst his many honours, he was awarded the Rumford Medal (1905) and the Copley Medal (1922) of the Royal Society

*the Bressa Prize (1910) of the Turin Academy of Science, the Albert Medal (1928) of the Royal Society of Arts, the Faraday Medal (1930) of the Institution of Electrical Engineers, the D.Sc. degree of the University of New Zealand, and honorary doctorates from the Universities of Pennsylvania, Wisconsin, McGill, Birmingham, Edinburgh, Melbourne, Yale, Glasgow, Giessen, Copenhagen, Cambridge, Dublin, Durham, Oxford, Liverpool, Toronto, Bristol, Cape Town, London and Leeds.

*Rutherford married Mary Newton, only daughter of Arthur and Mary de Renzy Newton, in 1900. Their only child, Eileen, married the physicist R.H. Fowler. Rutherford's chief recreations were golf and motoring.

He died in Cambridge on October 19, 1937. His ashes were buried in the nave of Westminster Abbey, just west of Sir Isaac Newton's tomb and by that of Lord Kelvin.

From Nobel Lectures, Chemistry 1901-1921, Elsevier Publishing Company, Amsterdam, 1966


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