John Dalton Bicentenary Meeting

The Society held a meeting on 21 October 2003 in the Cardwell Auditorium of the Manchester Museum of Science and Industry to celebrate the 200th anniversary of Dalton's first announcement of his atomic theory. Papers were given by Dr Diana Leitch and John Woodhouse, Dr Howard Oliver, Mrs Raj Williamson-Jones, Prof. Mel Usselman and Dr Katherine Watson, and John Hudson.

Diana Leitch and John Woodhouse gave a paper on "The Dalton Archives". Dr Leitch described how the majority of Dalton's manuscripts had been destroyed when the premises of the Manchester Lit. and Phil. were consumed by fire after a bombing raid in 1940. However a significant number of papers contained in a metal box in the basement did survive, although badly charred. In 1979 these were sold by the Lit. and Phil. to the John Rylands University Library of Manchester. The manuscripts were in urgent need of conservation, and in 1991 the North West Region Committee of the Industrial Division of the Royal Society of Chemistry provided substantial funds for the necessary work to be undertaken. John Woodhouse then described the conservation process which had been carried out under his supervision. The paper had become very acidic, and each page had to be sprayed with a solution of methyl magnesium carbonate. The paper was so fragile that it was necessary to support the pages in enclosures made of PVC-coated glass fibre mesh during the deacidification process. It was then necessary to find a method of enabling the papers to be handled without further disintegration. The manuscript pages were individually encapsulated and sealed in clear polyester wallets, and then bound into specially made folders. As a result of this work the surviving documents can now be consulted by researchers. Attendees were able to inspect some of the conserved materials during the lunch break.

Howard Oliver's paper on "Dalton's Meteorology" described how Dalton's interest in meteorology was fired during his time at Kendal by his contacts with John Gough. He then began regular observations which he continued, quite literally, for the rest of his life. He published the first edition of his textbook Meteorological Observations and Essays shortly after taking up his position at the Manchester Academy – which has subsequently evolved into Harris Manchester College at Oxford. The book contains both detailed observations made by himself at Kendal and his friend Peter Crossthwaite at Keswick plus a series of articles on meteorological processes and the aurora. He published a second edition containing additional data some forty years later. During his time as the 'professor of mathematics and natural philosophy' he continued his observations and worked on what is one of his most important papers: Experiments and observations to determine whether the quantity of rain and dew is equal to the quantity of water carried off by the rivers and raised by evaporation. This presented the first quantitative water balance of England and Wales which, despite sparse information, provided the first confirmation of the probable hydrological balance for a large area – a topic which had been a matter of contention since classical times. It is for this reason that the European Geophysical Society named their award for hydrology the 'Dalton Medal'.

Dalton's works on evaporation culminated with the publication of important tables of evaporation rates for a range of temperatures and wind speeds. His evaporation process law still forms the basis of the equations in use today. His interest in the natural environment, fuelled by his Quaker enthusiasm for developing an understanding of the workings of God's world, was satisfied by his annual visits to the Lakes and his mountain excursions. He combined these climbs, often made with the guide Jonathan Otley, with meteorological measurements of air temperature and dewpoint to support his studies of mountain climatology and atmospheric composition. In 1842 he published his last meteorological paper which provided summaries of his measurements of the Manchester climate from 1794 to 1840 – an amazing achievement. The evening before his death, Dalton made the last of his 200,000 meteorological observations. Many of his records survived until 1940.

Raj Williamson-Jones's paper was entitled "A New Light on Dalton's Atomic Theory: The Manchester Gas Affair". Using previously unpublished papers and new sources, she described Dalton's extensive contributions to the coal gas industry from the first use of gas as an illuminant in the opening years of the 19th century. This is an aspect of Dalton's multifaceted activities that was not known before. Dalton's study of mixed gases, such as their partial pressures, diffusion, and behaviour on heating - and particularly of their solubilities, which led him to the idea of atomic weights – were contributory to the understanding of the science of coal gas. Dalton also established the composition of several hydrocarbons in coal gas, e.g. methane, a major constituent, ethylene, and butylene. Dalton's friend and collaborator, William Henry, who had close connections with the firm of Boulton and Watt, the pioneers of coal gas industry, also played a significant part in the rapid establishment of coal gas as a public utility.

Many mills and large institutions installed their own gas works. The Chartered Gas Light and Coke Company of London built the first public gas supply in 1812 and its Chief Engineer, Samuel Clegg, was a former pupil of Dalton. Manchester established its gas works in 1817, but unlike other provincial towns, where the gas industry developed as a private enterprise, Manchester, the home of laissez faire, paradoxically chose to build it out of rates. It became the first and for some time the only municipal gas works in the country. It served as a model for other enterprises, such as water works, tramways, electricity stations and the Manchester ship canal

In the 1820s, however, the legality of the gas venture was challenged and it faced severe competition from a private joint stock company, The Manchester Imperial Oil Gas Company. Manchester opposed the granting of a charter to its rival, and presented its own bill to legitimise its municipal gas enterprise. Dalton spent two weeks in the spring of 1824 on behalf of Manchester along with other members of the Gas Committee giving evidence to a parliamentary select committee. Manchester triumphed and the gas enterprise evolved into the largest in the region. Dalton was a recognised authority in the coal gas industry, and acted as a consultant to the Manchester Gas Committee for many years.

Mel Usselman and Katherine Watson gave a paper entitled "A Reconstruction and Analysis of the Contentious Nitrous Gas Experiments". They described how in October and November of 1803 Dalton performed simple experiments on the combination of nitrous gas [NO] with the oxygen in atmospheric air which demonstrated that nitrous gas reacted with oxygen in a 1:1.8 volume ratio to form nitric acid, and in a 1:3.6 ratio to form nitrous acid. The result is Dalton's first experimental report of multiple combining proportions and, as such, played an important role in the development of his atomic ideas. Some prominent historians of chemistry have questioned the reliability of Dalton's result and there are even published claims that Dalton 'fudged' his numbers to achieve a pre-determined result. In their paper, Usselman and Watson reported the results of their reconstruction of Dalton's experiments and provided an interpretation of the results on the basis of current chemical theory.

Although the equilibrium concentrations of the reactant and product gases over water are such that oxygen can be made to react entirely with twice its volume of nitrous gas to form nitric acid, theory suggests it is not possible to isolate the reaction in which oxygen reacts with four times its volume of nitrous gas. Replication of Dalton's 'narrow tube' experiment does not yield the expected 1:2 ratio but instead gives Dalton's reported 1:1.8 ratio. This result can be explained by the participation of oxygen dissolved in the water used as a seal for the gaseous reaction. The 1:3.6 combining gas ratio can then be achieved by using larger volumes of water, as Dalton did in his 'wide vessel' experiment. These results lead to the conclusion that i) Dalton obtained his published results by honestly reported experiments, ii) the results are replicable if the experiments are reproduced exactly as described, iii) modern theoretical interpretations of past experiments are not valid unless all relevant experimental parameters are considered and, most importantly, iv) Dalton did not falsify or misreport his results on the combination of nitrous gas with oxygen. This investigation suggests that careful reconstruction of scientific experiments can provide historical insights not possible by other historical methods.

John Hudson concluded the meeting with a short paper on "Dalton's Lakeland Excursions". Dr Sydney Ross, who was to have given a paper on this topic, was unable to attend. Hudson's paper described how after his move to Manchester, Dalton was in the habit of returning to his native Lakeland for a short vacation most years. As Dalton himself said he used these holidays to 'unite instruction with amusement'; i.e. he took the opportunity to make scientific, and especially meteorological, observations. He ascended Helvellyn over 40 times, but as he said 'most, or all, of the other high mountains in the vicinity have occasionally served my purpose'. Dalton had a portable barometer which he took with him on some of his ascents, and he usually measured the dew point and temperature at intervals. He carried a telescope with him, and on one occasion he hired a pony to take a large theodolite to the top of Helvellyn. However mountain walking was not the only activity. On one occasion, he and his companion Jonathan Otley went fishing from a boat on Derwentwater, but they took the opportunity to collect samples of gas from a submerged decomposing mass of peat. Dalton subsequently analysed the gas, and found it to be half carburetted hydrogen (methane) and half azote (nitrogen), with a trace of carbonic acid gas (carbon dioxide).

To date most of our information concerning Dalton's Lakeland Excursions has come from the account in William Charles Henry's biography of Dalton, published in 1854. However three letters written by Dalton in the years 1827, 1828, and 1829 to John Fletcher, his former teacher at Pardshaw school, and currently in Dr Ross's possession, were published for the first time by Dr Ross in 1999. These letters contain Dalton's own account of his vacations in those years, and give a vivid impression of energy and enthusiasm with which he undertook his trips. On one day in 1828 he accomplished a 14½ hour day to be followed the next day by a trip to the top of Helvellyn from Keswick – a round trip of 11 miles with 2850 feet of ascent and descent. Dalton was 62 years old, and was still evidently a fit man.

Dalton's ties to his native Lakeland were always strong. It was in the countryside of Cumberland and Westmorland that he made his first scientific observations, and until he became frail he returned almost every year both for relaxation and to carry out scientific observations. Dalton is rightly remembered as a Manchester man, but a study of his Lakeland excursions helps to emphasis that he was also a Lakeland man.

John Hudson