260 ADDRESS OF THE RETIRING PRESIDENT [Vol. 76 Address of the Retiring President GEORGE TAYLOR, O.B.E., F.R.I.C. (Delivered after the Annual General Meeting, March 16th, 1961) IN our Society it is the practice that the Presidential Address shall be given at the end of the presidential two years of office. Accordingly, it must be regarded as conventional that the retiring President will refer to the Society’s activities during the preceding two years and will further, with suitable humility, express his personal views on the spirit that has animated the Society-the spirit that must animate any living Society such as ours-and which in its trend has in fact directed either the general or any special activities. With regard to the first matter I am greatly indebted to Dr. Williams, our Honorary Secretary, for his last two Annual Reports, in which he gives a much better r6sum6 of our activities than I can give, and which I therefore regard as perrrtitting me to turn immediately to my second matter.I would, however, take this opportunity of referring to our excellent position with regard to membership and financial status, and paying my personal tribute tc the hard and devoted work of our Honorary Secretary, Dr. K;. A. Williams, and our Honorary Treasurer, Dr. J. H. Hamence, to whom this very satisfactory position is largely due. Coming now to the second matter, I find that over the last two years I have become aware on every side of an increasing consciousneiss of the fundamental purpose of our Society. You will remember that the first object of our Society as declared in our Memorandum of Association, is as follows- “To encourage, assist and extend the knowledge and study of analytical chemistry, whether by the holding of periodical meetings, by the establishment and promotion of lectures, demonstrations, experiments, discussions, conferences or correspondence, by the formation of reading rooms and libraries (whether of reference or lending), or by the publication of newspapers, periodicals, journals, pamphlets, reports or books.” This is the rock on which our Society was founded.The objectives of the Society were at first of course somewhat fluid, and could be regarded as applying only to one branch of analytical chemistry and as being limited in scope. But with the publication of the journal of the Society, The Analyst, the objectives became sharply crystallised.It is interesting to refer to the title page of volume one (1877), where the following is recorded-“The Analyst, including the proceedings of the Society of Public Analysts-a monthly journal of analytical chemistry.” This, however, was altered in the second volume, and then read-‘The Analyst--including the proceedings of the Society of Public Analysts, a monthly journal for the information of those interested in the purity of food and drugs and in general analytical microscopical research.”May, 19511 -4DDRESS OF THE RETIRING PRESIDENT 261 But in 1891 there appears a significant change, for now we find the journal described as “the crgan of the Society of Public Analysts, a monthly journal devoted to the advancement of Analytical Chemistry.” From being a periodical with a purpose, which incidentally included the proceedings of a Society, it now proclaims itself as the voice of a Society devoted to that purpose.And, in effect, the title page has so remained since. During the two years of my office I have had the opportunity of observing very closely the trend of our Society and I have noted the following. The three Groups dealing with the specialised branches of analytical chemistry, Biological Methods, Microchemistry and Physical Methods, have continued to develop, a.nd have pub- lished the results of much original investigational work, so much so that The Analyst now claims many new subscribers on this account alone. Some eighteen members of the Micro- chemistry Group attended the First International Microchemical Congress in Graz, and our Society was there honoured by the conferment on Mr.Ronald Belcher of the distinction of Honorary Membership of the Austrian Microchemical Society. In my view, much of the continued progress of our Society is directly due to the work of these three Groups. The Analytical Methods Committee steadily continues its work of publishing standard methods of analysis, Perhaps most important, because it marks a new departure in this country, is the publication of the first edition of a Bibliography of Standard Methods of Analysis. The work of compiling and editing this Bibliography has been very hard and tedious and has covered some four years; and the thanks of the Society must be given to Dr.Kent- Jones, upon whom fell practically the whole of this work, and who was the originator of the idea and the main-spring of the responsible Sub-committee. Our Society is concerning itself very intimately with the Second International Congress of Analytical Chemistry to be held in England, at Oxford, in 1952. We contributed the money necessary for the initial expenses of the preliminary arrangements, we are well repre- sented on both the Central and the Executive Committees, and The Analyst has been accepted as the organ in which the proceedings of the Congress will be published. Also during the last two years our Society has, through its nominated members, concerned itself with Government legislation in connection with the Fertilisers and Feeding Stuffs Act, the Rivers (Pollution of Effluents) Bill and the Preservative Regulations.One other matter in this connection is the continued increase in circulation of The Analyst-and this despite the increased price to outside subscribers, that is, persons, firms or institutions not members of our Society. It is interesting to mention here that of a total of 2350 of these outside subscribers, no less than about 1600 are scattered throughout the world outside the United Kingdom, in no less than 57 different countries. While dealing with The Analyst I would wish to acknowledge the invaluable work of the Assistant Editors, F. L. Okell and J. B. Attrill, during the many months of illness of our late Editor. Now this is a two years’ record and I have dealt with it at some considerable length as a backgrcund to a matter that has caused me very much concern and one that I regard it as my duty now to deal with to the best of my ability.When I first took office there was a movement among members to alter the name of the Society to one more indicative of its fundamental purpose for the advancement of analytical chemistry, and also to remove from our Memorandum of Association two sections dealing with professional objects. Early in my period of office a resolution to this end was submitted to members at a general meeting but failed to get the necessary majority for its purpose. Since then, however, a new factor has emerged which may well have a great influence on this question, namely, an announcement of the Government’s intention to found a Science Centre.In May, 1950, Mr. Phillips Price, M.P., the Chairman of the Parliamentary and Scientific Committee, a body on which our representative, Dr. H. E. Cox, takes an active part, was fcrtunate in the House of Commons (to quote the Rt. Hon. Viscount Samuel) “in the fact that his devoted work for this Committee was recognised by Providence in giving him the first place in the ballot for Private Members Motions. He seized that opportunity by putting down a resolution on the utilisation of Britain’s scientific resources. Seventeen members of the House of Commons spoke, of whom thirteen were members of this Committee. In November, Mr. Morrison announced, on behalf of H.M. Government, the acceptance of a proposal long advocated for the creation of a new British Science Centre in Londcn.” Sub- sequently, the Rt.Hon. Herbert Morrison, M.P., stated that the actual building of such a Observe the change!262 ADDRESS OF THE RETIRING PRES1DEN.T [Vol. 76 Centre was a long-term policy; the planning of the Centre and the preliminary arrangements were to proceed immediately, and the Royal Society would take a great part in the negotiations. In December, Sir Robert Robinson, in his presidential address at the anniversary meeting of the Royal Society, said that it was possible that the scientific societies wGuld be housed in a worthy and impressive building, and that the quarters of the various societies would be separate, each retaining its individual library. He enumerated the various societies which had agreed to participate, a list of some sixteen.He further stated that it was under- stood that many of the smaller scientific clubs and societies would receive hospitality as they did at the present and had done in the past. But our Society is not included in that list,, although I believe that at least one of the societies included has a membership no larger than ours. There is, of course, no official reason given for our non-inclusion. It is to be observed, however, that all the societies included in the list fall into the general category of “pure” scientific bodies, that is to say, they have no professional interests. It is probable, therefore, that it is because we have professional objects in our Memorandum and our name suggests a professional angle that we are not considered to be eligible.I doubt whether the name carries much weight from this point of view, but certainly the fact as regards our Memorandum is another matter. It may be also that the position of analytical chemistry as a branch of the science of chemistry is not considered of sufficient separate importance to justify a position among the chosen scientific societies; this point, however, I will deal with later. I have referred to the fundamental purpose of our Society, and to the background of our activities during my years of office. I hold the view that as our Society represents analytical chemistry in the United Kingdom, arid that as analytical chemistry, a branch of the science of chemistry, has now attained a status of national importance, the Royal Society could and should be persuaded, even now at this somewhat late stage, to consider favourably any application that we may make for inclusion in the bodies to constitute the Science Centre.I know that: the movement among some members of our Society to remove the particular sections of our Memorandum is again reviving. I think that we are now at a turning point in our Society’s existence. We have to make a decision that will vitally affect our future. We can remain constituted as at present and hope that we shall continue our present excellent progress, or we can reconstitute ourselves with the hope that thereby we shall be admitted into the Science Centre, with the prospect of a permanent home, and of being universally accepted as the Society representing the science of analytical chemistry.I believe that we cannot possibly evade this issue. Personally, I am convinced that we should be a body devoted only to the advancement of the science of analytical chemistry without any professional interests; and as a professional analyst I am now also convinced that my professional interests would best be served by a separate but closely connected association devoted to that special purpose. This is not the time or place to go into the question of how such reconstitution could be brought about, but I am aware of suggestions, which have been put forward after grave consideration, that offer a course of action that might well be acceptable to all members of our Society. Coming now to the question of the status of analytical chemistry in the chemical world, it has repeatedly been urged that this is not properly recognised.It is said that analysis is regarded as the handmaiden but not as an essential branch of chemistry. L. Eynon, my predecessor in the presidential chair, laid emphasis in his presidential address1 on the desira- bility of recognition by the Universities by the institution of Chairs of Analytical Chemistry. The President of the Royal Institute of Chemistry, Professor J. W. Cook, in his presidential address in Glasgow,g in 1950, referred to the need to publicise the work of chemists and their real achievements as opposed to the popular conception of men engaged in the develop- ment of the destructive forces of atomic energy; and although not specifically referred to, his address quoted instances of analytical achievements.C. L. Wilson3 has also recently dealt with this subject in considerable detail ILn an article on “The Future of Analytical Chemistry.’’ These are all typical of many earnest endeavours in many places towards the same end. Where, however, they fail to some extent is in their direction and their aim; and in the method of attaining publicity. To a large extent they consist of claims and statements made in wide and general terms. These I fear do not have sufficient weight; they constitute the advertisement, but there is I think much to be said for the old adage, as forceful to-day as it was in the yesterdays, that the proof of the pudding is in the eating. We should, I believe,May, 19511 ADDRESS OF THE RETIRING PRESIDENT 263 progress much more rapidly in general acceptance if we would talk more about what has been accomplished by analytical chemistry and what it would be fair to say could not have been accomplished without the aid of analytical chemistry. Taking this point of view, I propose to give a brief survey this afternoon of some examples of the Service of Analytical Chemistry in Food and Agriculture, within the particular field in which I work.ANALYTICAL CHEMISTRY IN THE SERVICE OF FOOD AND AGRICULTURE In submitting my thoughts on the services of analytical chemistry to food and agriculture, I am immediately concerned with the fact that generally when food and agriculture are referred to collectively the emphasis is on food and matters connected directly with food, and the subject of agriculture is relegated to the background.It is of course natural that life should be considered in terms of food. Of all the forces that influence, govern, or determine the life of a people-religion, education, physical comfort, social amenities, the law-none is greater than food. But what is not so generally recognised is that food is co-existent with agriculture, its quality and quantity are dependent on the quality and quantity of agriculture; the question of food supplies cannot be properly considered inde- pendently of the question of agriculture. I t is a biological law that man cannot live without plants. It is for this reason that in discussing, and putting forward instances of, the service of analysis, I have thought it desirable to deal, in the main, with agricultural matters.At the present time, service to food and agriculture can scarcely have any real significance other than that of increasing productivity. The problem of an increasing population without a corresponding increase in the food supply is a topic of everyday conversation. Although this question is outside the particular purpose of my talk and has beendealt with recently at length by Professor S. Z~ckerman,~ under the heading of “Food Production in Relation to National Economy,’’ I should, however, like to show you a table from the 1947 F.A.O. report which shows vividly the position of the U.K. in this matter (see Table I). TABLE I F.A.0. REPORT, 1947 Greece . . .. Rumania.. .. Poland . . . . Hungary ..Italy . . .. Belgium . . .. Netherlands . . Germany.. .. France . . .. Sweden .. .. Denmark .. United Kingdom England and Wales .. . . . . . . . . .. . . .. .. .. . . .. .. .. .. .. . . . . .. .. . . .. .. a . .. .. .. ,. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. * . .. . . .. .. .. Acres of arable land per person 0.74 1-53 1-70 1.33 0.74 0.30 0.27 0.69 1-24 1.46 1.73 0.27 - Rate of population increase per 1000 11-8 6.9 10.1 11.2 9.4 1-2 11.6 7.6 0.4 3.1 7-6 2.2 - Years needed to double population 69 118 69 62 74 679 61 92 224 93 314 - - It will be noted that the U.K. and the Netherlands have the smallest amount of arable land per person, Agriculturists generally are being encouraged on the highest levels to increase pro- ductivity. It must be recognised, however, that there is little parallel between an increased productivity in industry of the necessities, other than foodstuffs, of our modem civilised life and an increased productivity of foodstuffs.With the former, articles are produced more or less unalterable and ready for use. On the other hand, the production on a farm of a certain amount of food, either animal or vegetable, does not mean that that same amount will be available for consumption. It may suffer, either while being grown or in the interval between full growth or harvesting and consumption, from one or more possible causes of deterioration, such as disease, breakdown and decomposition due to inherent natural vital activities, the action of bacteria or fungi, or the attack of insect or rodent pests.Viscount Bledisloe,6 in his presidential address to the Second International Congress of Crop Protection, 1949, stated that a conservative estimate of the loss due to this cause, excluding weeds, is This fact has the greater implication in an island like the U.K.264 ADDRESS OF THE RETIRING PRESIDENT [Vol. 76 given at 30 per cent. of crops growing, harvested and stored, and the F.A.O. has estimated the annual loss of grain at approximately 65 million tons. Again, separate farms may yield the same weight of produce, yet the produce of one may have significantly greater nutritional value, quite apart from any question of decom- position or the effects of outside deteriorating agencies. That is to say, the productivity of agriculture cannot be assessed, from the national point of view, only in terms of weight or volume, it must also be assessed in respect of nutritional value.This fact is so important that it hardly needs stressing, but it brings me to my first example of the service of analytical chemistry. COBALT AND ANIMAL HEALTH Recently, an agricultural correspondent in, an article on New Zealand in The Times6 referring to the frequently repeated warning t!iat the world must soon go hungry because human beings are increasing rapidly and there is no new land that can readily be brought into food production, points out that there are many square miles in the North Island of New Zealand waiting for development. To quote: “New Zealand’s youngest soil was created with the Napier earthquake in 1931, but much more was made in 1886, when Mount Tarawera erupted and showered ashes and mud over 6’700 square miles.This pumice soil, which grows useless tussocks and the scrub ‘ti-trees’ (Manuka) when left to nature, can quickly be transformed by burning, cultivating and fertilising into excellent grazing country for cows, beef cattle and sheep. The new soil which is friable and easily worked will grow abundant rye grass and clover. The key to this new wealth was found by incorporating a trace of cobalt (6 lb to 1 ton of superphosphate in the fertiliser dressing).” You will observe this quite casual reference to cobalt, an element which cannot be described as well known to the average person. But, in fact, it was a considerable amount of analytical work that discovered this key.For many years settlers in certain areas in New Zealand and Australia had experienced severe losses of sheep and cattle from “wasting diseases” of unknown cause. Animals, after grazing for several months, lost their appetites, wasted and finally died, although feeding in a luxuriant growth of pasture. Horses fed in the same areas remained in excellent health. Spectacular recovery followed change to other pastures, although apparently these were inferior in quality and quantity. The clinical picture was that of chronic starvation. I t was natural enough, therefore, that the earliest treatment was for anaemia, and consisted in dosing with iron compounds. At first this seemed successful in New Zealand, as cures were obtained with the aid of massive doses. You will note the massive doses! But later work in Australia suggested that the curative agent was some impurity in the iron compounds.(Hence the need of massive doses.) It was also observed that while the amounts of iron found in good and bad pastures were not significantly different, there was often a very marked difference in the type of soils. Limonite soils were generally-though not invariably-good soils. So much so that treatment of the affected animals with drenches prepared from limonite had generally proved so effective that they were in common use. But these drenches were not invariably successful, so the next siep was to add copper salts to the drenches, on the assumption that the value of the massive dosage of iron was due to traces of copper. It was at this point that the analytical approach to the problem began to appear of significant value.Dilute hydrochloric extracts of curative limonites proved effective, even after removal of iron from the extracts. Further fractionation showed that the potent element was in the , fraction containing nickel, manganese, cobalt and zinc. Tests that followed with supposedly pure nickel oxide indicated nickel as the cur<ative agent, until it was subsequently found that pure nickel chloride failed. Now, from another part of Australia, came the suggestion that the wasting disease, known locally as “coast disease,” was due to lack of one of the trace elements, together with the further suggestion that cobalt might be required in ruminant nutrition, the latter suggestion being based on the demonstration a few years previously of the effect of traces of cobalt on rats.Analysis of the nickel compound showed the presence of substantial amounts of cobalt. The solution of the problem was found. In affected areas of Western Australia, sheep were kept inL excellent condition by a daily dose of 0.1 mg of cobalt, and cattle by from 0.3 to 1.Omg. In South Australia, however, it was found that copper as well as cobalt was necessary for complete cure. About the same time, in New Zealand, it was independently established by Askew and Dixon’ that the effectiveness of ores and soil drenches was related to their cobalt content. The story of cobalt deficiency in animals is; a fascinating one. This proved fallacious.May, 19511 ADDRESS OF THE RETIRING PRESIDENT Consideration of some of the results of analysis are interesting (see Table 11).265 TABLE I1 COBALT CONTENT OF PASTURES, ETC. Cobalt, p.p.m. (in dry matter) “Pure nickel oxide” . . .. .. .. .. .. 7000 Ferric ammonium citrate . . . . .. .. .. 24 Limonite .. .. .. .. .. .. .. 2 to 55 “Nelson” soil . . . . .. .. .. .. .. 45 Acid extract of top-soils, bad . . .. .. .. .. 0.09 to 0.23 Y3 $9 good . . .. .. .. 0.26 to 0.94 .. .. average 0.038 Healthy pasture . . .. .. .. .. .. average 0.106 Unhealthy pasture . . .. .. . . Livers of unhealthy sheep . . .. .. .. .. 0-02 to 0.03 Livers of healthy cobalt-treated sheep . . .. .. 0.07 to 0.25 Since then many other investigations have been carried out in various parts of the world and cobalt deficiency has been found t o be the cause of apparent malnutrition in many places, even in some parts of Scotland.One fact brought to light by this work was illuminating. While it was now established that cobalt is an essential factor in ruminant nutrition, it seemed clear that very much smaller amounts, if any, are required by non-ruminants. Though it might well be said that the original problem had been solved, the interesting problem of how the traces of cobalt function and why in one class of animal they should be necessary, and not in the other class, remained unanswered until quite recently, when light was thrown on this question by J. Tosie and R. L. MitchellS with the aid of recently-developed methods of analysis using radio-active techniques. When radio-active cobalt was injected intravenously into adequately fed cattle and its course traced, somewhat surprisingly poor absorption of the element was shown, but some unexpected results were also shown which led to the examination of the micro- organisms in the rumen by the application of a spectrographic method for the determination of their cobalt content.This appears to have been an extraordinarily fertile line of investiga- tion, for it established a reasonable possibility that the rumen micro-organisms accumulated cobalt from their external environment. The findings suggested that (1) in cobalt-deficient sheep the host and the microbes compete for the already low concentration of cobalt available in the feed; or (2) that cobalt may be essential for the micro-organisms and not for the host; or (3) that absorption of the element by the host would deprive the micro-organisms of a factor essential for their growth and metabolism.Conversely, if cobalt is an essential metabolite for the host, then its concentration in micro-organisms may reduce its availability for the host. But I would contend that it is an outstanding picture of how analytical chemistry first indicated the cure for a serious cattle disease and then, with the advance in the science, began to sketch in the cause of the trouble as a background to the picture. In their account in Nature, Tosie and Mitchell finally add the comment that it is of interest to note that cobalt has been found to occur to the extent of 4.0 per cent. of the crystals of the naturally occurring anti-pernicious anaemia fact or.GRASS IN ENSILAGE I t is accepted by many thoughtful agriculturists that from a national standpoint the greatest scope for increased home food production lies in raising the productivity of our grasslands. Sir George Stapledons suggests that nearly one-third of the land surfaces of Great Britain is in rough and hill grazing and by far the larger proportion lies comparatively snug below the 1500 ft. contour. In general terms and on technical grounds there is no reason why this land should not be made the master instrument in producing an honest meat ration for all of us, here at home. The Minister of Agriculture1* put the possibilities somewhat tersely when, at the Smithfield Show in London in December, 1949, he gave the farmers the slogan “Ten per cent.more grass from ten per cent. less land.” Professor S. Zuckerman4 puts the point that an increase from the present 11 cwt of starch equivalent per acre to 14 to 15 cwt of starch equivalent per acre would mean an additional approximate amount of 3+ million tons of starch equivalent, equal at the ruling price to El00 million. This is the picture to date. I t is clearly not yet finished.266 ADDRESS OF THE RETIRING PRESIDENT [Vol. 76 Professor Zuckerman favours artificial drying of grass rather than ensiling, but this question is controversial. The assessment of quality is largely dependent on chemical analysis, and of late years new factors, such as “trace elements,” protein constitution and mineral composition have added to the difficulties of the assessment.Moreover, the calculations for that useful unit of measurement, “cwt of starch equivalent per acre,” can only be made from analytical data. The following table, by R. A. Hamilton,lf illustrates the present-day value of grass- TABLE I l l ESTIMATED QUANTITIES OF STARCH EQUIVALENT AND PROTEIN EQUIVALENT PROVIDED BY CROPS AND GRASS IN THE U.K. I N 1948 Million acres Starch Per cent. Protein equivalent of total equivalent Million tons 13.1 Arable crops . . .. .. . . 11.0 49 1.1 17.9 Grass-temporary and permanent. . 9.9 45 1-8 17.2 Rough grazings . . .. , . 1.3 6 0.1 Total 48.2 22-2 3-0 The available calculated figure for utilised starch equivalent for grasslands in is from 10 to 12 cwt Der acre. Per cent. of total 37 60 3 the U.K. Although man d6es not eat grass and the objection to these figures that they over- emphasise the importance of grass can therefore be raised, the extent to which arable crops are used for livestock feeding is often forgotten.TABLE I’V ESTIMATED QUANTITIES OF STARCH EQUIVALENT AND PROTEIN EQUIVALENT PROVIDED It is illustrated in Table IV. I N THE U.K. I N 1948 BY CROPS AND GRASS WHICH WERE EATEN BY LIVESTOCK Starch Per cent. Protein Per cent. equivalent of total equivalent of total Million tons Arable crops . . .. .. .. . . 6.8 38 0-7 27 Rough grazings . . .. a . . . 1.3 7 0.1 4 Grass-temporary and permanent. . . . 9.9 55 1.8 69 Total .. .. .. . . 18.0 2.6 Grass is ordinarily utilised in several ways. It may be directly grazed, or cut frequently during the growing season and immediately artificially dried, or cut at or towards the end of its growing season and dried naturally to produce that age-old product, hay, or it may be cut and ensiled.Regarded as a source of protein-or meat in embryo-there must always be discussion as to the best way to treat grass that cannot be directly grazed. On this point it is to be observed that silage is a succulent and palatable article very largely used as a staple cattle food in the dairy countries of Denmark and Holland, and it is stated that most of the dairy farms of any size in the U.S.A. possess a silo, because in the early days young maize-a crop extensively grown there-is particularly suitable for ensiling. In the U.K., however, silage has had a chequered career. Prepared from a mixture of cereals and legumes, e.g., oats and vetches, it attained considerable popularity at the end of the nineteenth century.But the practice declined, probably because although the silage then produced was a sweet and palatable food, it was produced at a high temperature from crops at an advanced stage of growth and its feeding value was low. Also it was in direct com- petition with hay-making. Now, within the last ten or twenty years, there has been a very strong revival, due without doubt to a better understanding of the chemistry involved in the underlying principles as interpreted by analysis of the constituents produced during the varying phases of its preparation. This is shown in detail and at considerable length by Sir S. J. Watsonf2 in a recent article on the chemistry of ensilage.After describing grass silage as to-day’s most important and most promising of the foodstuffs that can be produced on the farm, and further asserting that if we are to survive present-day economic conditionsMay, 19511 ADDRESS OF THE RETIRING PRESIDENT 267 its use on farms will have to increase in a marked degree, he deals convincingly with the nutritional evaluation of silage by consideration of analytical data. When cut, the crop is alive and respiring; in due course the cells die and the micro-flora come into action. The time interval and forms of organic breakdown can be controlled and influenced by physical means and aerobic and anaerobic conditions so that the silage produced shall be of the highest nutritional value and of a satisfactory palatability.Analytical investigation of the various types of silage produced under varying conditions of aeration due to packing, and of the temperature of the mass, led to an evaluation of such end-products as butyric, lactic and acetic acids, alcohol, carbon dioxide, amino-acids, fatty acids, valatile bases and ammonia. Thus, butyric acid over 1 per cent. means a silage that must be fed with caution, but is controllable because the butyric organisms cease growth at pH 4-2. Acidity produced by lactic acid organisms is considered a most important factor, and the lactic acid may reach 2 per cent. by weight of the fresh silage. Good quality means more than 1 per cent. of lactic acid, and in greater amount than the volatile acids. Mould growth with volatile bases and ammonia is restrained by high acidity, i.e., a low pH.These essentials for a good silage would indicate that the crop should be harvested when it is richest in carbohydrate, that is at a late period in its growth; but this, unfortunately, is when it is poorest in protein. The difficulty has been resolved by adding extra carbohydrate to the grass in the silo; this makes it possible to reap the crop at an early stage of growth when its protein content is at a maximum. The English practice is to add molasses, in the U.S.A. the additional carbo- hydrate is supplied by the addition of sugar-beet pulp, potato meal or even whole potatoes. Another modern procedure to encourage the lactic acid organisms is by artificially lowering the pH below 4 by the addition of dilute mineral acids, usually hydrochloric and sulphuric acids, this procedure being in principle the well-known Continental A.I.V.process. Finally, the feeding value of a silage can be quite properly judged by determination of the amounts of dry matter and nitrogen (crude protein) and the pH value. Colour is a good guide to the carotenoid value. It would appear that present-day practice in the manufacture of good silage owes a very great deal to chemical analysis. METALLIC CONTAMINATION OF FOODSTUFFS-CROP PROTECTION : PEST CONTROL I have put these two apparently somewhat dissimilar subjects together because they are intimately associated. Commonly, the metallic contamination of foodstuffs occurs during the course of manufacture, that is, during the course of the journey from the raw material to the finished product. On the other hand, contamination due to crop protection or pest control occurs before the plant becomes the raw material of commercial practice.Nevertheless, the final result may be the same: a potential cause of toxicity or malnutrition or illness to the human or animal consumer. It is well in the first place to consider the question of toxicity or poisonous quality. It is not easy to assess poisonous quality. There are some substances that appear to be potentially harmful, that is to say, poisonous, in the smallest quantities-and this quite apart from idiosyncrasy-while others, although definitely harmful if taken in any sub- st antial amount, are apparently harmless in traces. Furthermore, the position is becoming increasingly complicated with the advance of analytical practice and the development of inore sensitive and more comprehensive tests with the aid of which the physiologist or bio- chemist discovers more and more elements essential to human life in yet more minute traces.The question therefore arises: Is there in fact a proportion or amount of each of the so-called poisonous metals that is essential to life and can be assumed to be non-poisonous or harmless in the proportions naturally present ? This question possibly really concerns only metallic contamination of foods, because the increasing tendency in crop protection and pest control is to use synthetic organic chemicals, such as DDT, or the phenoxyacetic acids, which can hardly be considered as natural to life in the same sense as may the minute traces of the now very large number of elements found to be normally present in vegetation. It seems likely that others will also be found to be essential.For instance, it is now suggested that that popular aid to murder and suicide-arsenic-belongs to this class. Bearing all this in mind it may well be regarded as fundamental to know whether any proportion of any one poisonous element can be considered as harmless. The answer to this question becomes of importance to the analyst when having found so many parts per million, or so many micro- grams per ounce, of, say, arsenic or lead in a food, he is faced with the necessity of giving an268 ADDRESS OF THE RETIRING PRESIDENT [Vol. 76 opinion as to whether or not the food is safe for human consumption.Clearly no analyst can answer this question from knowledge gained from personal experience. He must seek the aid of medical or physiological authorities. Let US then examine the evidence of these authorities. Perhaps the first to consider are -the findings and recommendations of the Royal Commission on Arsenical Poisoning published in 1903. During the course of the year 1900 medical men in Lancashire and Staffordshire became aware of a serious increase in the illness generally diagnosed as alcoholic peripheral neuritis. This increase became so marked as to become epidemic in certain areas and to necessitate a closer and more critical examina- tion. I t was then observed that while alcoholic peripheral neuritis was normally an illness of spirit drinkers, the victims in this instance were generally beer drinkers.This led to examination of the beer particularly implicated, first for lead, then for higher alcohols, then for mineral poisons generally, these being the suggestions which arose successively. But these examinations yielded negative results. In November, 1900, however, Dr. Reynolds, of Manchester, recognised that one of the common skin symptoms-shingleewas also a common result of medicinal arsenical treatment. He applied the Reinsch test to the beer, obtained a good positive result; Dixon-Mann confirmed his findings, and so the cause of the trouble was found. It is estimated that from 2000 to 3000 illnesses, and about 100 deaths were caused by arsenical beer. In the period 1901 to 1903 (when the final report of the Royal Commission was published), an immense amount of investigational work was under- taken, both in respect of the analytical methods for the determination of arsenic, and in respect of arsenical contamination of foodstuffs ; work in which our Society participated as well as the Government Laboratory and a brewers’ research association.In 1903 the final report of the Commission, recommending maximum limits of 1/100th of a grain of arsenic per pound and per gallon respectively for solid and liquid foodstuffs, was published. Thus we have one authoritative recommendation, not an Order or Regulation, in respect of arsenic -and I shall return to it presently for another reason. But other than this the analyst will find himself in difficulty. Medical and physiological literature abounds in data con- cerning the toxicity of poisonous elements.Mainly they are concerned with fatal, or near-fatal, doses, and the duration and character of the accompanying symptoms. On the question of what may be described as tolerances for human beings, there is little information. This is understandable, as experimental work on humans in order to ascertain degree of tolerance to poisons is not usually regarded as permissible. On the other hand, a very considerable mount of work has been done in connection with the reactions and well-being of animals, both large and small, and the available data is extensive and comprehensive. But however sound the general application of such data to humans may be, it cannot be accepted when the question arises as to whether or not a specified minute trace is harmful or beneficial, or whether a specified minute trace exceeds the safe limit. The angle from which the problem in respect of human beings has been attacked so far- and it is difficult to see any other line of approach-is, in short, to add together the amounts of the particular element under consideration that are normally present in the daily diet, the amount normally present in the liquids that may be drunk daily and the amount inhaled in the dust of the atmosphere. The figure so obtained then constitutes the basis for an assessment of what may then be described as the safe daily limit.It will be seen that this approach is dependent on very comprehensive analytical data, and for many elements it is not available.That it is a sound a proach, however, would appear to be very substantially confirmed when the applications of t K e recommendations of the report on arsenical poisoning referred to earlier are reviewed and considered. These recommendations have now been in force over forty-seven years, and have been generally accepted. During that long period I think it is safe to say that there is no significant clinical or physiological evidence that the daily ingestion of foods and liquids which may contain arsenic, but not in excess of 1.4 and 0.14 p.p.m. respectively, has led to any illness or other harmful effect. That is to say, such maximum limits for arsenic may now be accepted as safe limits for human beings. That is also to say, a safe limit for one poisonoris element has been established practically entirely on the basis of data supplied by the analysis of foods.And I would venture to say that it could not have been established in any other way. So much for arsenic. Now official action seems likely in connection with limits for other potentially poisonous elements, particularly lead: so that if the same method of attacking the problem is pursued, then analysis still remains as the dominating factor for determining the answers. But they are limited data.May, 19511 ADDRESS OF THE RETIRING PRESIDENT 269 I t will be seen from the foregoing how intimately crop protection and pest control is connected with contamination of foodstuffs. When a crop is dusted or sprayed with a fungicide or an insecticide it is a reasonable requirement that these shall remain effective for a significant period of time.It follows that, despite the action of wind and rain, there is always the possibility that they remain still effective to some extent when the crop is marketed for human consumption. It will further be immediately observed that this widens the whole question enormously. Whereas the older kind of chemical used for the purpose of pest control can be generally described as metallic poisons, e.g., lead, arsenic, and copper compounds, the newer methods of control depend on the use of synthetic organic chemicals, many, if not most, of which are of unknown toxicity to human beings. The problems that apply to the metallic contamination of foods, therefore, apply even more strongly to these newer poisons, particularly when it is realised that analytical control must now be dependent on the development of sufficiently sensitive and precise methods of analysis.COMMERCIALISED PHOTOSYNTHESIS AS A SOURCE OF INCREASED FOOD SUPPLY In recent times consideration of the increased food needs of the present day and of any possible new sources of supply has focussed attention on the observation that while only a small proportion of the solar radiation suitable for the photosynthetic reduction of carbon dioxide by plants is actually converted to chemical energy in this way-the efficiency of the primary producers of agricultural economy, the so-called higher plants, amounting to only about 1 per cent. and not being susceptible to much improvement-certain uni-cellular forms of life can under suitable or appropriate conditions attain a much greater efficiency. Some algae, such as the Chlorella species, can utilise as much as 30 per cent.and may possibly TABLE V YIELDS FROM CHLORELLA COMPARED WITH CROP PLANTS U.S. tons per acre per crop year, Source dry weight Chlorella . . .. .. .. 2.85 1-74 1-66 1.15 0.75 0.46 Flax (seed) . . .. .. .. 0.70 Soya (seed) .. .. .. 0.63 Groundnut . . .. .. .. 0.60 Percentage of fat 7.0 17.0 42.0 66-5 55.0 78.0 37.0 18-0 30.0 lb. fat per acre per growing season of 120 days 400 693 1390 1303 747 687 51 8 227 360 attain a maximum efficiency of more than 80 per cent. In the higher plants th,e products of photosynthesis are translocated to non-photosynthetic structures or organs in the plant, but a Chlorella cell multiplies by simple division into daughter cells, each of which is capable both of growth and photosynthesis, and there occurs no diversion of the products of energy derived from solar radiation to support the growth elsewhere in the cell.It has now been found that the direction of what may be described as the metabolic activity and the detennina- tion of the end-products of such activity in algae is dependent, among others, on the following conditions: the supply of essential nutrient elements, the incidence of light of suitable wave- length and intensity, a controlled range of temperature and constant aeration, including a minimum of carbon dioxide. It has been found that the main product can be either protein, carbohydrate or fat, according to the stage of growth, the strain or variety of algae and the cultural conditions; and that in connection with the latter the most important factor is the concentration and nature of the combined nitrogen in the medium.The position t o date, as shown in a very recent contribution by W. H. Pearsall and G. E. Fogg13 from which this summary is taken, may be described as only in the experimental stage, although trials are reported of large-scale continuous culture in California for a period of over two months, where it is claimed that 6 per cent. of the incident sunlight was utilised in the produc- tion of organic matter. So far the investigational and experimental work show the following results. Different algal groups under differing cultural conditions and with differing nutrient media have specific tendencies towards predominance of protein or fat or carbohydrate.270 ADDRESS OF THE RETIRING PRESIDENT [Vol.76 The value of these algal proteins, fats or carbohydrates, from the point of view of human nutrition, is still however largely undetermined because the knowledge of this chemistry is incomplete, that is to say, they have not yet been subjected to comprehensive and detailed chemical analysis. What is known to date ist that the proteins, theoretically the most economical food products of the controlled growth of algae, may well be of very low grade, lacking some of the essential amino-acids and containing substantial proportions of nitrogenous bases; the lipid fraction includes from 20 to 80 per cent.of fatty acids with a large proportion of unsaturated acids; and that although the carbohydrate portion includes some sugar and starch, there appears to be no published detailed analysis and it is thought to be largely of doubtful value in animal nutrition. The authors conclude with an interesting table of yields from Chlorella compared with crop plants, and with the suggestion that as a means of supplementing our resources simple algae have considerable potentialities and are well worth further investigation from this point of view (see Table V). I would add that clearly such investigation waits on the analyst. IRRIGATION AND SOIL CONDITIONS In the U.S.A., soils low in organic matter, poor in permeability to water, often con- taining an accumulation of salt and of extremely low fertility, occur in many river valleys and are known under the generic name of black-alkali soils.Usually the pH of these soils is in excess of 8, sodium is the predominant exchangeable base, and the organic matter may tend to dissolve in alkaline solution. The association of black-alkali formation with sodium carbonate and biczrbonate in irrigation waters was pointed out as far back as 1911, and was then used in rating formulae for irrigation waters; subsequently, the question of the influence of salts in irrigation waters was discussed when considering land reclamation and agricultural production in a north-western area cbf the U.S.A.; and in 1950, Frank M. Eaton, of the U.S. Department of Agriculture and Texas Agricultural Experimental Station,l4 published a paper entitled “Significance of Carbonates in Irrigation Waters,’’ in which he first points out that “in terms of the difficulty and cost of reclamation and the severity of its effects, black-alkali continues to occupy a prominent position among the unfavourable consequences of irrigation,” and then proceeds to postulate as fundamental that the problem can only properly be attacked by consideration, in the first place, of the character of the water, as indicated by fully detailed analytical examination; it is only when these data are known that the potential physical effects of the passage of the water through the soil can be forecast or assessed and a suitable method of reclamation outlined.Only occasionally does it occur that a water supply contains a sufficiently high concentration of salts to be directly harmful to plants; but as the irrigation water becomes thle soil solution and loses volume and suffers changes due to concentration, to plant uptake, arid to base exchange, then the picture alters.The author discusses at some length the quantitative significance of the relative amounts of Ca, Mg, Na and HCO, and CO, ions upon which depend the possibility of an ultimate condition of alkalinity due to sodium carbonate, and also the types of soil that may be developed in time and in absence of good drainage or when used too sparingly, namely: (1) calcium saline soils, produced by waters much higher in Ca .f Mg than HCO, + CO, and which have relatively low Na value, usually readily reclaimable by draining and leaching; (2) sodium saline soils, produced by waters which initially or after partial evaporation and the precipita- tion of CaCO, have high Na values but no residual Na,CO,, which then deteriorate in pennea- bility unless the water remains fairly saline; and (3) alkali soils, saline or non-saline, produced when irrigation waters containing more HCO, $- CO, than Ca + Mg are used so sparingly that little leaching occurs.In the case of the last-mentioned type, however, if the Na is not too greatly in excess of Ca and Mg, and enough of such water is used that drainage continues to contain a substantial proportion of Ca and Mg, there may be no ill effects. Perhaps the most generally interesting pan: of this paper is the author’s observation that the discussion presented in it is the outcome of observations of the effects of prolonged use of water in two of the world’s oldest irrigated areas: in Egypt, along the Nile, where black-alkali occurs, and where reclamation is now being accomplished in certain districts by providing drainage and then leaching with water from the same source as that which produced the condition; and in Iraq, along the Tigris and Euphrates, where the accumulation of salt in the land has been sufficient to account for a major decline in population >and damage to a great civilisation. With regard to the Euphrates, it is pointed out that the character of the river water is such that it would have supported a flourishing irrigation agriculture hadMay, 19511 ADDRESS OF THE RETIRING PRESIDENT 271 the people, through the centuries, recognised the need of drainage to carry away the excess of salt; but there is no record of any ditch ever having been dug for this purpose.Confirmation of at least one of the points emphasised in the above conclusions is inde- pendently afforded in a letter on problems of irrigation by E. Hayward,15 in Chemistry and Industry, in December, 1950, when the writer deals with his personal study of the extensive irrigation system of the Punjab in North India. Here, owing to financial difficulties, the irrigation canals had been built without linings, with the result that in the course of fifty years large areas of the Punjab have been and are being thrown out of cultivation owing to constant seepage from the canals into the soil.The seepage gradually raises the sub-soil water level, which may ultimately produce swamps, but in any case brings the dissolved salts in the sub-soil water sufficiently near the surface of the soil for capillary action to come into operation, with the result that evaporation by heat of the sun causes a concentration of these salts in the surface soil and a consequential base exchange of sodium for aluminium, etc., in the surface soil. There is thus produced an untillable clay which will only support a sparse and reedy vegetation, and is quite incapable of bearing crops of foodstuffs. FERTILISER TECHNOLOGY RESEARCH IN THE U.S.A. If it is accepted that in any estimate of the potential crop possibilities of the agricultural land still in existence as such in this world, the assistance afforded by “artificial” fertilisers must have a significant bearing on the estimate, then the programme of future research in fertiliser technology, as recently outlined by K.D. Jacob,16 will have a very great interest for us. In the first place it may be briefly pointed out that while originally (1911) the emphasis in this research lay in exploration and investigation within the U.S. to determine possible sources of supply, it is now more particularly directed to transformation of nitrogen, phosphoric acid and potash into high analysis compounds of satisfactory physical condition and better efficiency for crop production, evaluation of new products as sources of plant nutrients and study of the consumption of plant nutrients-factors affecting consumption and trends in fert iliser usage.The U.S.A. current programme includes the following general lines of investigation- (1) Production of high analysis, synthetic nitrogen fertilisers of low solubility and (2) Quality of water-insoluble nitrogen in commercial mixed fertilisers. (3) Composition, properties and fertilising value of phosphates made by thermal and other processes. (4) Factors influencing moisture absorption , caking, drillability and other physical properties of fertiliser materials and mixtures, including chemical reactions that cause loss of available plant nutrients during preparation and storage of mixed fertilisers. controlled rate of availability to crops. (5) Development of improved methods of fertiliser analysis.(6) Evaluation of agricultural liming materials. (7) Studies of domestic and world resources, technology, production, consumption and trade of fertilisers and fertiliser materials. Let us briefly consider this programme. Perhaps, in the first instance, it is of interest to glance at the approximate composition of Florida Land Pebble Phosphate, as compiled by K. D. Jacob and shown in Table VI. Discussing the programme we have- Item 1-This, at the moment, is particularly directed to the use of products known as “urea-form,” i.e., the plastic product of the interaction of urea and formaldehyde containing about 38 per cent. of nitrogen. Different ratios of the constituents result in products of different solubility. Greenhouse and field experiments indicate that owing to its low solubility and slow rate of availability it shows promise of being a superior fertiliser for long-growing crops that require substantial quantities of nitrogen throughout the season.Grass appears to be specially benefited by its application. A considerable amount of work is being done to assess rates of hydrolysis, nitrification and nitrogen availability of this material for the purpose of evaluating its fertilising value by an analytical method rather than by pot or field experiments. I n this connection I should like to refer to the outstanding work of one of our members, J. H. Hamence, in this field. For a number of years he has studied the nitrogen availability of fertilisers by an analytical method of a semi-biological nature, whereby the extent of the272 ADDRESS OF THE RETIRING PRESIDENT [Vol.76 nitrification that occurs when the fertiliser is mixed with soil in proportions common to agricultural practice, and with adequate cont:rols, is measured by the amount of nitrate produced. The results of his earlier work has already been published,17 but there is much more yet to come. Included in the fertilisers on which he has worked are the urea - form- aldehyde plastics. Item 2 T h i s is really an extension of the work referred to under Item 1, as it is a comparative study of the present official (in the U.S.A.) method for determining the avail- ability of water-insoluble nitrogen by treatment with permanganate, and of the rate of TABLE VI COMPOSITION OF FLORIDA LAND . . ... . .. .. .. .. . . . . .. . . . . . . . . . . .. .. . . .. .. .. * . . . .. .. .. .. .. . . . . .. .. . . . . .. .. . . .. .. . . a . .. .. .. . . .. . . .. .. .. .. .. Organic carbon . . N .. .. .. Total water . . . . .. .. .. . . .. .. .. . . . . .. .. .. .. . . . . .. .. .. .. .. .. .. .. .. . . .. .. * . nitrification. In this brief account by .. .. .. .. .. .. . . .. .. .. . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. * . .. .. .. .. .. .. .. . . . . .. .. .. PEBBLE .. . . . . .. .. . . .. . . .. . . .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. .. PHOSPHATE Per cent. 30.0 to 36.0 0-7 to 2.6 0.7 to 1.1 46.0 to 50.0 0.05 to 0.6 3.5 to 3.9 0.003 to 0.03 0.0008 to 0.002 7.0 to 10.0 0.002 to 0.05 0.05 to 0.6 0.05 to 0.5 0.2 to 1.5 0.03 to 0.08 trace 0*0005 to 0.003 0.003 0.005 0.002 0.002 trace to 0.02 trace to 0.015 0-002 to 0.01 0.001 to 0-005 trace 1-5 to 4-5 0.25 to 0-4 0.005 t o 0.02 1.3 to 2.6 Jacoblf; no indication of the methods adoDted for determining rate of nitrification are give< but p:robably they are on the lines of the Hamence method.Item 3-Comparison of solubility tests of phosphates produced at high temperatures, e.g., glasses such as calcium metaphosphate and the phosphate rock - magnesium silicate fusion product cooled in such a way as to preclude partial crystallisation and then finely ground, as determined by such procedures as shaking with ammonium citrate solutions, with the yields obtained in field-growing experiments, seems to be giving interesting results.Item &This clearly calls for over-all analytical control. Items 5 and &These also are obviously analytical. It would surely not be an exaggeration to say that the fertiliser technology research programme of the U.S. Department of Agriculture is based on the use of all resources of modern analytical chemistry. GENETICS AND ANIMAL COMPOSITION Doubtless most of us have been more than a little interested in the controversy which has recently seriously disturbed the quiet and even tenor of the Soviet scientific way of thought. I refer, of course, to the Vavilov - Lysenko controversy, which, fundamentally is a question whether genetic factors or environment influences directly determine the progressive evolution of life, particularly in respect of plant life.John Hammond,18 in an illuminating discussion of the genetic differences in the composition of animal products, has clearly shown that if such genetic differences have any bearing in the controversy then it is only with the aid ofMay, 19511 ADDRESS OF THE RETIRING PRESIDENT 273 intensive methods of analysis for resolving the primary composition of animal products that any really powerful contribution to the discussion can be put forward. Thus, in the instance of milk-the only possible food for the just-born, and therefore presumably in- evitably the vehicle for any continuing genetic factor that may be potentially operative- the statement that “the higher evolutionary forms of milk, such as that of the cow, repeat in general, in their development in the individual, the composition of milks of the lower evolutionary forms” can only be supported by analysis of the milks.For example, “at the seventh month of pregnancy in a heifer the secretions from the mammary gland contain about 9.1 per cent. of albumen and globulin and about 4 per cent. of casein-not very dis- similar to the proportion in cats’ milk-and very different from the 0.4 per cent. of albumen and globulin and 3 per cent. of casein of normal cows’ milk. Similar considerations apply to the casein - lactose ratios in some species, such as the mare and donkey, which have a higher lactose - protein ratio than the sheep, goat and cow.” On similar lines, Hammond deals with the composition of meat and eggs. It seems clear from these studies of genetic differences that the interpretation is dependent on a profound knowledge of the primary composition of the relevant living and evoluting animal.A final lighter touch in this positive affirmation must, I think, be referred to when, in dealing with the inherited quality of the relative quantities of the different albumen layers of the egg, it is noted that this has a com- mercial importance from the point of view of the poaching of eggs. THE TRUMAN FOURTH POINT AND AN IMPLEMENTATION So far the examples quoted are of analytical work done or being done; looking forward, perhaps one of the most important investigations now being awaited in agriculture is that dealing with a better knowledge of the soil. In January, 1949, President Truman put forward his now much discussed Fourth Point: a call for the intensification and sharing of American technological knowledge for the benefit of the undeveloped areas of the world.Later in 1949, the Parliamentary and Scientific Committee-an unofficial group of members of both Houses of Parliament and representatives of certain scientific societies and technical institutions-set up a sub-committee to consider the political and scientific implications, and the interim report of this sub-committee sets out the steps considered to be necessary for establishing or improving crops and crop produc- tion in these circumstances. Briefly stated these steps are- (1) Supplementation of ordinary ground geological survey by stereoscopic examination of air photographs.(2) Eradication of tsetse as preliminary to bush clearance. (3) Establishment of research centres in pasture development. (4) The fullest attention to water : supply, conservation, irrigation and drainage. (5) Survey of crops and determinative factors, such as soil conditions, plant pathology, pests and fertilisers. Clearly attention is here directed to such undeveloped areas as are now in existence in many parts of Central Africa, where regeneration and the establishment of fertile soil is a task of immense difficulty. When these five suggested steps are carefully considered it will be observed that they constitute a chronological sequence of work, from preliminary survey, through pest eradication, establishment of pasture research centres and attention to water, to examination of the soil and soil conditions.The endeavour to control or favourably influence conditions directly or indirectly affecting crop production, is quite properly of first importance, and is, of course, indispensable, but it is doubtful whether the enormous importance of a basic or fundamental knowledge of the soil is sufficiently appreciated. The ill-fated plan for the mechanised production of groundnuts in East and Central Africa was conceived as a solution of the end-of-the-war shortage of fats and animal feeding stuffs, and it may well be said, as it came into operation in 1948, that it anticipated the Truman Fourth Point. It may also be said that the major cause of the failure t o attain any com- mercial success was lack of sufficient knowledge of the soil.Contrary to much public opinion, a very considerable amount of investigational and research work on the soil and groundnut production had been undertaken. The First Annual Report of the Overseas Food Cor- porationlg includes a very full and complete account of the results of soil analysis and small plot experiments which had been undertaken. Samples of soil from the various districts were subjected to analysis on the conventional lines now customary in English agricultural institutions, covering the range of pH values and amounts of “available” P, Ca, Mg and K,274 ADDRESS OF THE RETIRING PRESIDENT [Vol. 76 and, as was expected, a deficiency of P was found to be general. An interesting relationship of N to P, for these soils, was determined. Furthermore, experimental work with different types of phosphatic materials and resultant yields of groundnuts showed that the deter- mination of citric-solubility of the phosphate in these materials was a useful criterion.So it may be fairly said that the major operation of ,growing groundnuts was not initiated without substantial preliminary work. But Africa has been gloomily described as a dying land,20 presumably in the same sense that Babylonia may now be said to be dead. Sand and wild vegetation cover buildings and monuments, olive groves and cornfields in the Mediterranean littoral where once Roman colonies flourished; the Sahara and other deserts extend their boundaries year by year, and new deserts are stated to be emerging; the forests are being felled or burnt down, to be followed by soil and wind erosions and the silting up of rivers; lands are being over-grazed with the same ultimate result; the water table falls and the land dries up.It seems reasonable, therefore, to assume that as the soil is the food-store for all the minerals essential for plant growth, then in countries such as East and Central Africa, where the soil may have suffered seriously over many years from leaching and oxidation by a tropical sun, the soil analysis necessary to ascertain mineral deficiencies, the chemical and physical characteristics of the clay and organic fractions, and indeed possibly the condition of the population of micro-organisms, must of necessity be much more complete, intricate and searching than that normally required in lands such as England, where it has been under cultivation for very many years.It may well be that the unexpected poor yield of groundnuts was due to some such cause as the deficiency of a trace element. Recently, Professor T. Wallace,21 dealing with research on the status and functions of mineral nutrients, has stressed the importance of the inter-relationship between the various elements, and regards the various factors affecting the supply of mineral nutrients in soils as- (1) The fixing power of soil. (2) Soil reaction. (3) Organic matter, drainage conditions and aeration. Even more emphatic was the profound thought of Professor N. M. Comber at the 1949 meeting of the British Association, when he said: “We have considerable knowledge of genetics and plant breeding, there is much work done in the problems of plant pathology, bacteriology, mycology and entomology, the long-standing science of botany has brought detailed know- ledge of the plant and the much more recent science of pedology is bringing new knowledge of the soil, knowledge of its formation, its morphology and the structure of its materials.But the basis of it all is the relationship of the soil and the plant and that is an almost un- explored field. . . . It used to be stated-indeed in some writings still is-that the root hairs dip into the soil solution and the root albsorbs substances dissolved there just as in the case of plants grown in culture solutions. Some of us were able to show some time ago that the problem is much more complex than that. The plant and the soil are not two separate things that just touch one another: the intermingling of their colloids makes them one system-the soil colloids on the roots cannot be removed without rupturing the roots, they have come to be a part of the plant, and what goes on in this soil -plant system is the fundamental thing in all farming.” Briefly, it is important to know not only how the plant is fed, but also with what it is fed. For this purpose the aid of chemical analysis in its most advanced form is fundamental to the knowledge of the composition of the nutrients translocated from the soil through the semi-permeable rootlets or hairs of the plant roots into the plants. 1. -2. 3. 4. 5. 6. 7. 8. 9. 10. 11. REFERENCES Eynon, L., Analyst, 1949, 74, 163. Cook, J. W., Chem. and Ind., April 29th, 1950, No. 17, 325. Wilson, C. L., “The Future of Analytical Chemistry,” Chemical Age, 1950, 62, 677. Zuckerman, S., J . Sci. and Agric., 1950, 1,. 255. Bledislow (Viscount), Chern. and Ind., Dec. 24th, 1949, No. 52, 899. The Times, Dec. 19th, 1950. Askew, H. O., and Dixon, J. H., The New Zealmad Journal of Science and Technology, 1949, 18, 73. Tosie, J., and Mitchell, R. L., Nature, 1948, 162, 602. Stapledon, Sir George, The Times, Dec. 21st, 1948. Agriculture, 1950, 56, 493. Hamilton, R. A., “Role of Fertilisers in Increasing Output from Grass-land,” The Fertiliser Society, Proceedings No. 8, 1950.May, 19511 ANNIVERSARY DINNER 275 Watson, S. J., “The Chemistry of Ensilage,” Chem. and Ind., Oct. 8th, 1949, No. 41, 699. Pearsall, W. H., and Fogg, G. E., “The Utilization of Algae for Industrial Photosynthesis,” Food Eaton, F. M., Soil Science, 1950, 69, 123. Haywood, E., Chem. and Ind., Dec. 23rd, 1950, No. 51, 825. Jacob, K. D., “Fertiliser Technology Research in the United States Department of Agriculture,” Hamence, J. H., J . Sci. Food and Agric., 1950, No. 3, 92. Hammond, J., “Genetic Differences in the Composition of Animal Products,” Chem. and Ind., “The First Annual Report and Statement of Accounts of the Overseas Food Corporation for the H.M. Stationery Office. Vogt, W., “Road to Survival,” Victor Gollancz Ltd., London, 1949. Wallace, T., “The Mineral Nutrition of Crops-Some Recent Developments in Research,”N.A.A.S. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Science Abstracts, 1951, 23, 1. The Fertiliser Society, Proceedings No. 9, 1950. Aug. 26th, 1950, No. 34, 631. period ended March 31st, 1949.” Quarterly Review, No. 11, 1951.