BIOGRAPHICAL MEMOIRS

Ian William Wark 1899-1985

This memoir was originally published in Historical Records of Australian Science, vol.6, no.4, 1987.

Introduction

When Sir Ian William Wark died on 20 April 1985, just 18 days before his 86th birthday, Australia lost one of its most influential scientists. He was born on 8 May 1899 at Spottiswood (now Spotswood), a Melbourne surburb, the second child of William John and Florence Emily (née Palmer) Wark. William John Wark (1868-1925) had been a student at Glasgow Technical College and had won an engineering scholarship to the University of Glasgow, but migration to Australia in 1884 with his widowed mother and younger brother had intervened. On arrival in Australia he was employed in a firm of agricultural implement makers, Hugh Lennon & Co, established by his mother's brother-in-law. In 1894 he married Florence Emily Palmer, who had however adopted her stepfather's name, Walton. Her husband left the Lennon employ and became a sub-agent for a life insurance company. This venture continued throughout his life with varied success; it led to the family living for short periods in Spottiswood, Hobart, South Melbourne, Sydney, Deepdene and Middle Park, and to the need to supplement the income to provide the necessities of life at a reasonable level. Ian Wark was the second child and elder boy in a family of four, namely Jean, Ian, Margaret and Donald. Donald studied agricultural science, carried out research in plant genetics for CSIRO and was made a Fellow of the Australian Institute of Agricultural Science for his work. Ian Wark's mother (Mrs W.J. Wark) lived to 93 years of age.

Ian Wark married Elsie Evelyn Booth, one of his former students from the University of Sydney, on 27 May 1927. Lady Wark died during the preparation of this memoir on 29 January 1987 at the age of 80 years. She is survived by a daughter, Elizabeth Helen (Mrs K.W. Stedwell), and three grandchildren.

Early schooling and university career

Ian Wark, in his own words, 'took to school like a duck to water' and in the first year of existence of the Melbourne Junior Technical School found himself dux with an offer of a scholarship to the Working Men's College (now RMIT). However, his father discussed Ian' s future with a leading consulting chemist, and ultimately Ian was enrolled at Scotch College. Although this was clearly a burden on the family finances it enabled Wark to enjoy four years at public school, where the influence of W.S. Littlejohn, the headmaster, and W.R. Jamieson, undoubtedly the doyen of chemistry masters of the period, encouraged his interest in and flair for mathematics and science. He was dux of the school in his final two years (1915/16). A major residential scholarship to Ormond College and exhibitions acquired at the final public examinations allowed him to live at Ormond College for the four years that he was studying at the University of Melbourne. On advice from various quarters, Wark entered first-year engineering, even though he felt that science was more to his taste. Fortunately, a medical problem that turned out to be transient rather than permanent prompted the family doctor to propose a change to science. Competing interests in mathematics, chemistry and physics proved more difficult to resolve. The professors in each of these departments were distinguished scholars and Wark was obtaining outstanding results in each subject. After a little indecision the influence of Orme Masson, the professor of chemistry of the day, won through, although J.H. Michell expressed his disappointment that a career in mathematics had been passed up. Wark was almost financially independent throughout his university career by winning exhibitions in many subjects. It is an interesting commentary on the period that the better students, who did not have the financial backing of affluent families, cold-bloodedly planned courses to maximize the financial return from exhibitions. In his first year he had to settle for shared exhibitions with Frank Macfarlane Burnet, later to become Nobel Laureate in medicine and President of the Australian Academy of Science. A good scholarship at the end of the third year (1919) allowed Wark to proceed to a fourth (MSc) year and to his first research topic. Masson, who many years earlier had studied several complex salts described as 'cupritartrates', suggested a research topic in this field, which Wark and J. Packer (later professor of chemistry in Christchurch, NZ) pursued jointly. The successful completion of the Master's degree at the end of 1920 really marked the completion of the formal training available for a career in science in Australia, since there was no PhD degree in Australian universities at that time. Wark had been outstandingly successful, although he had taken more than a passing interest in sporting activities – athletics, tennis, billiards – and in the countryside, in art, music, and literature. To someone of lesser capabilities these would have constituted distractions from the prosecution of a proper development of intellectual talents, but this did not turn out to be the case. Throughout his life Wark was almost insensitive to his surroundings when occupied with something, whether it be a scientific or administrative problem, writing, or lining up a golf shot. His powers of concentration allowed him to make more efficient use of his time and talents than most of us.

Post-graduate years

H.W. (later Sir Herbert) Gepp and A.C.D. (later Sir David) Rivett had both been involved in munitions production during the First World War in the UK and both had returned to Australia immediately on the conclusion of hostilities. Gepp, who was a metallurgical engineer without formal qualifications but with wide experience in the chemical and metallurgical industries and in mining, had been appointed general manager of the Electrolytic Zinc Company of Australasia Ltd. Rivett had returned to his post as senior lecturer in the Chemistry Department at the University of Melbourne and recommended Wark on completion of his MSc for a position in E.Z.'s South Melbourne laboratory. Gepp assigned to Wark a research project on the roasting of zinc blende. Not long after taking up these duties Orme Masson suggested that Wark apply for an Exhibition of 1851 Science Research Scholarship. The application was successful and Gepp released Wark without impediment. This was not to be the end of Wark's association with the E.Z. Co and the mining industry; several years later Wark was to find himself committed to a most fruitful period of scientific research for the mining industry.

In 1919, in Cambridge, F.W. Aston had devised the first mass spectrograph for study of the isotopic constitutions of the chemical elements. Wark, on Masson's advice, elected to take his 1851 Exhibition Scholarship at University College London, and to undertake research in the infant field of mass spectrography under the distinguished physical chemist F.G. Donnan. Essential equipment for this research, to be provided by the firm Brunner, Mond and Co, failed to materialize during Wark's two-year stay at University College so, as an extension of his MSc research, he made initially a study of copper malic acid complexes as a stop-gap and finally a study of a series of copper hydroxy-acid complexes as the total research project. This was a successful piece of research and established a long-standing interest and activity in this field. It is highly probable that this failure of Brunner, Mond & Co to supply the mass spectrographic equipment changed the course of Wark's research career. As it was, the essentially chemical rather than chemico-physical type of scientific work became his field of endeavour.

In former days, rather more so than now, the overseas research scholarship was the privilege of the very few outstanding students. The experience not only provided a perspective for Australian science (and one's own efforts) in the world scene, but gave the fortunate recipient a breadth of interest and understanding of world activity and affairs that had a dramatic influence on his future. This was certainly so in Wark's case. He travelled in Europe, took an active role in college sport and society activities, attended meetings of relevant learned societies, developed his cultural interests, took courses in physiology, German and eugenics, and spent some weeks in W.H. Bragg's X-ray laboratory as part of the broader educational process.

The 1851 Exhibition Commissioners granted Wark an extension of his scholarship for a third year, which he had planned to spend with H.R. Kruyt in Holland until a discussion with G.N. Lewis diverted him to Berkeley, California. His work in Berkeley with A. Olsen on ionization potentials of gases did not lead to publishable results, but he made the most of his close association with thermodynamics and low-temperature studies in Lewis's department and of his visits to other parts of the USA during vacations.

On his return to Australia during 1924, Wark's preparation for a career in the scientific field was complete. He was confronted with a choice between a position in an established chemical consultant's firm in Melbourne and a lectureship in the Chemistry Department of the University of Sydney. He chose the latter, probably because he saw his future in an academic environment. In those days the inorganic and physical side of the Sydney chemistry department boasted little by way of research activity, except for G.J. Burrows who was working in the coordination chemistry field. Wark and Burrows collaborated in work on the salicylic acid complexes of aluminium. After a year in this position it was with some relief that Wark accepted an offer from E.Z. Co Ltd to engage in full-time research on its behalf in Melbourne, particularly as his father's death during 1925 had created some new family responsibilities for him as the elder son.

Wark's return to Melbourne really marks the start of his significant scientific and professional career. His association with E.Z. Co and later with a group of mining companies gave him the opportunity to tackle several major technical problems in industry in an academic environment and in a reasonably long-term scientific manner without the pressures inherent in close associations with the production plant, which inevitably leads to an ad hoc approach rather than proper research investigation. It also gave him an insight into and led to a life-long interest in the mining, metallurgical and mineral industries. Coincidentally, it alerted Wark to the major role that personal relationships and jealousies can play in the conduct of professional and business activities. In fact, the three years spent with the E.Z. Co (1926-29) were an invaluable introduction to the real industrial world. H.W. Gepp, who was general manager of E.Z. Co and located in Melbourne, appointed Wark to act in a liaison capacity between Sir David Masson, whom Gepp had retained as a consultant, and the research department at E.Z.'s Risdon plant. Unfortunately, the general superintendent of Risdon had not been consulted and Wark found himself, through no fault of his own, the object of a rather unpleasant internal dispute. The one propitious outcome of the dispute was that Gepp established Wark and his assistants in a laboratory rented from the Chemistry Department of the University of Melbourne, in which environment Wark was to do the scientific work that earned him international repute.

Although the work on the physical and chemical principles underlying the electrodeposition of zinc was important to the company and was of a highly original nature, company policy precluded publication and it was not until 1964 that the company allowed publication of one aspect of the work. Gepp left the company in 1929 with the inevitable result that the research into electrodeposition ceased. H. Hey, who at the time was chief metallurgist with the E.Z. Co, came to the rescue with the proposition that Wark should switch over to mineral flotation research under his general direction but supported financially by a consortium of mining companies, namely, Zinc Corporation Ltd, Broken Hill South Ltd, North Broken Hill Ltd, Mount Lyell Mining and Railway Co Ltd, Burma Corporation Ltd and Electrolytic Zinc Co of Australia Ltd. The mining companies of Broken Hill had pioneered the use of flotation (particularly differential flotation) processes in ore-dressing and had accumulated much practical experience without a great deal of scientific understanding of why or how the process worked. It was to their credit – or perhaps to Hey's persuasive powers – that they were prepared to support, albeit at a very low level, fundamental research into the scientific principles underlying the flotation process. The companies continued support of this work until 1939, when Wark joined CSIR to establish research activity in chemistry for the benefit of Australian industry. E.J. Hartung, who followed Rivett as professor of chemistry in the University of Melbourne in 1928, also continued to provide laboratory accommodation for Wark and his assistants and made it possible for Mrs Elsie Wark, a science graduate from Sydney whom he had married during 1927, to work on the more academic aspects of Wark's research topics through the provision of occasional research grants. On his appointment to CSIR, Wark's personal research career virtually ended; the research in this field was continued in the Physical Chemistry Section of the new CSIR Division of Industrial Chemistry under K.L. Sutherland, who had been Wark's research assistant from the beginning of 1937. Wark's international scientific reputation rests exclusively on the research in mineral flotation and surface chemistry conducted during the period 1929-39. That this work was immediately successful and so consistently productive was quite remarkable; Wark had only one research assistant provided by the mining companies (A.B. Cox 1929-36 K.L. Sutherland 1937-39) together with help from his wife. The accommodation, which served as office and laboratory, was simply appalling; in these days it would have been condemned on health, safety and many other grounds. No present-day researcher would have considered accepting a job that required operating alone in such a laboratory, yet three people used it as office, laboratory and store-room for more than 10 years.

Wark's scientific research

Wark's scientific research can be classified conveniently under the heads:

  1. metallic hydroxy-acid complexes;

  2. electrochemistry, particularly the electrodeposition of zinc;

  3. physics and chemistry of the mineral flotation process and related surface chemistry;

  4. miscellaneous studies, mostly stimulated by work on the three topics listed above.

His first contribution to the scientific literature was an account with J. Packer of their joint MSc project. The second, however, was a letter to Nature on 'Energy changes involved in transmutation'. Evidently there had been some discussion of the possibility of the transmutability of sensible amounts of one element into others, but the accompanying energy changes had been ignored even though the liberation of energy had been established as a concomitant of the radioactive break-down of a nucleus. Wark examined the consequences of this 'should it ever become possible to control the breaking up of elements', one of which was that the availability of this intra-atomic energy 'should provide a satisfactory solution to the problems raised by the world's dwindling sources of power'. He also examined the consequences of the uncontrolled release of nuclear energy, describing a runaway 'chain' reaction (the word had not been invented in 1922) and commented 'the world might be reduced by some enterprising chemist or physicist to a white-hot nebulous mass'. This short communication may not be a contribution to original research but it demonstrates a maturity of thought well beyond that normally expected in a 22-year-old PhD student. The letter could well have been written twenty years later.

Constitution of metal organic hydroxy-acid complexes

The suppression of the reactions of heavy metals by organic hydroxy acids, such as tartaric and citric acids, had been the subject of investigation since the 19th century. The intensely blue alkali copper tartrate solutions had attracted much attention, particularly since Fehling's solution was a reagent of some analytical importance at the time. By 1920 the complex ion constitution was still unresolved, even though numerous compounds had been isolated and analysed. Masson had published a paper on the subject in 1899 and still wished to see the problem solved, so he set Packer and Wark the problem as an MSc research project. The resulting publication described the preparation and analysis of a number of crystalline neutral and alkaline cupritartrates, and established the stoichiometry and the fact that the copper atoms were incorporated in the anions. Since solutions of the neutral sodium salt did not oxidize glucose, but the alkaline sodium salts did, they concluded that the active principle of Fehling's solution would contain one or more of the complex anions of these salts. The paper also served to demonstrate that the structure of such complex anions would not readily be revealed by studies of salts of the relatively complicated dibasic dihydroxy acids such as tartaric.

As mentioned earlier, delays in the provision of a major piece of equipment for his intended PhD programme at University College, London, resulted in Wark pursuing, first as a stop-gap and then as a total programme, the further study of metallic hydroxy-acid complexes. Acting on his conclusion that simpler hydroxy acids would prove more tractable than the dibasic dihydroxy acids such as tartaric, he turned his attention to compounds formed with lactic and malic acids. He did not succeed in isolating any pure solid compounds from reactions between sodium hydroxide and copper lactate, but was able to establish the presence of a complex copper-containing anion in alkaline solutions containing excess sodium lactate by using the Nernst formula to obtain the Cu2+ ion concentration from single electrode potential measurements. Malic acid was much more productive; Wark isolated and characterized a number of salts of cuprimalic acid, and demonstrated by Masson's electrolytic method that the copper was present in the anion in alkaline solutions of cupric malate. At this stage the structure of the anion was still an open question, but a great deal of chemistry had been tidied up.

While at the University of California, at Berkeley, Wark was able to establish that the monobasic monohydroxy acids, lactic, mandelic, glycollic and salicylic, gave rise to similar copper-containing complex acids and was able to isolate the sodium salts of these acids from alcoholic solutions. It was clear that the hydroxy group was acidic and that it was the point of attachment of the cupric ions in all complexes with these four hydroxy acids.

Even as late as 1929 the existence of alpha-cupritartrates was being denied by two European chemists, who contended that the alkaline solutions were colloidal suspensions of copper hydroxide in neutral or alkaline tartrate solutions. By this time Mrs Wark was working with her husband in the Chemistry Department of the University of Melbourne, supported by research grants, and they carried out significant studies on these complexes. By using the technique of potentiometric titration, it was established that, at a NaOH/Cu molar ratio of 5/4, the e.m.f. of the hydrogen electrode rose sharply, indicating the onset of complex formation by analogy with similar behaviour observed with the monobasic monohydroxy acids. Studies of the Zn and Pb complexes of the monobasic monohydroxy acids with a view to preparation of alkaloid salts for optical resolution studies and of the stability constants of some 3-valent metal complexes of tartaric acid completed this series of investigations.

An isolated paper on aluminium salicylic acid complexes resulting from a brief collaboration with G.J. Burrows in Sydney described some new compounds, but the study was inconclusive as an attempt to resolve the structural problem.

The research in the field of metallic hydroxy-acid complexes was extraordinarily painstaking, meticulous and in the pattern of much of the chemical research of the day into the nature of complex molecules and ions. The work added careful information on the properties of these particular hydroxy-acid complexes to the store of chemical knowledge, but it did not resolve the original question of the structure of the complex cupri-alpha-hydroxy-acid ion. It was a well-executed academic chemical study, but the conclusion that the bases of the complexes were 5-membered rings, while certainly correct, could not be established unequivocally at that time, even though the existence of complex anions of this class in the monobasic monohydroxy acids, mandelic and salicylic, left little alternative to this structure.

Studies on the electrodeposition of zinc

The period 1926-29 immediately on his return from Sydney was spent by Wark in research on the physical and chemical basis of the electrodeposition of zinc from solution. H.W. Gepp, general manager of the Electrolytic Zinc Co of Australasia, had appointed Sir David Orme Masson, then Emeritus Professor of Chemistry in the University of Melbourne, as consultant; Wark carried out his research under Masson's general direction and had as successive co-workers E.E. Jones, metallurgist/electrical engineer with extensive experience of the Risdon process for 6 months, and H.P. Matthews, a metallurgist/chemist from the Port Pirie works of the Broken Hill Associated Smelters Pty Ltd (BHAS). Wark considered this to be one of the most productive periods of his life. Unfortunately, company policy precluded publication, so that the comprehensive report (235pp. of single-spaced quarto typewriting) on his three years' research, together with proposals for further work, is still not published. One must judge the quality of the work on his publications on peripheral matters and on two substantial papers published respectively 35 years and 50 years later with permission of the E.Z. Company. The fact that research results can still command journal space as original work 50 years after completion speaks volumes for the quality of the research and for the security of information within the metallurgical industry.

The first two papers are improvements in method and apparatus, the first concerned with a more rapid procedure for the calibration of conductivity apparatus and the second with a much more accurate procedure for the use of a copper coulometer following investigation of the causes of error under a wide variety of conditions of use.

The main purpose of this research programme, however, was to try to obtain a better understanding of the physics and chemistry of the electrodeposition process without involvement in actual plant trials. Cobalt, derived from the Broken Hill ore and always a minor constituent of the Risdon circuit liquors, was known to have a deleterious effect on the current efficiency of the zinc deposition process; the understanding of the way in which cobalt affected the electrolytic process was a major goal of the research. As a starting point, Wark made a careful investigation of the electrolysis of extremely pure zinc sulfate solutions. Plant practice had established that current efficiency (percentage of total current used in depositing zinc metal) decreased with time from the start of electrodeposition and that the addition of glue to the electrolyte greatly decreased the deterioration with time. However, in pure solutions Wark found that the current efficiency was constant with respect to time, current density and temperature and that glue and other colloidal solutions were unnecessary. He also made one important observation, that the current efficiency was determined by the ratio of the molar concentrations of Zn2+ and H+. The formalized expression of this relationship was discovered during 1926-29, published in 1964, and is now referred to as Wark's Rule. The next step was to study the effects of small concentrations of added cobalt sulfate on the current efficiency. A series of experiments studying the effects of temperature, acidity, current density and glue addition at various cobalt concentrations showed that Wark' s Rule applied at the start of the electrolysis. However, as time passed the current efficiency fell dramatically, although the effect was counteracted to some extent by higher current densities and higher rates of addition of glue to the electrolyte. The deterioration in current efficiency, that is, reduction in the electrodeposition of zinc, was considered by Wark to originate in the lower hydrogen overvoltage of the cobalt deposited with the zinc on the cathode than that of zinc itself. This results in a local couple, zinc is dissolved, exposing more cobalt and re-solution of the zinc proceeds autocatalytically. Wark demonstrated that all the results on the time dependence of the current efficiency fitted excellently the mathematical expression of this autocatalytic reaction. However, no more detailed mechanism for the effect of cobalt has been advanced. In the second papers published in 1979, when Wark was 80 years of age, the data accumulated 50 years previously was used to refute the view that 100% current efficiency would be attainable if the electrolyte solutions were absolutely free of impurities. Actually, a current efficiency of 100% is the unattainable limiting value at zero acid concentration, as expressed by Wark's Rule.

Surface chemistry and flotation

The concentration of ore by flotation had been achieved commercially in Australia in 1904 and by differential flotation in 1912. By 1927 there was a wealth of experience of the process among Australian metallurgists and mining engineers, but little understanding of the scientific basis for its successful operation. Overseas, particularly in American institutions, there had been a substantial amount of investigation, but experimental studies were plagued by irreproducibility and many theories of flotation existed. Many investigators had attempted to use the contact angle between an air bubble and a mineral surface as a measure of the adhesion between the mineral and air, and excellent apparatus had been developed for the measurement. However, the uncertainties in the experimental results and the inadequacies in interpretation meant that the understanding was still elementary and confused. It was at this point that Wark entered the field with A.B. Cox as his research assistant and decided to measure contact angles with apparatus based on the bubble machine developed by A.F. Taggart and his collaborators in the USA.

The initial study was directed at the role of collectors, reagents that promote contact between an air bubble and a mineral surface and so achieve flotability. The collectors chosen for study were the soluble xanthates and the minerals were those of significance in the Broken Hill ore bodies. Meticulous attention was paid to the reliability of the experimental method, to the purification of all reagents and to the method of preparing uncontaminated mineral surfaces that gave quantitatively reproducible results. The effects of activators and other modifiers used for changing the contact angle of a mineral surface were studied exhaustively. The presentation of the results of this work to a meeting of the American Institute of Mining and Metallurgical Engineers in February 1932 had an immediate and dramatic impact. Up to this time there was a great deal of inconsistency and disagreement in experimental results and very little agreement about the scientific basis of the flotation process. Suddenly, surfaces could be prepared that gave consistent results; experimental results started to make more theoretical sense; directions for further research were clearly indicated. In the discussion of this paper Professor A.M. Gaudin, one of the foremost authorities in the field of mineral flotation, commented:

From a scientific viewpoint few papers on flotation have been published that come up to the high standard of excellence attained by the contribution of Messrs. Wark and Cox. This memoir is definitely probing the realm of the unknown further into the distance, and indeed, marks a further step in the contribution to pure chemistry which the scientific phases of flotation are making.

Wark and Cox had established that if mineral surfaces were polished as for microscopic examination, but finally wiped on clean linen under water to remove adhering particles and slime, they would not make contact with an air bubble in distilled water. Of the sulfide minerals, some made contact with air when treated with a collector such as ethyl xanthate; others needed a preliminary treatment with an activator, such as copper sulphate for sphalerite, before an air-bubble contact could be achieved. The angle of contact, when achieved, turned out to be the same for all minerals and a particular xanthate; in an homologous series of xanthates the contact angle increased with increasing number of carbon atoms in the non-polar group. This constancy of the contact angle for a particular collecting agent for all sulfide surfaces indicates that the non-polar groups of the adsorbed collector molecules are oriented away from the mineral surface. Wark and Cox assumed that they were closely packed. A critical pH value, above which contact ceases and which varies with collector concentration, exists for each mineral/collector combination; this pH-concentration relation is called a 'contact curve' and is a useful device in designing or explaining selective flotation separations in practice. These curves were an important innovation in flotation research and were developed and used universally to great effect.

Subsequently Wark and Cox were able to demonstrate that these curves were lines of constant ratio of collector ions to hydroxyl ion concentrations and indicated competitive adsorption on the mineral surface as an explanation of this behaviour. The alkali, which interferes with the effectiveness of collectors for certain minerals, is representative of a class of chemicals known as depressants, to which cyanide and hydrosulfide ion also belong. This first paper was indeed a landmark in that it provided a satisfactory experimental method for studying the role of the various flotation reagents and the influence of these reagents on the behaviour of others, specifically the effect on the behaviour of collectors. In addition it provided satisfactory but fairly simple hypotheses of the way in which these various reagents worked.

Thereafter, in a series of papers with A.B. Cox, E.E. Wark and later K.L. Sutherland and J. Rogers, under the general title of 'Principles of Flotation' and published as Technical Publications of the American Institute of Mining and Metallurgical Engineers, the role of these reagents was investigated in meticulous detail and the 'contact curve' was developed as a meaningful expression of the influence of these various reagents on the essential interaction for flotation, namely, adhesion of an air bubble to the mineral surface. The practical incentive for these studies was the understanding of the conditions required for selective flotation and the ability to design processes for the selective separation of particular mixtures of minerals.

An enormous amount of reliable data was built up through painstaking experimental work and this demonstration of the power of the experimental methods stimulated much further work, particularly in the USA, Germany and Russia. The model of collector action – adsorption via the polar groups of the collector molecules on to the mineral surface in competition with other ions – was gradually consolidated and elaborated. The meaning of contact curves was gradually elucidated. With both cyanide and alkali present the adsorption of ethyl xanthate on the mineral surface depended on both pH and cyanide concentration. The contact curve was shown to be a line of constant CN- concentration, which indicates that a certain critical concentration of cyanide ion must be exceeded to prevent xanthate adsorption. Again one must assume competitive adsorption as the model. Exactly parallel behaviour was found when sodium sulfide was used as a depressant; the contact curve was found to be a line of constant hydrosulfide ion (SH-) concentration. With the further addition of copper sulfate, if it is required as an activator, the interpretation of the resulting contact curves is by no means simple, but the main effect is the reduction of the depressant function of cyanide by the removal of CN- ion in the formation of complex cupricyanide ions. Wark and Cox used the potential difference between a copper electrode immersed in a solution of known copper ion concentration and another copper electrode in a solution containing a copper salt with alkali and cyanide to determine the copper ion concentration in the latter. Because of the relationship between this e.m.f. and the copper ion concentration, lines of constant e.m.f. on the cyanide-pH diagram are lines of constant copper ion concentration. It was established experimentally in this work that the bubble contact curve for chalcopyrite was a curve of constant copper ion concentration (critical concentration). This experimental approach was rediscovered forty years later and used to good effect in modern flotation studies.

By the mid-1930s, the accumulation of reliable data on the interaction of flotation reagents and mineral surfaces had spawned an array of theories on the action of these reagents, specifically of collectors. Wark certainly favoured the surface adsorption model of collector action in which the collector molecules formed an oriented closely packed monomolecular film on the mineral surface. Taggart and his colleagues had provided a chemical theory of flotation that postulated the formation by double decomposition of insoluble metal xanthates on the mineral surface, a view that arose from the observation of a quantitative relationship between the insolubility of a heavy metal xanthate and adsorption of a xanthate film at the mineral surface (or the effectiveness of the reagent as a collector). Wark and Cox argued that the Taggart theory was untenable as a general model. Their paper is an excellent example of logical argument and contains the occasional touch of wit, such as: 'The behaviour of a naval rating on review is vastly different from his behaviour on leave. Likewise a lead ion held in its allotted place in the crystal lattice...cannot be expected to have the same characteristics as a lead ion free-swimming in solution.'

However, there were, even at that time, observations that fitted more easily into Taggart's model; surface-oxidized galena, which is the state of the mineral by the time it reaches the flotation cell, was a case in point. Much later work, namely, infra-red spectroscopic studies of oxidized lead sulfide films reacted with sodium ethyl xanthate and microcalorimetric studies of the reaction of galena and lead sulfate with xanthate, established without doubt that lead ethyl xanthate was formed on the mineral surface in the presence of ethyl xanthate collectors. In other sulfide minerals the presence of dixanthogen, produced by oxidation of the xanthate, was established as the collector, adsorbed presumably as a neutral molecule. Oxide and silicate minerals demand different considerations, as do the slightly soluble salt-type minerals, so that there is no universal model of collector interaction with mineral surfaces.

A rather less amicable atmosphere surrounded the arguments about the so-called adlineation theory of flotation proposed by Wolfgang Ostwald in 1932. The theory itself is no longer of any consequence, although it was certainly ingenious. Ostwald proposed that the collector molecules were adsorbed in a line or ring to the mineral surface at the point of attachment of the bubble, rather than across the complete surface. The theory required the collector molecules to have a triphyllic character, which most collector molecules do not have. However, Ostwald was a senior German chemist of international repute and at the time was editor of the prestigious journal, Kolloidzeitschrift. Wark had submitted to this journal a paper on the theory of flotation that was, in fact, a detailed criticism of Ostwald's theory. Ostwald refused to publish it, but after further representations an adjudicating panel of three senior German physical chemists recommended publication, but in Zeitschrift für physikalische Chemie. Ostwald's theory did not survive.

The final paper of this series with which A.B. Cox was associated explored the effects of temperature over the range 10°-35°C on the adsorption of xanthate collector and on the function of depressants and activators. The results were of some practical significance, but the lack of quantitative data on the reactions and equilibria involved frustrated any attempt to develop a detailed theory of the temperature effects.

The entry of K.L. Sutherland into the field, when Cox went to the Munitions Supply Laboratory, Maribyrnong, saw a new line of investigation emerge. The study of contact curves for the commercial flotation reagent Flotagen S (sodium mercaptobenzthiazole) under conditions of varying temperature, depressant and activator concentrations, for several sulfide minerals, threw up new features, specifically islands and peninsulas of non-contact in the region conventionally associated exclusively with contact. It was found that the island areas occurred only in liquor containing copper salts and were larger at lower temperatures, and that the contact diagram was different at different copper concentrations and for different anions present in the flotation liquor. The results of this first study were so unexpected that they demanded a reinvestigation of the xanthate contact curves under conditions where similar effects might be expected, namely, lower collector concentrations and temperatures. This study gave further clues to methods of increasing the differentiation between minerals in flotation practice using a single collector. The comprehensive study demonstrated the successive stages of departure from the standard type of contact diagram in copper-containing xanthate solutions through an isolated island of non-contact at around pH 7, to growth and merging of the island with the upper area of non-contact to form a peninsula, to very limited areas of contact at low cyanide concentrations. These effects were studied as a function of the xanthate concentration, the amount of copper salt, the temperature and the nature of the anions introduced in the copper salt, the alkali and other neutral salts on a variety of sulfide minerals. It was established that the islands of non-contact were associated with xanthate ion deficiency and consequent incomplete coverage of the mineral surface with adsorbed xanthate. The boundary of the islands is the locus of points of critical values of the ratio of xanthate ion to cyanide ion concentrations beyond which contact occurs.

In 1938 Wark and his wife began a study of the paraffin-chain salts, both cationic and anionic, as flotation agents. Wark's active participation with the experimental side of this research ended with his appointment to CSIR, but Sutherland continued the work at the University of Melbourne during 1940 and then incorporated it in the research programme of the Physical Chemistry Section, of which he had been appointed Leader, of the newly founded Division of Industrial Chemistry, of which Wark had been appointed Chief. Justification for the continuation of this research during the 1939-45 War lay in the fact that paraffin-chain salts had significance as potential flotation agents for certain strategic minerals, for example, cassiterite. The relevant paper was ultimately published in 1946. Whether the paraffin-chain salt be anionic (hydrocarbon-chain in the anion), such as soaps, alkyl sulfates etc, or cationic, such as alkyl ammonium chlorides, the molecular ions are of a polar-nonpolar character and are adsorbed on to appropriate surfaces as oriented mono-molecular layers in much the same way as xanthates. It is, of course, this property that confers on these compounds their potential as flotation collectors. As one might expect, the anionic compounds are generally useful for basic minerals, whereas the cationic compounds are more useful for acidic minerals. Specificity is not inherently very good, so this study was directed towards the establishment of flotation specificity by careful control of conditions determined by pH and depressant concentrations. The contact curves (concentration of collector versus pH or concentration of depressant versus pH at constant collector concentration) are quite different in type from those established for the xanthate collectors. The curves are typically enclosing areas of contact (or flotation) extending to low collector concentrations centred at pH values of about 7, with an upper limit at higher concentrations above which contact is impossible. This limiting concentration is of the same order as that at which micelle formation sets in, but the loss of contact is not due to this. Moreover, there is no prevention or reduction in the adsorption of collector on the mineral surface. Wark had earlier attributed this type of behaviour to 'armouring' of the bubble with oriented collector molecules that must be displaced from the bubble surface for true air contact with the mineral surface to be established. Subsequent research substantiated this theory of the upper contact limit. The basic principles and understanding established through this work led to selective flotation schemes for tin ores, fluorite and scheelite.

Parallel with this series of Technical Publications in which the emphasis was on the establishment of practical conditions for flotation, Wark and his collaborators published in the Journal of Physical Chemistry a separate series on the physical chemistry of flotation. They explored the physics and chemistry of the adsorption and interaction processes on which flotation depends in greater depth than the work directed to the establishment of the optimum conditions for a specific flotation process warranted. Here again the first paper of the series, published in 1932, was by far the most significant and established the contact angle as an appropriate measurable physical quantity on which to base flotability. Wark treated the problem of the adhesion between a bubble of air and a single solid particle and the way in which this depends on the contact angle q, which in itself is related to the three interfacial tensions in

cos q = (Tas – Tsw)/Twa.

Starting from the Bashforth and Adams classical treatment of the shape and size of bubbles, Wark derived relationships between volume of bubble, circle of contact of bubble with particle surface, and contact angle. He computed sets of curves for the relationships between each pair of variables for constant values of the third variable. The relationship between maximum values of bubble volume and radius of circle of contact and contact angle were confirmed quantitatively by experimental measurements by Cox and later by Frumkin in the USSR. Wark also considered the problems of (i) hysteresis, that is, the difference in contact angles for advancing and receding lines of air-solid contact, (ii) the stability of attachment between particle and bubble in relative motion, and (iii) the maximum size of particle that will float; he discussed the significance of the findings in actual froth flotation. This paper, one of the few in which Wark displayed his training and undoubted ability in mathematics, clarified a confused literature on the essential prerequisites for successful flotation and provided a satisfying theoretical basis for subsequent experimental studies. In it, in a single paragraph, Wark also effectively demolished Ostwald's adlineation theory of flotation; however, as discussed earlier, it took several further papers to remove the theory from serious consideration by some workers in the field.

The majority of subsequent papers in this series were concerned with the nature of the adsorption of soluble collectors on mineral surfaces, unactivated and activated. Apart from the controversy with Ostwald over the adlineation theory, which has been dealt with earlier, these papers were concerned with differentiating between Taggart's chemical theory and adsorption. The studies were not conclusive; subsequent work showed that different mineral-collector combinations behave in quite different ways. However, the assumption that a complete coverage of the mineral surface was necessary before flotation could be achieved turned out to be grossly wrong. In fact, work in Wark's own laboratory, by G.R. Edwards and W.E. Ewers, and elsewhere showed that less than 10% coverage in many cases was sufficient to promote flotation. This problem is the subject of active study at the present time.

Wark maintained an active interest in this field until his death. He reviewed the outstanding problems of contact angle, adhesion and flotation in several publications and contributed some original concepts on the origin of hysteresis of contact angles in a paper in 1977. At the time of his death he was involved in a joint study aimed at the experimental confirmation of a thermodynamic hypothesis. The paper describing the subsequently completed investigation entitled 'Contact angle studies in water fluoroplastic systems – the effect of drop and bubble size' by R. Lamb, I.W. Wark and T.W. Healy has been accepted for publication in the Journal of Colloid and Interface Science.

Although Wark's period of active personal research in this field was ten years only, he influenced the subsequent research significantly. Not only did he remove uncertainties in the experimental results through devising and establishing impeccable techniques, he stimulated overseas investigators to pursue new research lines through his experimental results and his interpretation of them. Moreover, he established a major school of flotation research that has continued through its various offshoots to have a major impact on the development of the subject up to the present. The Wark Symposium on the Principles of Mineral Flotation held in his honour in 1983 provides ample testimony to his influence over 50 years of scientific investigation.

Wark's monograph, Principles of Flotation, published in 1938, and its revised edition (1955), written in collaboration with K.L. Sutherland, made immediate and sustained impact throughout the world. They became standard text-books and reference books on the subject for research workers and plant operators and were translated into Russian, Japanese and Turkish. Indeed, 'Their monograph Principles of Flotation...continues to be one of the most important reference books available to plant and research metallurgists in their efforts to solve the many problems still occurring in flotation' (A.J. Lynch, Principles of Mineral Flotation, The Wark Symposium [1984], p. 233).

From the time of publication of his first papers in the field, Wark was invited to lecture to institutions and learned societies on this work. Perhaps the key lectures were his Presidential Address to Section B of ANZAAS in 1946 and the contributions to the 4th European Mining and Metallurgical Congress in London in 1949, the 8th Commonwealth Mining and Metallurgical Congress in Australia and New Zealand in 1965 and the 5th Sir Julius Wernher Memorial Lecture of The Institution of Mining and Metallurgy in London in 1960. He lectured at various times to institutions in Russia and Japan, where his reputation was well established in the 1940s. Even as early as 1937, F.G. Donnan, Professor of Chemistry and Director of the Chemical Laboratories, University College, London, was able to write in a testimonial:

His researches on the extremely difficult subject of the theory of ore flotation are recognised now throughout the world as by far the finest work in this field. Indeed, I have heard several European experts state that his work is regarded as classical and of fundamental importance, both scientifically and practically.

The first papers in each of the two series of publications on flotation contained a view of the principles of flotation that did not change in any basic way during Wark's active research career in the field. In fact, the point of view in his paper to the 1983 symposium is much the same as that of 1932. It almost looks as though he made an intensive study of the literature on flotation, both principles and practice, decided what were the current theoretical problems and what experiments had to be done and, having done them, formulated a model of flotation that he would not abandon easily. This would certainly be in character; Wark did not easily change his mind when he had come to a conclusion based on what he considered to be sound reasoning.

Miscellaneous studies

Apart from the letter to Nature on the consequences of transmutation of the elements referred to earlier in the introductory remarks on Wark's scientific research, there is only one other research publication the origin of which cannot be attributed directly to one or other of the three main research topics of Wark's career, namely 'An extension of the conception of the distribution co-efficient'. Arguing from the similarity of the mathematical expressions for the pressure and temperature dependence of the distribution of a solute between two phases and of chemical equilibrium, Wark derived the basic equation for chemical equilibrium by treating the reacting system as a distribution problem. Wark was disappointed that this paper did not attract any attention, but it is difficult to see any conceptual or derivational advantages.

General assessment of research contribution

Wark's personal scientific reputation rests exclusively on his publications on mineral flotation. From the very outset his contributions demanded attention and prompted further research. His first two papers on the subject established a degree of order in a very confused field and provided methods through which reproducible results could be achieved. He certainly added new data and understanding to the progress of the subject and initiated new lines of attack, not by brilliant creative steps, but rather by impeccable experimental technique, meticulous attention to detail in operation and interpretation and by exploring exhaustively the consequences of change of every conceivable variable for the system. His approach was always logical, systematic, precise and exhaustive.

The CSIR/CSIRO period: Research direction and administration

Ian Wark's principal contribution to science and Australia was his creation and development of the CSIR/CSIRO Division of Industrial Chemistry. It was not by chance that Wark elected to major in chemistry rather than physics or mathematics, in which he seemed to be equally proficient if examination performance is any guide. He found that some of the staff of the Chemistry Department imbued in him an enthusiasm for the subject. Orme Masson was the professor of chemistry and a dominant individual, not only in chemistry in Australia but in science in general, in academic circles and in influence with the governments of the day. When Wark entered the University of Melbourne at the beginning of 1917 Masson was at the height of his powers and influence and was leading the move to establish a government-financed research facility directed to the solution of industrial problems and the promotion of new industrial enterprise. Masson' s protégé and next in seniority in the department, A.C.D. Rivett, returned to Melbourne from the UK, where he had been engaged in munitions production, at the beginning of 1919. Rivett arranged for Wark to be employed by E.Z. Co in 1920 and also initiated the research appointment to the same company in 1926, and provided laboratory accommodation in the Chemistry Department. Wark was to some extent a Rivett protégé and had adequate opportunity to promote to Rivett the need for chemical and metallurgical research for industry. By the mid-1930s Wark had become dedicated to the mineral industries and retained this inclination throughout his life. Although from the time of the original legislation in 1917-18 for the establishment of CSIR's predecessor, the Institute of Science and Industry, the first power and function cited for the organization had been 'the initiation and carrying out of scientific researches in connexion with, or for the promotion of, primary or secondary industries in the Commonwealth', the economic depression of the late '20s and '30s had left CSIR with funds sufficient only for research in the most urgent aspects of problems in primary industry. Any positive moves towards research for secondary industry had had to be postponed. However, the threat of war stimulated consideration of the needs in this area and in 1937 a committee of the Commonwealth Government recommended the formation of a national standards laboratory, an information service, an aeronautical research laboratory and a chemical research laboratory. The first three were soon commenced, but it took the threat of imminent war to goad the CSIR to advertise for a Chief for a Division of Secondary Industry. Rivett virtually offered the job to Wark, but the CSIR Chairman, Sir George Julius, a down-to-earth engineer, began to propose compromise arrangements on the grounds of Wark's lack of experience outside a small research laboratory. Rivett finally won this battle but R.G. Casey, then the responsible Minister, postponed the establishment of the new Division. Rivett bided his time; after war had started he got approval to appoint Wark as Senior Chemist at £1,000 p.a. rather than Chief at £1,500 p.a. Together with E.J. Drake, who had been assigned as his assistant, Wark prepared a case for the establishment of a Division of Industrial Chemistry; this secured approval from Rivett and ultimately from the Minister, by now H.E. Holt, who obtained Cabinet authorization for its formation early in 1940. Rivett provided unqualified support for the projected development of the Division, both because it was his policy to give complete freedom of action to an appointee that he considered worthy of heading up a Division and because the wartime circumstances demanded immediate attention to a range of chemical problems. It was inevitable that rapid expansion of the Division should take place for a considerable time and yet provision of laboratory accommodation somehow did not rate top priority. For two years the Division operated from a nucleus in the CSIR Head Office building with temporary laboratory space in at least five other locations around Melbourne, before a building, still quite inadequate for the total staff and work even in 1942, was occupied at the Fishermen's Bend site. This situation still persists to some extent; until recently successive CSIRO Executives failed to give the proper accommodation of the chemical divisions adequate priority so as to solve the problem once and for all. However, the final laboratory building on the Clayton site could be occupied during 1987.

Wark set out to establish a Division of Industrial Chemistry whose objectives were:-

  1. to provide technical efficiency in established industries;

  2. to stimulate the establishment of new industries;

  3. to encourage the use of raw materials of Australian origin;

  4. to seek substitutes for imported materials;

  5. to find uses for by-products not utilized;

  6. to study national problems to which its officers can contribute by virtue of their experience in other fields.

The conventional structure for the research activity of CSIR Divisions was already established as a number of component Sections under research leaders. Wark proposed a mixture of Section names, some with disciplinary, others with commodity or industry titles, namely, Physical Chemistry; Organic Chemistry; Biochemistry; Chemical Engineering; Mineral Chemistry; Cement, Ceramics and Refractories; Dairy Research; Physical Metallurgy (jointly with the Division of Aeronautics); and later Chemical Physics and Foundry Sands. Initially, Wark made fairly detailed lists of projects, based largely on the perceived needs of existing industries and the immediate requirements for the prosecution of the recently declared war. The bias was fairly heavily towards the mining and mineral industries, partly because of their national importance and partly because Wark's own experience and interest lay in this field. As time passed, the programmes changed to reflect the interests and views of the Sections; each Section developed its own particular character, displayed through its philosophy, outlook and research activity.

Growth in staff numbers was steady in the post-war years, but the accommodation situation deteriorated dramatically. Wark gave strong support to proposals from the Section leaders that appealed to him, mainly through formal documentation and representations in person to Rivett and F.W.G. White, who had become the Assistant Executive Officer with responsibilities in the physical sciences area. Yet the acquisition of modern equipment and some staff growth completely outstripped the provision of accommodation, a situation which became steadily worse through the 1950s when a large proportion of the Division's research, involving a substantial amount of sophisticated equipment, was housed in converted disposal army huts and other makeshift accommodation. For the new chemical laboratory to reach such a state in ten years, there must have been deficiencies in the promotion of the capital works requirements at some level, even allowing for the fact that funds for these purposes were limited. Wark's approach, at this stage of his career, was perhaps too timid and relied too much on the presentation of an argued case on paper. In spite of this, the scientific output and reputation of the Division grew and recognition in international scientific and industrial circles was established early in the Division's life. This was undoubtedly due to Wark's acceptance and practice of Rivett's philosophy, namely, that the selection of staff was of paramount importance and that top-quality scientific staff could be left to tackle the problems for which they were appointed without interference.

Wark started the project of creating a national chemical laboratory with an outstanding academic background, an established reputation in the scientific principles of mineral flotation, a fairly widespread understanding of the chemical and mineral industries and virtually no experience in administering a large operation or handling a large staff. In spite of this latter deficiency and the problems arising from it, Wark created a research establishment of considerable stature. By 1958 the Division of Industrial Chemistry had developed to such an extent that the CSIRO Executive decided to reconstitute it as the Chemical Research Laboratories with Wark as the foundation Director and the constituent parts Divisions and Sections (later all became Divisions). This new group laboratory continued until 1970, but the nature of the administrative control changed in 1961, when Wark moved to the CSIRO Head Office as a member of the Executive. The story of Wark's achievements in the establishment and development of the Division of Industrial Chemistry has been recorded in greater detail elsewhere and need not be repeated here.

Wark's appointment to the CSIRO Executive in 1961 was not the first occasion in which he was considered for an Executive post. Rivett had been keen for him to apply for one of the Assistant Executive Officer positions that the Executive advertised in 1944; Wark had investigated the post but after due consideration did not lodge an application. Again, he was certainly considered seriously in exploratory discussions in 1949 on the retirement of Rivett and A.E.V. Richardson, when the Executive was reconstituted under the new Act with a full-time Chairman and two members; yet evidently he was not approached. During his term on the Executive he saw many changes in its composition and served a period as Acting Chairman. Wark did not really enjoy his period on the Executive but went about the job with characteristic dedication. He saw the nature of the Executive change – in his opinion not for the better – and supported a return to the three-man Executive. At the age of 65 years he declined appointment for a second term and moved with relief to the post of Chairman of the new Commonwealth Advisory Committee on Advanced Education.

It was at about this time that he wrote a book entitled Why Research? for a career series. He had made a lecture tour of New Zealand under the auspices of the University Grants Commission of New Zealand in 1962 and one of his lectures was subsequently published in Nature in 1963. As a result of this he was invited to write a book for secondary school students by the English publishers, Educational Explorers Limited. The book, published in 1968, was to some extent autobiographical and enjoyed a reasonable sales success.

Promotion of tertiary education

During his time on the CSIRO Executive, Wark had occasion to establish close relations with J.G. Gorton, at that time Minister in charge of Commonwealth Activities in Education and Research. Hence it was no surprise, when the Commonwealth Government decided to set up a new Advisory Committee on Advanced Education in 1965, that Wark was appointed its first Chairman. During the previous ten years, successive governments had enquired into the state of education in Australia and had recognized the deplorable state of university accommodation, facilities and funding. Corrective measures taken through the establishment of a Universities Commission were having recognizable effects by the early 1960s. However, a further enquiry into tertiary education under the Chairman of the Universities Commission, Sir Leslie Martin, urged the development of the non-university tertiary stream, which in 1962 was attracting only 7% of the total money available for tertiary education even though it represented 37% of total tertiary students. The function of Wark's committee was, through advice to the Minister, to promote the 'balanced development of tertiary education outside the university system', in particular 'in connection with grants for capital and recurrent purposes' to Commonwealth and State institutions other than universities for teaching at the advanced education level.

Wark was able to channel funds into the Colleges of Advanced Education (CAE) system and encourage the States to make special provision for the tertiary colleges over the period of his chairmanship from 1965 to 1971. Dramatic changes were evident early in this period, but the transformation was not without its problems. Wark's advice to the Minister during the development of the Commonwealth's policies on tertiary education had a considerable influence on the CAE sector. Some of the policies adopted by the Wark Committee were not helpful where States were attempting to ensure that CAE courses and the resulting awards were at a standard equivalent to those at universities already accepted by professional and employing bodies. The award of bachelor's degrees by the CAEs was opposed at first; the various States went ahead, but with suitable controls. Later moves into the area of higher degrees by research were opposed even though the policies had been developed and justified in great detail. Again the States went ahead with very successful higher-degree programmes, but without funding support. Even in the late '70s the Commonwealth was still giving lukewarm approval only to Master's degrees by research in the CAE system, preferring Master's programmes based on course work.

Although he had been located in a university department for the duration of his active research career, Wark had had no direct involvement with tertiary education prior to 1965. He had, however, definite ideas about tertiary education and throughout his term on the Council of the Australian Academy of Science contributed a great deal towards stimulating the government to look carefully at the problems of scientific manpower and funding of university research. Clearly he had thought deeply about the problems and had formulated a personal educational philosophy. Up to 1965 he had not made a public statement, either oral or written, on education matters, but from the time of his appointment as Chairman of the Advisory Committee he gave many addresses and wrote many articles on the problems of advanced education. His influence on the development of the CAE sector was very great; the tertiary colleges throughout Australia should all be very grateful to him.

The following extract from the citation at the conferring of the degree of Doctor of Arts and Sciences (honoris causa) of the Victoria Institute of Colleges on Sir Ian Wark on 8 May 1979 is an excellent statement of his contribution:

The years 1965 to 1971 were tumultuous. They were marked by a rate and scale of development, both quantitative and qualitative, which have few parallels in our education history. As Chairman of the CACAE, Sir Ian oversaw, encouraged and supported the creation and development of over fifty colleges of advanced education in all States of the Commonwealth. In close partnership with State authorities, of which the VIC was proudly one, Sir Ian helped to transform tertiary education in Australia. His vision, courage, leadership and extraordinary and diverse skills were profoundly important in the process of creating colleges of advanced education as they now are out of a relatively small number of technical and other specialised colleges which were desperately lacking in the tangible and intangible resources essential for a healthy institution. The high academic and professional standing of advanced education awards and the complete recognition of college graduates is testament to Sir Ian's pioneering work...There can be few men who have made so great a contribution to Australia in science, administration and education as Sir Ian Wark.

He continued his association with the college sector for some years (1971-77) after his retirement from the Advisory Committee, as a member of the South Australian Board of Advanced Education.

Extra-mural activities

Association with learned societies

Perhaps Ian Wark's outstanding characteristic was his inability to do nothing. His life was filled with purposeful activity; his off-duty hours were devoted to matters of professional, scientific or public interest or to leisure interests, both sporting and cultural, to which he gave the same concentration to achieve the maximum contribution of which he was capable.

Wark became actively involved in learned and professional bodies concerned with chemistry from the time of his graduation. His first and main affiliation was to the recently established (1917) Australian Chemical Institute (now the Royal Australian Chemical Institute); he became an Associate member in 1921. Together with the local Melbourne University Chemical Society, the Chemical Institute provided a continuing forum for meeting with other chemists and lecturing on his own topics throughout his life. He contributed to the development of the Institute in many ways, serving as the Victorian Branch President in 1942 and 1943, as Federal President in 1958 and as the inaugural President of its Colloid and Surface Chemistry Division in 1978. He was honoured by the Institute by the award of the H.G. Smith Medal for his scientific research in 1933 and the Leighton Memorial Medal in 1966.

The other major body catering for chemistry was the Australian and New Zealand Association for the Advancement of Science (ANZAAS). Wark became involved early in his career, becoming a Fellow in 1946 and as such a member of the Australian National Research Council (ANRC), which was comprised of the Australian Fellows of ANZAAS. It was as a member of ANRC that he became convener of the National Committee for Chemistry, the body that maintained links with the International Union of Pure and Applied Chemistry until the creation of the Australian Academy of Science in 1954. Wark served as a Vice-President of Section B (Chemistry) of ANZAAS on several occasions and Section President at the Adelaide Congress in 1946. He was awarded the ANZAAS Medal in 1973.

The research on the mineral flotation process led to many calls for Wark to lecture to societies of a more applied character, particularly those associated with the mining and metallurgical industries. He was very highly regarded in these quarters; in fact, the Australasian Institute of Mining and Metallurgy was the publisher of his Principles of Flotation in 1938 and its revised version with K.L. Sutherland in 1955. He was elected to Honorary Membership of the Australasian Institute of Mining and Metallurgy in 1960.

By the time the Australian Academy of Science was founded in 1954, Wark had become actively interested in the more general problems of science – its promotion, its impact on the community, its place in education, its contribution to industrial and economic welfare. He was elected a Fellow (FAA) in 1954 in the group required by the Charter to be added to the Petitioners before 15 May to bring the Fellowship numbers to 50 at least. From that point on, he contributed actively and constructively to a wide range of Academy concerns and was elected a member of Council in 1959 and Treasurer for the period August 1959 to 1963. One of the early concerns of the Council and Fellowship was the adequacy or otherwise of the nation's scientific manpower. After discussion at the first General Meeting in November 1954 and at the first Annual General Meeting in 1955, two Fellows from each State were asked to report on the problem as it affected their region and to make proposals for its correction. Discussion at the 1956 Annual General Meeting led to a conference of representatives of various institutions on 'Scientific Manpower' in Melbourne in November 1956. At the next Annual General Meeting, Wark proposed that the Academy should press for a full enquiry and Council asked him to prepare a report for submission to the government. While the government did not accept the proposal for an enquiry, the report certainly influenced its attitude to the importance of support for science and technology. Once he was elected to Council, Wark became even more active and influential in promoting proposals to the government for assistance in various ways – funds for research, post-doctoral fellowships – to promote the effectiveness of science and technology in national growth.

It was as Treasurer that Wark made his most valuable contribution to the Academy. The appeal for funds to cover the capital cost of the Academy's new building was greatly under-subscribed and it was evident that a major benefactor was needed. Through a friend of long standing, Wark identified J. Ellerton Becker as a prospect. With assistance from the President of the day, J.C. Eccles, and the Prime Minister, R.G. Menzies, Wark persuaded Becker to cover the building debt and to provide additional substantial funds to support Academy activities. He gained great satisfaction from the obvious pleasure that Becker and his wife derived from the Academy association; Becker became a Fellow by Special Election in 1961 and served on Council, 1965-68.

Wark was appointed a Governor (honorary) of the newly established Ian Potter Foundation in 1964 and remained so until his death. In this capacity he was able to find support for various scientific activities and in his last few years saw the Ian Potter Foundation contribute $250,000 to the cost of alterations to and refurbishment of Ian Potter House for the Academy.

Learned societies and applied science and technology

Perhaps Ian Wark's most enduring passion was his conviction that applied science was undervalued in scientific circles and that applied scientists were given inadequate recognition. The origin of this belief is somewhat surprising since he himself was by inclination and training an academic scientist, who by force of circumstance became an applied scientist, and who was recognized and acclaimed throughout the scientific community for his applied work. Be that as it may, there is no doubt that Wark was dedicated to the cause of applied science and influenced the course of events in Australia.

The debate, which centred mainly around the Academy, became a black-and-white issue; individuals were cast in one role or the other, in spite of the fact that different people did not agree on what constituted 'applied science' or how it related to 'technology'. It is perhaps significant that the Petitioners for the Charter founding the Academy included Essington Lewis and W.S. Robinson, two of Australia's leading industrialists, and that in the '50s and '60s the Academy's Regional Groups held frequent dinner meetings at which other leaders in industry, technology and business were present as guests and speakers.

At the time when Wark retired from Council in 1963, there was a body of opinion represented by a number of Fellows that closer relations should be established between the Academy and leaders of industry and government and other community leaders, in order to promote better understanding and better use of science. Wark was active in this move and participated in leading roles over the next two years (1964-66) in symposia organized to explore possible mechanisms for achieving the desired relationship between the Academy on the one hand and industry and government on the other. He also used his close relationship with Commonwealth and State Government leaders to promote his objectives. Meanwhile the Academy Council was struggling with the problem of the most appropriate form for the joint representative body and the means of financing it. The establishment of the Science and Industry Forum as a Standing Committee of the Academy on 7 December 1966 was a significant and highly successful decision. A factual account of this development, including Wark's part in it, is given in the Academy's publication The First Twenty-five Years (Chap. 13, pp.164-169).

The other aspect of this preoccupation with applied science concerned the election of applied scientists to the Fellowship of the Academy. The debate in Council and at General Meetings continued for many years, often stimulated or carried by Wark. Ultimately, this led to the establishment of the Australian Academy of Technological Sciences in 1976, the composition of which bears a resemblance to that of the ANRC, which voted itself out of existence on the formation of the Academy. Wark had a significant role in the foundation of the new Academy of Technological Sciences and became one of its foundation fellows.

Twilight years

Honorary consultancy

In 1971, at the age of 72 years, Ian Wark found himself without a full-time occupation, but was not prepared to retire. His lifelong involvement in and association with minerals research and the mineral industry was not to be left unused. I.E. Newnham, Director of the newly founded CSIRO Minerals Research Laboratories, invited Wark to become an Honorary Consultant to the group. This provided office accommodation and secretarial help at two locations, the Division of Mineral Chemistry at Garden City and the Division of Chemical Engineering at Clayton, between which, in spite of several nomenclature changes, Wark divided his time until his death. It is clear that he advised widely during these years, helped in some of the chores such as arranging seminar programmes, and committed much to paper. He even returned to one or two unresolved problems from his early research career, which resulted in a paper on the electrodeposition of zinc and three papers on problems in flotation research published in the late '70s and early '80s.

Personal records and documentation activities

Throughout his life Wark recorded diary notes. He kept his opinions and views on events and people on record; in fact, records, no longer extant, of every individual who had been employed, however briefly and at any level, within his CSIR/CSIRO bailiwick contained comments on their performance and personal qualities that would be dangerous in these days of freedom of information legislation. Wark continued to keep – perhaps unfortunately – detailed comments on people and events as he saw them, right to the end.

He spent a great deal of time from 1971 organizing his biographical material, writing accounts of various parts of his life, collecting together documents and personal papers. In fact, his biographer will have a remarkably easy task; all the necessary material is accessible and organized. The compilation of this biographical memoir would have been much more onerous without Wark's foresight in his retirement period.

Wark the man

It was clear from Ian Wark's schooldays that he was destined to make a significant contribution in whatever career he chose and that he had remarkable powers of concentration and a single-minded determination to succeed. Throughout life, he worked with great application and for long hours, but work was by no means his sole interest in life. He was fond of physical activity and had a better-than-average record in a number of sports. He played golf regularly and was an outstanding exponent of fly-fishing. It was typical of the man that he devised a trout fly which is still catalogued and sold as Dr Wark's Special throughout the world.

Wark had catholic tastes in music, literature and the arts and in latter years tried his hand at musical composition, a full-length play, a one-act thriller and some verse.

His accomplishments in his three major fields – research, research administration and education – remain tremendous and stamp him as a man of considerable stature and influence. He was aware of his successes and derived pleasure from the awards that flowed to him from learned societies, academic institutions and governments. Throughout it all he maintained his principles, his humanity and his friendliness.

As a person he was reserved to the point of being shy, particularly up to about 50 years of age, and at no stage did he become reconciled to clubs. On the other hand he enjoyed and relaxed in the company of people he knew well. To his staff he was always somewhat apart, even though he went to great lengths to establish democratic habits; only to some of his senior staff did he ever become close. These characteristics were probably ingrained from student and early post-graduate days in a generation where even senior lecturing staff of a university department addressed the professor by title throughout the whole of a career.

Wark was always very sure of the opinions he had formed, either on issues of consequence or on people. There was rarely any doubt in his own mind about the quality of the opinion; there were few grey areas. This may have been a refreshing characteristic in many circumstances, but the inflexibility to change or compromise was a fault. Once he had made a judgement of a person, either as scientist or administrator, he could not be influenced. Moreover, he did not like being crossed in a major way and did not find it easy to overlook the matter afterwards. In fact, it sometimes led to misunderstood records of subsequent events or discussions. However, one must not allow this evidence of human fault to diminish the consequences of the attainments of the man.

Honours and awards

Learned societies, professional bodies and academic institutions honoured Wark by awards of various kinds throughout his career. Imperial honours crowned his career, first by appointment as Commander of the Most Excellent Order of the British Empire (CBE) in 1964, then appointment as Companion of the Most Distinguished Order of St Michael and St George (CMG) in 1967 and finally creation as Knight Bachelor in 1969. He derived great pleasure from all these awards and honours. Those falling to him in the final years of his life were particularly precious to him, namely, the International Symposium on the Principles of Mineral Flotation held in his honour in 1983; the naming of the Ian Wark Laboratories in the CSIRO complex at Clayton; and the renaming of the lecture hall in the Ellerton Becker Building of the Australian Academy of Science as the Ian Wark Theatre. Since his death and in recognition of his contribution to science and industry the Academy has inaugurated the Ian William Wark Medal and Lecture.